{"id":45273,"date":"2021-01-28T13:30:00","date_gmt":"2021-01-28T13:30:00","guid":{"rendered":"https:\/\/discover.restek.com\/uncategorized\/guide-to-gc-column-selection-and-optimizing-separations\/"},"modified":"2026-01-03T19:31:49","modified_gmt":"2026-01-03T19:31:49","slug":"guide-to-gc-column-selection-and-optimizing-separations","status":"publish","type":"post","link":"https:\/\/discover.restek.com\/it\/articles\/gnar1724\/guide-to-gc-column-selection-and-optimizing-separations","title":{"rendered":"Guide to GC Column Selection and Optimizing Separations"},"content":{"rendered":"\n<p><style>     ul li { margin-top: 5px; }     ol li { margin-top: 5px; }  <\/style><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Learn how to choose the right column the first time.<\/li>\n\n\n\n<li>Optimize separations for the best balance of resolution and speed.<\/li>\n\n\n\n<li>Troubleshoot quickly and effectively based on chromatographic symptoms.<\/li>\n<\/ul>\n\n\n\n<p>You can improve lab productivity by assuring that speed and resolution are optimized. One of the best ways to do this is to use the resolution equation (Figure 1) as the key to controlling your separations. This fundamental equation helps you choose the best column stationary phase, length, inner diameter (ID), and film thickness for your specific applications. Once you understand the basics of how resolution is related to column characteristics, optimizing your analysis for both separation and speed becomes easier. This GC column selection guide discusses the basics of separation and teaches you how to choose the right GC column!<\/p>\n\n\n\n<p>Resolution is the goal of every chromatographer, but how much resolution is enough? Practically speaking, we need enough retention to get sharp symmetrical peaks that are baseline resolved from each other, but not so much retention, that retention times are too long, and peaks start to broaden. To achieve this goal, we must consider the column and non-column factors that affect our \u201cperfect separation.\u201d Only then can we work towards selecting the right column and optimizing GC separations and analysis speed. Now, let\u2019s consider the separation factor (\u03b1), retention factor (k), and efficiency (N) in turn and how they can help you select the right column and optimize your separation.<\/p>\n\n\n<style>.kb-image45273_e27d6e-e6 .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<div class=\"wp-block-kadence-image kb-image45273_e27d6e-e6\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"485\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-01-1-1024x485.jpg\" alt=\"\" class=\"kb-img wp-image-63208\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-01-1-1024x485.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-01-1-300x142.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-01-1-768x364.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-01-1-1536x727.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-01-1.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/div>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><strong>Figure 1:<\/strong>\u00a0The resolution equation and factors that affect it.<\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n<style>.kb-image45273_f287de-a8 .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<figure class=\"wp-block-kadence-image kb-image45273_f287de-a8 size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"387\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-01-1024x387.jpg\" alt=\"\" class=\"kb-img wp-image-20512\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-01-1024x387.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-01-300x114.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-01-768x291.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-01-1536x581.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-01.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n<\/div><\/div><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Shortcut to Column Selection<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Look for application-specific stationary phases first; these columns are optimized for specific analyses and will provide the best resolution in the shortest time (Table III).<\/li>\n\n\n\n<li>If an application-specific column is not available, and you need to measure low concentrations or are using a mass spectrometer (MS), then choose an Rxi column. Rxi technology unites outstanding inertness, low bleed, and high reproducibility, resulting in high-performance GC columns that are ideal for trace analysis and MS work (Table II).<\/li>\n\n\n\n<li>For other methods, choose a general-purpose Rtx column (Table II).<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\">Use Separation Factor (\u03b1) to Choose the Best Stationary Phase<\/h2>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<style>.kb-image45273_4d6d84-ab .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<div class=\"wp-block-kadence-image kb-image45273_4d6d84-ab\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"69\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724B-01-1024x69.jpg\" alt=\"\" class=\"kb-img wp-image-18310\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724B-01-1024x69.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724B-01-300x20.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724B-01-768x52.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724B-01-1536x104.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724B-01.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/div>\n\n\n\n<p>Choosing the right stationary phase is the first step toward optimizing your GC separation. It is the most important decision you will make because the separation factor (\u03b1) has the greatest impact on resolution, and it is strongly affected by stationary phase polarity and selectivity.<\/p>\n\n\n\n<p>Stationary phase&nbsp;<em>polarity<\/em>&nbsp;is determined by the type and amount of functional groups in the stationary phase. When choosing a column, consider the polarity of both the stationary phase and your target analytes. If the stationary phase and analyte polarities are similar, then the attractive forces are strong, and more retention will result. Greater retention often results in increased resolution. Stationary phase polarity strongly influences column selectivity and the separation factor, making it a useful consideration when selecting a column.<\/p>\n\n\n\n<p>Stationary phase&nbsp;<em>selectivity<\/em>&nbsp;is defined by IUPAC as the extent to which other substances interfere with the determination of a given substance. Selectivity is directly related to stationary phase composition and how it interacts with target compounds through intermolecular forces (e.g., hydrogen bonding, dispersion, dipole-dipole interactions, and shape selectivity). As methyl groups in the stationary phase are replaced by different functionalities, such as phenyl or cyanopropyl pendant groups, compounds that are more soluble with those functional groups (e.g., aromatics or polar compounds, respectively) will inter- act more and be retained longer, often leading to better resolution and increased selectivity. In another example of the effect of stationary phase-analyte interactions, an Rtx-200 stationary phase is highly selective for analytes containing lone pair electrons, such as halogen, nitrogen, or carbonyl groups, due to interactions with the fluorine pendant group in this phase. Selectivity can be approximated using existing applications or retention indices (Table I), making these useful tools for comparing phases and deciding which is most appropriate for a specific analysis.<\/p>\n\n\n\n<p>Due to their influence on the separation factor, polarity and selectivity are primary considerations when selecting a column. However, temperature limits must also be considered. In general, highly polar stationary phases have lower maximum operating temperatures, so choosing a column with the appropriate maximum operating temperature, as well as optimal polarity and selectivity for the type of compounds being analyzed, is crucial. Use Table II and Figure 2 to determine which general-purpose column is most appropriate based on the selectivity, polarity, and the temperature requirements of your analysis. See Table III for a list of specialty stationary phases designed for specific applications.<\/p>\n\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Tech Tip<\/h3>\n\n\n\n<p>In many cases, different GC oven temperature programs can change the elution order of sample analytes on the same column. Reconfirm elution orders if changing GC oven temperature programs.<\/p>\n\n\n\n<p><strong>Table I:<\/strong> Kovat\u2019s retention indices for GC phases can be used to approximate selectivity.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Stationary Phase<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\"><strong>Benzene<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\"><strong>Butanol<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\"><strong>Pentanone<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\"><strong>Nitropropane<\/strong><\/td><\/tr><tr><td>100% Dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">651<\/td><td class=\"has-text-align-center\" data-align=\"center\">651<\/td><td class=\"has-text-align-center\" data-align=\"center\">667<\/td><td class=\"has-text-align-center\" data-align=\"center\">705<\/td><\/tr><tr><td>5% Diphenyl\/95% dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">667<\/td><td class=\"has-text-align-center\" data-align=\"center\">667<\/td><td class=\"has-text-align-center\" data-align=\"center\">689<\/td><td class=\"has-text-align-center\" data-align=\"center\">743<\/td><\/tr><tr><td>20% Diphenyl\/80% dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">711<\/td><td class=\"has-text-align-center\" data-align=\"center\">704<\/td><td class=\"has-text-align-center\" data-align=\"center\">740<\/td><td class=\"has-text-align-center\" data-align=\"center\">820<\/td><\/tr><tr><td>6% Cyanopropylphenyl\/94% dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">689<\/td><td class=\"has-text-align-center\" data-align=\"center\">729<\/td><td class=\"has-text-align-center\" data-align=\"center\">739<\/td><td class=\"has-text-align-center\" data-align=\"center\">816<\/td><\/tr><tr><td>35% Diphenyl\/65% dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">746<\/td><td class=\"has-text-align-center\" data-align=\"center\">733<\/td><td class=\"has-text-align-center\" data-align=\"center\">773<\/td><td class=\"has-text-align-center\" data-align=\"center\">867<\/td><\/tr><tr><td>Trifluoropropylmethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">738<\/td><td class=\"has-text-align-center\" data-align=\"center\">758<\/td><td class=\"has-text-align-center\" data-align=\"center\">884<\/td><td class=\"has-text-align-center\" data-align=\"center\">980<\/td><\/tr><tr><td>Phenyl methyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">778<\/td><td class=\"has-text-align-center\" data-align=\"center\">769<\/td><td class=\"has-text-align-center\" data-align=\"center\">813<\/td><td class=\"has-text-align-center\" data-align=\"center\">921<\/td><\/tr><tr><td>14% Cyanopropylphenyl\/86% dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">721<\/td><td class=\"has-text-align-center\" data-align=\"center\">778<\/td><td class=\"has-text-align-center\" data-align=\"center\">784<\/td><td class=\"has-text-align-center\" data-align=\"center\">881<\/td><\/tr><tr><td>65% Diphenyl\/35% dimethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">794<\/td><td class=\"has-text-align-center\" data-align=\"center\">779<\/td><td class=\"has-text-align-center\" data-align=\"center\">825<\/td><td class=\"has-text-align-center\" data-align=\"center\">938<\/td><\/tr><tr><td>50% Cyanopropylmethyl\/50% phenylmethyl polysiloxane<\/td><td class=\"has-text-align-center\" data-align=\"center\">847<\/td><td class=\"has-text-align-center\" data-align=\"center\">937<\/td><td class=\"has-text-align-center\" data-align=\"center\">958<\/td><td class=\"has-text-align-center\" data-align=\"center\">958<\/td><\/tr><tr><td>Polyethylene glycol<\/td><td class=\"has-text-align-center\" data-align=\"center\">963<\/td><td class=\"has-text-align-center\" data-align=\"center\">1158<\/td><td class=\"has-text-align-center\" data-align=\"center\">998<\/td><td class=\"has-text-align-center\" data-align=\"center\">1230<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><strong>Figure 2:<\/strong>\u00a0Polarity scale of common stationary phases.<\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:10%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"500\" height=\"500\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a.jpg\" alt=\"\" class=\"wp-image-20391\" style=\"object-fit:cover\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a.jpg 500w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a-300x300.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a-150x150.jpg 150w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column has-large-font-size is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:90%\">\n<p class=\"has-large-font-size\">STATIONARY PHASE<\/p>\n<\/div>\n<\/div>\n\n\n<style>.kb-image45273_a94049-12 .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<div class=\"wp-block-kadence-image kb-image45273_a94049-12\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"608\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-02b-1024x608.jpg\" alt=\"\" class=\"kb-img wp-image-20518\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-02b-1024x608.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-02b-300x178.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-02b-768x456.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-02b-1536x911.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724B-02b.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/div>\n\n<\/div><\/div><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Tech Tip<\/h3>\n\n\n\n<p>Any homologous series of compounds, that is, analytes from the same chemical class (e.g., all alcohols, all ketones, or all aldehydes, etc.) will elute in boiling point order on any stationary phase. However, when different compound classes are mixed together in one sample, intermolecular forces between the analytes and the stationary phase are the dominant separation mechanism, not boiling point.<\/p>\n\n\n\n<p><strong>Table II:<\/strong>&nbsp;Relative polarity and maximum temperature are important considerations when selecting a GC stationary phase.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Restek<\/strong><\/td><td><strong>Phase Composition (USP Nomenclature)<\/strong><\/td><td><strong>Restek\u2019s Max Temps*<\/strong><\/td><td class=\"has-text-align-left\" data-align=\"left\"><strong>Agilent<\/strong><\/td><td><strong>Phenomenex<\/strong><\/td><\/tr><tr><td>Rxi-1HT, <br>Rxi-1ms, Rtx-1<\/td><td>100% Dimethyl polysiloxane (G1, G2, G38)<\/td><td>400 \u00b0C<br>350 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">HP-1\/HP-1ms, <br>DB-1\/DB-1ms, VF-1ms, CP Sil 5 CB, Ultra 1, DB-1ht, HP-1ms UI, DB-1ms UI<\/td><td>ZB-1, ZB-1MS, <br>ZB-1HT Inferno<\/td><\/tr><tr><td>Rxi-5HT, <br>Rtx-5ms, <br>Rxi-5ms, Rtx-5<\/td><td>5% Diphenyl\/95% dimethyl polysiloxane (G27, G36)<\/td><td>400 \u00b0C<br>350 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">HP-5\/HP-5ms, DB-5, Ultra 2, DB-5ht, <br>VF-5ht, CP-Sil 8 CB<\/td><td>ZB-5, ZB-5HT Inferno, ZB-5ms<\/td><\/tr><tr><td>Rxi-5Sil MS<\/td><td>5% (1,4-bis(dimethylsiloxy) phenylene\/95% dimethyl polysiloxane<\/td><td>350 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-5ms UI, <br>DB-5ms,VF-5ms<\/td><td>ZB-5msi<\/td><\/tr><tr><td>Rxi-XLB<\/td><td>Proprietary Phase<\/td><td>360 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-XLB, VF-Xms<\/td><td>MR1, ZB-XLB<\/td><\/tr><tr><td>Rtx-20<\/td><td>20% Diphenyl\/80% dimethyl polysiloxane (G28, G32)<\/td><td>320 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-35<\/td><td>35% Diphenyl\/65% dimethyl polysiloxane (G42)<\/td><td>320 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">HP-35, DB-35<\/td><td>ZB-35<\/td><\/tr><tr><td>Rxi-35Sil MS<\/td><td>Proprietary Phase<\/td><td>360 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-35ms, DB-35ms UI, VF-35ms<\/td><td>MR2<\/td><\/tr><tr><td>Rtx-50<\/td><td>Phenyl methyl polysiloxane (G3)<\/td><td>320 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rxi-17<\/td><td>50% Diphenyl\/50% dimethyl polysiloxane<\/td><td>320 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-17ms, VF-17ms, <br>CP Sil 24 CB<\/td><td>ZB-50<\/td><\/tr><tr><td>Rxi-17Sil MS<\/td><td>Proprietary Phase<\/td><td>360 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-17ms, VF-17ms, <br>CP Sil 24 CB<\/td><td>ZB-50<\/td><\/tr><tr><td>Rtx-65<\/td><td>65% Diphenyl\/35% dimethyl polysiloxane (G17)<\/td><td>300 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rxi-624Sil MS<\/td><td>Proprietary Phase<\/td><td>320 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-624 UI, VF-624ms, CP-Select 624 CB<\/td><td>ZB-624<\/td><\/tr><tr><td>Rtx-1301, <br>Rtx-624<\/td><td>6% Cyanopropylphenyl\/94% dimethyl polysiloxane (G43)<\/td><td>280 \u00b0C<br>240 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-1301, DB-624, <br>CP-1301, VF-1301ms, VF-624ms<\/td><td>ZB-624<\/td><\/tr><tr><td>Rtx-1701<\/td><td>14% Cyanopropylphenyl\/86% dimethyl polysiloxane (G46)<\/td><td>280 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-1701, VF-1701ms, CP Sil 19 CB, <br>VF-1701 Pesticides, DB-1701R<\/td><td>ZB-1701, ZB-1701P<\/td><\/tr><tr><td>Rtx-200<\/td><td>Trifluoropropyl methyl polysiloxane (G6)<\/td><td>360 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-200, VF-200ms, DB-210<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-200ms<\/td><td>Trifluoropropyl methyl polysiloxane (G6)<\/td><td>340 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-200, VF-200ms, DB-210<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-225<\/td><td>50% Cyanopropyl methyl\/50% phenylmethyl polysiloxane (G7, G19)<\/td><td>240 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">DB-225ms, <br>CP Sil 43 CB<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-440<\/td><td>Proprietary Phase<\/td><td>340 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\" colspan=\"2\"><strong>RESTEK INNOVATION<\/strong><\/td><\/tr><tr><td>Rtx-2330<\/td><td>90% Biscyanopropyl\/10% cyanopropylphenyl polysiloxane (G48)<\/td><td>275 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">VF-23ms<\/td><td>\u2014<\/td><\/tr><tr><td>Rt-2560<\/td><td>Biscyanopropyl polysiloxane<\/td><td>250 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">HP-88, CP Sil 88<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-Wax<\/td><td>Polyethylene glycol (G14, G15, G16, G20, G39)<\/td><td>250 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">CP-Wax 52 CB, <br>DB-Wax, DB-WAX UI<\/td><td>ZB-WAX<\/td><\/tr><tr><td>Stabilwax<\/td><td>Polyethylene glycol (G14, G15, G16, G20, G39)<\/td><td>260 \u00b0C<\/td><td class=\"has-text-align-left\" data-align=\"left\">HP-INNOWax, <br>VF-WaxMS<\/td><td>ZB-WAXPlus<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>* Maximum operating temperatures may vary with column film thickness.<\/p>\n\n\n\n<p><strong>Table III:&nbsp;&nbsp;<\/strong>Application-specific phases designed for particular analyses.<\/p>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td><strong>Restek<\/strong><\/td>\n<td><strong>Applications<\/strong><\/td>\n<td><strong>Agilent<\/strong><\/td>\n<td><strong>Supelco<\/strong><\/td>\n<td><strong>Macherey-Nagel<\/strong><\/td>\n<td><strong>SGE<\/strong><\/td>\n<td><strong>Phenomenex<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-Volatile Amine<\/td>\n<td>Volatile amines<\/td>\n<td>CP-VolAmine<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-5Amine<\/td>\n<td>Amines<\/td>\n<td>CP-Sil 8 CB<\/td>\n<td>\u2014<\/td>\n<td>OPTIMA 5 Amine<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-35Amine<\/td>\n<td>Amines<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Stabilwax-DB<\/td>\n<td>Amines<\/td>\n<td>CAM, CP WAX 51<\/td>\n<td>Carbowax Amine<\/td>\n<td>FS-CW 20 M-AM<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Stabilwax-DA<\/td>\n<td>Free fatty acids<\/td>\n<td>HP-FFAP,<br \/>DB-FFAP,<br \/>VF-DA,<br \/>CP WAX58 CB,<br \/>CP-FFAP CB<\/td>\n<td>Nukol<\/td>\n<td>PERMABOND FFAP,<br \/>OPTIMA FFAP,<br \/>OPTIMA FFAP Plus<\/td>\n<td>BP-21<\/td>\n<td>ZB-FFAP<\/td>\n<\/tr>\n<tr>\n<td colspan=\"7\"><strong>Chiral Columns<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rt-\u03b2DEXm,<br \/>Rt-\u03b2DEXsm,<br \/>Rt-\u03b2DEXse,<br \/>Rt-\u03b2DEXsp,<br \/>Rt-\u03b2DEXsa,<br \/>Rt-\u03b2DEXcst,<br \/>Rt-\u03b3DEXsa<\/td>\n<td>Chiral compounds<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td colspan=\"7\"><strong>Foods, Flavors, &amp; Fragrances<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rt-2560<\/td>\n<td><em>cis\/trans<\/em>\u00a0FAMEs<\/td>\n<td>HP-88<\/td>\n<td>SPB-2560<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>FAMEWAX<\/td>\n<td>Marine oils<\/td>\n<td>DB-FATWAX UI<\/td>\n<td>Omegawax<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-65TG<\/td>\n<td>Triglycerides<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rxi-PAH<\/td>\n<td>Polycyclic aromatic hydrocarbons (PAHs)<\/td>\n<td>Agilent Select PAH<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td colspan=\"7\"><strong>Petroleum &amp; Petrochemical<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rxi-LAO<\/td>\n<td>Linear alpha olefin impurities<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rt-Alumina BOND\/CFC<\/td>\n<td>Chlorinated fluorocarbons (CFCs)<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rt-Alumina BOND\/MAPD<\/td>\n<td>Trace analysis of methyl acetylene, propadiene, and acetylene<\/td>\n<td>Select Al\u20820\u2083 MAPD<\/td>\n<td>\u00a0<\/td>\n<td>\u00a0<\/td>\n<td>\u00a0<\/td>\n<td>\u00a0<\/td>\n<\/tr>\n<tr>\n<td>Rtx-DHA<\/td>\n<td>Detailed hydrocarbon analysis<\/td>\n<td>HP-PONA, DB-Petro, CP Sil PONA CB<\/td>\n<td>Petrocol DH<\/td>\n<td>\u2014<\/td>\n<td>BP1PONA<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-2887,<br \/>MXT-2887<\/td>\n<td>Hydrocarbons (ASTM D2887)<\/td>\n<td>DB-2887<\/td>\n<td>Petrocol 2887,<br \/>Petrocol EX2887<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>D3606<\/td>\n<td>Ethanol (ASTM D3606)<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rt-TCEP<\/td>\n<td>Aromatics and oxygenates in gasoline<\/td>\n<td>CP-TCEP<\/td>\n<td>TCEP<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>MXT-1HT SimDist<\/td>\n<td>Simulated distillation<\/td>\n<td>DB-HT-SimDis,<br \/>CP-SimDist,<br \/>CP-SimDist Ultimetal<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>BPX1<\/td>\n<td>ZB-1XT SimDist<\/td>\n<\/tr>\n<tr>\n<td>Rtx-Biodiesel TG,<br \/>MXT-Biodiesel TG<\/td>\n<td>Triglycerides in biodiesel<\/td>\n<td>Biodiesel,<br \/>Select Biodiesel<\/td>\n<td>\u2014<\/td>\n<td>OPTIMA Biodiesel<\/td>\n<td>\u2014<\/td>\n<td>ZB-Bioethanol<\/td>\n<\/tr>\n<tr>\n<td colspan=\"7\"><strong>Clinical\/Forensic<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-BAC Plus 1<\/td>\n<td>Blood alcohol testing<\/td>\n<td>DB-ALC1<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>ZB-BAC1<\/td>\n<\/tr>\n<tr>\n<td>Rtx-BAC Plus 2<\/td>\n<td>Blood alcohol testing<\/td>\n<td>DB-ALC2<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>ZB-BAC2<\/td>\n<\/tr>\n<tr>\n<td colspan=\"7\"><strong>Pharmaceutical<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rxi-624Sil MS (G43)<\/td>\n<td>Organic volatile impurities (USP &lt;467&gt;)<\/td>\n<td>DB-624,<br \/>VF-624ms,<br \/>CP-Select 624 CB<\/td>\n<td>\u2014<\/td>\n<td>OPTIMA 624 LB<\/td>\n<td>BP624<\/td>\n<td>ZB-624<\/td>\n<\/tr>\n<tr>\n<td>Rtx-5 (G27)<\/td>\n<td>Organic volatile impurities (USP &lt;467&gt;)<\/td>\n<td>HP-5, DB-5,<br \/>CP Sil 8 CB<\/td>\n<td>SPB-5<\/td>\n<td>OPTIMA 5<\/td>\n<td>BP5<\/td>\n<td>ZB-5<\/td>\n<\/tr>\n<tr>\n<td>Stabilwax (G16)<\/td>\n<td>Organic volatile impurities (USP &lt;467&gt;)<\/td>\n<td>HP-INNOWax,<br \/>CP Wax 52 CB,<br \/>VF-WAX MS<\/td>\n<td>Supelcowax-10<\/td>\n<td>OPTIMA WAXplus<\/td>\n<td>\u2014<\/td>\n<td>ZB-WAXplus<\/td>\n<\/tr>\n<tr>\n<td colspan=\"7\"><strong>Environmental<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rxi-SVOCms<\/td>\n<td>Semivolatiles, PAHs<\/td>\n<td>DB-UI 8270D<\/td>\n<td>\u00a0<\/td>\n<td>\u00a0<\/td>\n<td>\u00a0<\/td>\n<td>ZB-SemiVolatiles<\/td>\n<\/tr>\n<tr>\n<td>Rxi-5Sil MS<\/td>\n<td>Semivolatiles, PAHs<\/td>\n<td>DB-5ms,<br \/>DB-5msUI,<br \/>VF-5ms,<br \/>CP-Sil 8 CB<\/td>\n<td>SLB-5ms<\/td>\n<td>OPTIMA 5MS Accent<\/td>\n<td>BPX5<\/td>\n<td>ZB-5msi<\/td>\n<\/tr>\n<tr>\n<td>Rtx-VMS<\/td>\n<td>Volatiles (EPA Methods 8260, 624, 524)<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rxi-624Sil MS<\/td>\n<td>Volatiles (EPA Methods 624)<\/td>\n<td>DB-624,<br \/>VF-624ms,<br \/>CP-Select 624 CB<\/td>\n<td>\u2014<\/td>\n<td>OPTIMA 624 LB<\/td>\n<td>BP624<\/td>\n<td>ZB-624<\/td>\n<\/tr>\n<tr>\n<td>Rtx-502.2<\/td>\n<td>Volatiles (EPA Methods 8010, 8020, 502.2, 601, 602)<\/td>\n<td>DB-502.2<\/td>\n<td>VOCOL<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-Volatiles<\/td>\n<td>Volatiles (EPA Methods 8010, 8020, 502.2, 601, 602)<\/td>\n<td>\u2014<\/td>\n<td>VOCOL<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-VRX<\/td>\n<td>Volatiles (EPA Methods 8010, 8020, 502.2, 601, 602)<\/td>\n<td>DB-VRX<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Rtx-CLPesticides<\/td>\n<td>Organochlorine pesticides<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-CLPesticides2<\/td>\n<td>Organochlorine pesticides<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-1614<\/td>\n<td>Brominated flame retardants<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-PCB<\/td>\n<td>Polychlorinated biphenyl (PCB) congeners<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rxi-XLB<\/td>\n<td>Polychlorinated biphenyl (PCB) congeners<\/td>\n<td>DB-XLB,VF-XMS<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>MR1, ZB-XLB<\/td>\n<\/tr>\n<tr>\n<td>Rtx-OPPesticides<\/td>\n<td>Organophosphorus pesticides<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-OPPesticides2<\/td>\n<td>Organophosphorus pesticides<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-Dioxin2<\/td>\n<td>Dioxins and furans<\/td>\n<td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rtx-Mineral Oil<\/td>\n<td>DIN EN ISO 9377-2<\/td>\n<td>Select Mineral Oil<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<p style=\"padding-top:0;padding-bottom:0\">* Maximum operating temperatures may vary with column film thickness.<\/p>\n\n\n\n<p><strong>Table III:&nbsp;&nbsp;<\/strong>Application-specific phases designed for particular analyses.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Restek<\/strong><\/td><td><strong>Applications<\/strong><\/td><td><strong>Agilent<\/strong><\/td><td><strong>Supelco<\/strong><\/td><td><strong>Macherey-Nagel<\/strong><\/td><td><strong>SGE<\/strong><\/td><td><strong>Phenomenex<\/strong><\/td><\/tr><tr><td>Rtx-Volatile Amine<\/td><td>Volatile amines<\/td><td>CP-VolAmine<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-5Amine<\/td><td>Amines<\/td><td>CP-Sil 8 CB<\/td><td>\u2014<\/td><td>OPTIMA 5 Amine<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-35Amine<\/td><td>Amines<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Stabilwax-DB<\/td><td>Amines<\/td><td>CAM, CP WAX 51<\/td><td>Carbowax Amine<\/td><td>FS-CW 20 M-AM<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Stabilwax-DA<\/td><td>Free fatty acids<\/td><td>HP-FFAP,<br>DB-FFAP,<br>VF-DA,<br>CP WAX58 CB,<br>CP-FFAP CB<\/td><td>Nukol<\/td><td>PERMABOND FFAP,<br>OPTIMA FFAP,<br>OPTIMA FFAP Plus<\/td><td>BP-21<\/td><td>ZB-FFAP<\/td><\/tr><tr><td colspan=\"7\"><strong>Chiral Columns<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rt-\u03b2DEXm,<br>Rt-\u03b2DEXsm,<br>Rt-\u03b2DEXse,<br>Rt-\u03b2DEXsp,<br>Rt-\u03b2DEXsa,<br>Rt-\u03b2DEXcst,<br>Rt-\u03b3DEXsa<\/td><td>Chiral compounds<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td colspan=\"7\"><strong>Foods, Flavors, &amp; Fragrances<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rt-2560<\/td><td><em>cis\/trans<\/em>&nbsp;FAMEs<\/td><td>HP-88<\/td><td>SPB-2560<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>FAMEWAX<\/td><td>Marine oils<\/td><td>DB-FATWAX UI<\/td><td>Omegawax<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-65TG<\/td><td>Triglycerides<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rxi-PAH<\/td><td>Polycyclic aromatic hydrocarbons (PAHs)<\/td><td>Agilent Select PAH<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td colspan=\"7\"><strong>Petroleum &amp; Petrochemical<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rxi-LAO<\/td><td>Linear alpha olefin impurities<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rt-Alumina BOND\/CFC<\/td><td>Chlorinated fluorocarbons (CFCs)<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rt-Alumina BOND\/MAPD<\/td><td>Trace analysis of methyl acetylene, propadiene, and acetylene<\/td><td>Select Al\u20820\u2083 MAPD<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><tr><td>Rtx-DHA<\/td><td>Detailed hydrocarbon analysis<\/td><td>HP-PONA, DB-Petro, CP Sil PONA CB<\/td><td>Petrocol DH<\/td><td>\u2014<\/td><td>BP1PONA<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-2887,<br>MXT-2887<\/td><td>Hydrocarbons (ASTM D2887)<\/td><td>DB-2887<\/td><td>Petrocol 2887,<br>Petrocol EX2887<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>D3606<\/td><td>Ethanol (ASTM D3606)<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rt-TCEP<\/td><td>Aromatics and oxygenates in gasoline<\/td><td>CP-TCEP<\/td><td>TCEP<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>MXT-1HT SimDist<\/td><td>Simulated distillation<\/td><td>DB-HT-SimDis,<br>CP-SimDist,<br>CP-SimDist Ultimetal<\/td><td>\u2014<\/td><td>\u2014<\/td><td>BPX1<\/td><td>ZB-1XT SimDist<\/td><\/tr><tr><td>Rtx-Biodiesel TG,<br>MXT-Biodiesel TG<\/td><td>Triglycerides in biodiesel<\/td><td>Biodiesel,<br>Select Biodiesel<\/td><td>\u2014<\/td><td>OPTIMA Biodiesel<\/td><td>\u2014<\/td><td>ZB-Bioethanol<\/td><\/tr><tr><td colspan=\"7\"><strong>Clinical\/Forensic<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-BAC Plus 1<\/td><td>Blood alcohol testing<\/td><td>DB-ALC1<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>ZB-BAC1<\/td><\/tr><tr><td>Rtx-BAC Plus 2<\/td><td>Blood alcohol testing<\/td><td>DB-ALC2<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>ZB-BAC2<\/td><\/tr><tr><td colspan=\"7\"><strong>Pharmaceutical<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rxi-624Sil MS (G43)<\/td><td>Organic volatile impurities (USP &lt;467&gt;)<\/td><td>DB-624,<br>VF-624ms,<br>CP-Select 624 CB<\/td><td>\u2014<\/td><td>OPTIMA 624 LB<\/td><td>BP624<\/td><td>ZB-624<\/td><\/tr><tr><td>Rtx-5 (G27)<\/td><td>Organic volatile impurities (USP &lt;467&gt;)<\/td><td>HP-5, DB-5,<br>CP Sil 8 CB<\/td><td>SPB-5<\/td><td>OPTIMA 5<\/td><td>BP5<\/td><td>ZB-5<\/td><\/tr><tr><td>Stabilwax (G16)<\/td><td>Organic volatile impurities (USP &lt;467&gt;)<\/td><td>HP-INNOWax,<br>CP Wax 52 CB,<br>VF-WAX MS<\/td><td>Supelcowax-10<\/td><td>OPTIMA WAXplus<\/td><td>\u2014<\/td><td>ZB-WAXplus<\/td><\/tr><tr><td colspan=\"7\"><strong>Environmental<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rxi-SVOCms<\/td><td>Semivolatiles, PAHs<\/td><td>DB-UI 8270D<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><td>ZB-SemiVolatiles<\/td><\/tr><tr><td>Rxi-5Sil MS<\/td><td>Semivolatiles, PAHs<\/td><td>DB-5ms,<br>DB-5msUI,<br>VF-5ms,<br>CP-Sil 8 CB<\/td><td>SLB-5ms<\/td><td>OPTIMA 5MS Accent<\/td><td>BPX5<\/td><td>ZB-5msi<\/td><\/tr><tr><td>Rtx-VMS<\/td><td>Volatiles (EPA Methods 8260, 624, 524)<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rxi-624Sil MS<\/td><td>Volatiles (EPA Methods 624)<\/td><td>DB-624,<br>VF-624ms,<br>CP-Select 624 CB<\/td><td>\u2014<\/td><td>OPTIMA 624 LB<\/td><td>BP624<\/td><td>ZB-624<\/td><\/tr><tr><td>Rtx-502.2<\/td><td>Volatiles (EPA Methods 8010, 8020, 502.2, 601, 602)<\/td><td>DB-502.2<\/td><td>VOCOL<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-Volatiles<\/td><td>Volatiles (EPA Methods 8010, 8020, 502.2, 601, 602)<\/td><td>\u2014<\/td><td>VOCOL<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-VRX<\/td><td>Volatiles (EPA Methods 8010, 8020, 502.2, 601, 602)<\/td><td>DB-VRX<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><tr><td>Rtx-CLPesticides<\/td><td>Organochlorine pesticides<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-CLPesticides2<\/td><td>Organochlorine pesticides<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-1614<\/td><td>Brominated flame retardants<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-PCB<\/td><td>Polychlorinated biphenyl (PCB) congeners<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rxi-XLB<\/td><td>Polychlorinated biphenyl (PCB) congeners<\/td><td>DB-XLB,VF-XMS<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>MR1, ZB-XLB<\/td><\/tr><tr><td>Rtx-OPPesticides<\/td><td>Organophosphorus pesticides<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-OPPesticides2<\/td><td>Organophosphorus pesticides<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-Dioxin2<\/td><td>Dioxins and furans<\/td><td colspan=\"5\"><strong>RESTEK INNOVATION<\/strong><strong><\/strong><\/td><\/tr><tr><td>Rtx-Mineral Oil<\/td><td>DIN EN ISO 9377-2<\/td><td>Select Mineral Oil<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><td>\u2014<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Select Column Film Thickness and Column ID Based on Retention Factor<\/h2>\n\n\n<style>.kb-image45273_6c30d5-4b .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<div class=\"wp-block-kadence-image kb-image45273_6c30d5-4b\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"69\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-02-1024x69.jpg\" alt=\"\" class=\"kb-img wp-image-18334\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-02-1024x69.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-02-300x20.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-02-768x52.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-02-1536x104.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-02.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/div>\n\n\n\n<p>Once you have chosen the stationary phase, you need to determine which column film thickness and inner diameter combination will give the retention factor (k) needed for optimal resolution and speed. Retention factor is sometimes referred to as \u201ccapacity factor,\u201d which should not be confused with sample loading capacity.<\/p>\n\n\n\n<p>The retention factor (k) of a column is based on the time an analyte spends in the stationary phase rela- tive to the time it spends in the carrier gas. As a general rule, the thicker the film and the smaller the inner diameter, the more an analyte will be retained. Note that as temperature increases k decreases, so at higher temperatures analytes stay in the carrier gas longer and are less retained.<\/p>\n\n\n\n<p>In practice, if the value of k is too large, the peak will broaden, which can reduce resolution by causing peaks to overlap or coelute. Narrow, symmetrical peaks are important to maximizing resolution, so the goal is to select a column with a sufficient retention factor, such that resolution occurs, and peak shape does not suffer. Once the proper stationary phase is selected, column film thickness, column inner diam- eter, and elution temperature should be optimized to produce an acceptable retention factor.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Tech Tip<\/h3>\n\n\n\n<p>The sample loading capacity of the column must also be considered; if the mass of the target analyte exceeds the sample loading capacity of the column, loss of resolution, poor reproducibility, and fronting peaks will result. A larger ID column with thicker film is recommended for higher concentration samples, such as purity analysis, to minimize sample overload.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Film Thickness<\/h3>\n\n\n\n<p>Film thickness (\u03bcm) has a direct effect on both the retention of each sample component and the maximum operating temperature of the column. When analyzing extremely volatile compounds, a thick film column should be used to increase retention; more separation is achieved because the compounds spend more time in the stationary phase. If analyzing high molecular weight compounds, a thinner film column should be used as this reduces the length of time that the analytes stay in the column and minimizes phase bleed at higher elution temperatures. Use Figure 3 to select the best film thickness for your application. Note that as a general rule, the thicker the film, the lower the maximum temperature; exceeding the maximum temperature can result in column bleed and should be avoided.<\/p>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><strong>Figure 3:<\/strong>\u00a0Characteristics and recommended applications based on film thickness.<\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:10%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"500\" height=\"500\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a.jpg\" alt=\"\" class=\"wp-image-20391\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a.jpg 500w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a-300x300.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-02a-150x150.jpg 150w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column has-large-font-size is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:90%\">\n<p class=\"has-large-font-size\">FILM THICKNESS<\/p>\n<\/div>\n<\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"528\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-03b-1024x528.jpg\" alt=\"\" class=\"wp-image-20404\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-03b-1024x528.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-03b-300x155.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-03b-768x396.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-03b-1536x792.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-03b.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n<\/div><\/div><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Tech Tip<\/h3>\n\n\n\n<p>Remember, when changing either film thickness and\/or the temperature program, you must reconfirm peak identifications as elution order changes can occur.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Inner Diameter (ID)<\/h3>\n\n\n\n<p>Column ID does not have as great an effect on retention factor as film thickness does. However, when selecting column ID with retention factor (k) in mind, a general rule of thumb applies; smaller ID columns produce higher retention factors compared to larger ID columns. This is due to less available mobile phase (carrier gas) volume in the column. Because smaller ID columns produce higher k values, they are more suited towards complex sample analysis where a range of low to high molecular weight compounds may exist in the sample (Figure 4). Keep in mind that both ID and film thickness should be optimized together to produce the best resolution and peak shape.<\/p>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><strong>Figure 4:<\/strong>\u00a0Characteristics and recommended applications based on column inner diameter.<\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:10%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"500\" height=\"500\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04a.jpg\" alt=\"\" class=\"wp-image-20415\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04a.jpg 500w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04a-300x300.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04a-150x150.jpg 150w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column has-large-font-size is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:90%\">\n<p class=\"has-large-font-size\">INNER DIAMETER<\/p>\n<\/div>\n<\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"479\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04b-1024x479.jpg\" alt=\"\" class=\"wp-image-20416\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04b-1024x479.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04b-300x140.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04b-768x359.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04b-1536x719.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-04b.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n<\/div><\/div><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Tech Tip<\/h3>\n\n\n\n<p>When choosing column ID, the injection technique is also important because the column ID may need to be selected based on whether a split, splitless, direct, cool on-column injection, or other sample transfer method is being used. For example, 0.53 mm ID columns are ideal for cool on-column injections since the syringe needle (26 gauge) will fit into the large column ID. In addition, the detector and its optimal flow rate must be considered. Some MS detectors can only operate under column flow rates of up to 1.5 mL\/min; therefore, a 0.53 mm ID column, which requires higher flows for proper chromatography, is not an option for MS work.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Phase Ratio (\u03b2)<\/h3>\n\n\n\n<p>The relationship between column inner diameter and stationary phase film thickness is expressed as phase ratio (\u03b2). If a good separation has been achieved on a larger diameter column, and a faster anal- ysis is desired, this can often be accomplished by reducing the inner diameter of the column without sacrificing, and sometimes even improving, separation efficiency. To maintain a similar compound elution pattern when narrowing column inner diameter, film thickness must also be changed. By choosing a column with a similar phase ratio, it will be easier to translate your application to the new column. Phase ratios for common column dimensions are given in Table IV. As shown here, an analyst wanting to decrease analysis time could switch from a 0.32 mm x 0.50 \u00b5m column (\u03b2 = 160) to a 0.25 mm x 0.25 \u03bcm column (\u03b2 = 250) and obtain a very similar separation upon proper method translation. Importantly, column inner diameter and stationary phase film thickness show a combined effect when it comes to sample loading capacity, which is decreased as column inner diameter and film thickness are reduced. It may be necessary to inject a lower sample amount in this case.<\/p>\n\n\n\n<p><strong>Table IV:&nbsp;<\/strong>Phase ratio (\u03b2)* values for common column dimensions. To maintain similar separations, choose columns with similar phase ratios when changing to a column with a different inner diameter or film thickness.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td class=\"has-text-align-left\" data-align=\"left\" rowspan=\"2\"><strong>Column ID<\/strong><\/td><td colspan=\"7\"><strong>Film Thickness (d<sub>f<\/sub>)<\/strong><\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\"><strong>0.10 \u00b5m<\/strong><\/td><td><strong>0.25 \u00b5m<\/strong><\/td><td><strong>0.50 \u00b5m<\/strong><\/td><td><strong>1.0 \u00b5m<\/strong><\/td><td><strong>1.5 \u00b5m<\/strong><\/td><td><strong>3.0 \u00b5m<\/strong><\/td><td><strong>5.0 \u00b5m<\/strong><\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">0.18 mm<\/td><td>450<\/td><td>180<\/td><td>90<\/td><td>45<\/td><td>30<\/td><td>15<\/td><td>9<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">0.25 mm<\/td><td>625<\/td><td><strong>250<\/strong><\/td><td>125<\/td><td>63<\/td><td>42<\/td><td>21<\/td><td>13<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">0.32 mm<\/td><td>800<\/td><td>320<\/td><td><strong>160<\/strong><\/td><td>80<\/td><td>53<\/td><td>27<\/td><td>16<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">0.53 mm<\/td><td>1325<\/td><td>530<\/td><td>265<\/td><td>128<\/td><td>88<\/td><td>43<\/td><td>27<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>*Phase ratio (\u03b2) = radius\/2df (Note: Convert variables to the same units prior to calculation.)<\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Consider Efficiency when Choosing Column Length, Column ID, and Carrier Gas<\/h2>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<style>.kb-image45273_1a2f1f-85 .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<figure class=\"wp-block-kadence-image kb-image45273_1a2f1f-85 size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"69\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-03-1024x69.jpg\" alt=\"\" class=\"kb-img wp-image-18340\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-03-1024x69.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-03-300x20.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-03-768x52.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-03-1536x104.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/equation-article-GNAR1724C-03.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Column Length<\/h3>\n\n\n\n<p>Capillary GC columns are made in various lengths, typically 10, 15, 30, 60, and 105 meters, depending on the inner diameter. Longer columns provide more resolving power than shorter columns of the same inner diameter, but they also increase analysis time and should be used only for applications demanding the utmost in separation power. Column length should only be considered once the stationary phase has been determined. This is because the separation factor has the greatest effect on resolution and it is maximized through proper stationary phase choice for the compounds of interest. Doubling the column length (e.g., 30 m to 60 m) increases resolution by approximately 40%, while analysis time can be twice as long. In addition, longer columns cost more. Conversely, if a separation can be performed on a shorter column (e.g., 15 m versus 30 m), then both analysis time and column cost will be less. Figure 5 summarizes the characteristics and general application parameters for a range of typical column lengths.<\/p>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><strong>Figure 5:<\/strong>\u00a0Characteristics and recommended applications based on column length.<\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:10%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"500\" height=\"500\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05a.jpg\" alt=\"\" class=\"wp-image-20427\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05a.jpg 500w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05a-300x300.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05a-150x150.jpg 150w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column has-large-font-size is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:90%\">\n<p class=\"has-large-font-size\">LENGTH<\/p>\n<\/div>\n<\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"501\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05b-1024x501.jpg\" alt=\"\" class=\"wp-image-20428\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05b-1024x501.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05b-300x147.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05b-768x376.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05b-1536x752.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-05b.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n<\/div><\/div><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Inner Diameter (ID)<\/h3>\n\n\n\n<p>Compared to larger ID columns, smaller ID columns generate more plates per meter and sharper peaks, leading to better separation efficiencies. When more complex samples need to be analyzed, smaller ID columns can produce better separation of closely eluting peaks than larger ID columns. However, sample loading capacities are lower for smaller ID columns. Smaller ID columns, especially those at 0.18 mm and less, demand highly efficient injection techniques so that the column efficiency is not lost at the point of sample introduction. Column characteristics based on ID are presented in Table V.<\/p>\n\n\n\n<p>Generally speaking, a 0.25 mm column will produce the most efficient sample analysis while simultaneously considering analysis time and sample loading capacity. For these reasons, in combination with its relatively low outlet flow, it is also the best column choice for GC-MS work.<\/p>\n\n\n\n<p><strong>Table V:&nbsp;<\/strong>General column characteristics based on ID.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td rowspan=\"2\"><strong>Characteristic<\/strong><\/td><td colspan=\"6\"><strong>Column Inner Diameter (mm)<\/strong><\/td><\/tr><tr><td><strong>0.10<\/strong><\/td><td><strong>0.15<\/strong><\/td><td><strong>0.18<\/strong><\/td><td><strong>0.25<\/strong><\/td><td><strong>0.32<\/strong><\/td><td><strong>0.53<\/strong><\/td><\/tr><tr><td>Nitrogen flow (mL\/min)<\/td><td>0.2<\/td><td>0.3<\/td><td>0.3<\/td><td>0.4<\/td><td>0.6<\/td><td>0.9<\/td><\/tr><tr><td>Helium flow (mL\/min)<\/td><td>0.6<\/td><td>0.8<\/td><td>1.0<\/td><td>1.4<\/td><td>1.8<\/td><td>3.0<\/td><\/tr><tr><td>Hydrogen flow (mL\/min)<\/td><td>0.7<\/td><td>1.1<\/td><td>1.8<\/td><td>1.8<\/td><td>2.3<\/td><td>3.7<\/td><\/tr><tr><td>Sample loading capacity (ng)<\/td><td>2.5<\/td><td>10<\/td><td>20<\/td><td>50<\/td><td>125<\/td><td>500<\/td><\/tr><tr><td>Theoretical plates\/meter<\/td><td>11,000<\/td><td>7000<\/td><td>6000<\/td><td>4000<\/td><td>3000<\/td><td>2000<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>Note: Flows listed are for maximum efficiency. Sample loading capacities are estimates only. Actual sample loading capacity varies with film thickness and analyte.<\/p>\n\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Tech Tip<\/h3>\n\n\n\n<p>When changing carrier gas flow rates, you must reconfirm peak identifications as elution order changes can occur.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Carrier Gas Type and Linear Velocity<\/h3>\n\n\n\n<p>Carrier gas choice and linear velocity significantly affect column separation efficiency, which is best illustrated using van Deemter plots (Figure 6). The optimum linear velocity for each gas is at the lowest point on the curve, where plate height (H) is minimized, and efficiency is maximized. As seen in Figure 6, the optimum linear velocities differ among common carrier gases.<\/p>\n\n\n\n<p>Nitrogen provides the best efficiency; however, the steepness of its van Deemter plot on each side of optimum means that small changes in linear velocity can result in large negative changes in efficiency. Compared to nitrogen, helium has a wider range for optimal linear velocity, but offers slightly less efficiency. In addition, because of its optimum velocity being faster, analysis times with helium are about half those when using nitrogen, and there is only a small sacrifice in efficiency when velocity changes slightly. Of the three common carrier gases, hydrogen has the flattest van Deemter curve, which results in the shortest analysis times and the widest range of average linear velocity over which high efficiency is obtained.<\/p>\n\n\n\n<p>Regardless of the type of gas used, the carrier gas head pressure is constant during column temperature programming, whereas the average linear velocity decreases during the run. For constant pressure work then, the optimal linear velocity should be set for the most critical separations. More common today, electronic pneumatic control (EPC) of carrier gas allows for constant flow or even constant linear velocity, which helps maintain high efficiency throughout a temperature programmed run.<\/p>\n\n\n\n<p>Another consideration for carrier gas type that is important, even if not directly related to column efficiency, is whether a mass spectrometer (MS) is used as a vacuum-outlet detector for GC. In almost all cases, helium is the carrier gas of choice, not only for its chromatographic efficiency but also because it is easier to pump than hydrogen. Hydrogen can be reactive in MS sources, leading to undesirable spectrum changes for some compounds. Nitrogen is typically not a carrier gas option for GC-MS, as it severely reduces sensitivity.<\/p>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><strong>Figure 6:<\/strong>\u00a0Operating carrier gas at the optimum linear velocity will maximize efficiency at a given temperature. Red circles indicate optimum linear velocities for each carrier gas<\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n<style>.kb-image45273_67205e-d1 .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<div class=\"wp-block-kadence-image kb-image45273_67205e-d1\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"564\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-06-1024x564.jpg\" alt=\"\" class=\"kb-img wp-image-20434\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-06-1024x564.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-06-300x165.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-06-768x423.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-06-1536x846.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-06.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/div>\n\n<\/div><\/div><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">GC Troubleshooting Tips<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Basic Steps<\/h3>\n\n\n\n<p>Follow these basic troubleshooting steps to isolate problems related to the sample, injector, detector, and column. Check the obvious explanations first and change only one thing at a time until you identify and resolve the problem.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Check the Obvious:<\/h3>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-829b1d53 wp-block-columns-is-layout-flex\" style=\"margin-bottom:0\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<ul class=\"wp-block-list\">\n<li>Power supply<\/li>\n\n\n\n<li>Electrical connections<\/li>\n\n\n\n<li>Signal connections<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<ul class=\"wp-block-list\">\n<li>Gas purity<\/li>\n\n\n\n<li>Gas flows<\/li>\n\n\n\n<li>Temperature settings<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<ul class=\"wp-block-list\">\n<li>Syringe condition<\/li>\n\n\n\n<li>Sample preparation<\/li>\n\n\n\n<li>Analytical conditions<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Identify the Cause:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Define the problem clearly; for example, \u201cOver the last 4 days, only the phenols in my sample have been tailing.\u201d<\/li>\n\n\n\n<li>Review sample and maintenance records to identify trends in the data or problem indicators, such as area counts decreasing over time or injector maintenance not being performed as scheduled.<\/li>\n\n\n\n<li>Use a logical sequence of steps to isolate possible causes.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Document Work and Verify System Performance:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Document all troubleshooting steps and results; this may help you identify and solve the next problem faster.<\/li>\n\n\n\n<li>Always inject a test mix and compare it to previous data to ensure restored performance.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Example Troubleshooting Sequence<\/h2>\n\n\n\n<p>An analyst observed that no peaks appeared during a GC-FID analysis. The flowchart below shows a logical progression of steps that can be used to identify the cause and correct the problem.<\/p>\n\n\n<style>.kb-image45273_43e6f6-2d:not(.kb-image-is-ratio-size) .kb-img, .kb-image45273_43e6f6-2d.kb-image-is-ratio-size{padding-top:var(--global-kb-spacing-xs, 1rem);padding-bottom:var(--global-kb-spacing-xs, 1rem);}.kb-image45273_43e6f6-2d .kb-image-has-overlay:after{opacity:0.3;}<\/style>\n<div class=\"wp-block-kadence-image kb-image45273_43e6f6-2d\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"414\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-02-1024x414.jpg\" alt=\"\" class=\"kb-img wp-image-70597\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-02-1024x414.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-02-300x121.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-02-768x311.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-02-1536x621.jpg 1536w, https:\/\/discover.restek.com\/wp-content\/uploads\/diagram-article-GNAR1724A-02.jpg 1800w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Symptoms and Solutions<\/h2>\n\n\n\n<p>Good chromatography is critical to obtaining accurate, reproducible results. Coelutions, asymmetric peaks, baseline noise, and other issues are common challenges in the GC laboratory. These analytical problems and others can be overcome by troubleshooting your separations using the tips below.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Poor Resolution<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\" style=\"border-width: 1px;\">\n<tbody>\n<tr>\n<td rowspan=\"5\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-01.jpg\" alt=\"Poor Resolution\" width=\"1000\" height=\"1058\" title=\"-\"><\/td>\n<td><strong><strong>Cause<\/strong><\/strong><\/td>\n<td><strong><strong>Solutions<\/strong><\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Non selective stationary phase<\/td>\n<td>\n<ul>\n<li>Choose appropriate stationary phase and column dimensions<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Poor efficiency<\/td>\n<td>\n<ul>\n<li>Optimize carrier gas linear velocity and GC oven temperature program.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Sample overload<\/td>\n<td>\n<ul>\n<li>Adjust sample concentration or amount on column.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Incorrect analytical conditions used<\/td>\n<td>\n<ul>\n<li>Verify temperature program, flow rates, and column parameters.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Poor Retention Time Reproducibility<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\" style=\"border-width: 1px;\">\n<tbody>\n<tr>\n<td rowspan=\"9\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-02.jpg\" alt=\"Poor Retention Time Reproducibility\" width=\"1000\" height=\"719\" title=\"-\"><\/td>\n<td><strong><strong><strong>Cause<\/strong><\/strong><\/strong><\/td>\n<td><strong><strong><strong>Solutions<\/strong><\/strong><\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Leaks<\/td>\n<td>\n<ul>\n<li>Leak check injector and press-fit connections.<\/li>\n<li>Replace critical seals (i.e., septa, O-rings, inlet disc, etc.).<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Analyte adsorption<\/td>\n<td>\n<ul>\n<li>Maintain inlet liner and GC column<\/li>\n<li>Use properly deactivated liners, seals, and columns.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Resolution\/integration issues<\/td>\n<td>\n<ul>\n<li>Avoid sample overload.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Incorrect column\/oven temperature program<\/td>\n<td>\n<ul>\n<li>Verify column temperature and oven temperature program.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Incorrect or variable carrier gas flow rate\/linear velocity<\/td>\n<td>\n<ul>\n<li>Verify the carrier gas flow and linear velocity.<\/li>\n<li>Repair or replace parts if necessary.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Poor control of oven temperature programming<\/td>\n<td>\n<ul>\n<li>Confirm GC oven program falls within instrument manufacturer\u2019s recommendation<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Incorrect oven equilibration time<\/td>\n<td>\n<ul>\n<li>Extend GC oven equilibration time.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>If manual injection, delay between pushing start and actual injection<\/td>\n<td>\n<ul>\n<li>Use autosampler or standardize manual injection procedure<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Fronting Peaks<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\" style=\"border-width: 1px;\">\n<tbody>\n<tr>\n<td rowspan=\"3\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-03.jpg\" alt=\"Fronting peaks\" width=\"1000\" height=\"817\" title=\"-\"><\/td>\n<td><strong><strong>Cause<\/strong><\/strong><\/td>\n<td><strong><strong>Solutions<\/strong><\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Incompatible stationary phase<\/td>\n<td>\n<ul>\n<li>Choose appropriate stationary phase<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Column overloading<\/td>\n<td>\n<ul>\n<li>Reduce amount injected, dilute sample.<\/li>\n<li>Increase column inner diameter and\/or film thickness.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Tailing Peaks<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"5\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-04.jpg\" alt=\"Tailing peaks\" width=\"1000\" height=\"817\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Adsorption due to surface activity or contamination<\/td>\n<td>\n<ul>\n<li>Use properly cleaned and deactivated liner, seal, and column.<\/li>\n<li>Trim inlet end of column.<\/li>\n<li>Replace column if damaged.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Adsorption due to chemical composition of compound<\/td>\n<td>\n<ul>\n<li>Derivatize compound.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Leak in system<\/td>\n<td>\n<ul>\n<li>Check for leaks at all connections, replace critical seals if needed.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Installation issues<\/td>\n<td>\n<ul>\n<li>Minimize dead volume.<\/li>\n<li>Verify that the column is cut properly (square).<\/li>\n<li>Verify correct installation distances.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Split Peaks<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"5\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-05.jpg\" alt=\"Split peaks\" width=\"200\" height=\"193\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Mismatched solvent\/stationary phase polarity<\/td>\n<td>\n<ul>\n<li>Adjust solvent or stationary phase to allow wetting.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Incomplete vaporization<\/td>\n<td>\n<ul>\n<li>Add surface area, such as wool, to the inlet liner to enhance vaporization.<\/li>\n<li>Use proper injector temperature.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Sample loading capacity exceeded<\/td>\n<td>\n<ul>\n<li>Inject less sample (dilute, use split injection, reduce injection volume).<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Fast autosampler injection into open liner<\/td>\n<td>\n<ul>\n<li>Use wool or slow injection speed.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Carryover\/Ghost Peaks<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"4\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-06.jpg\" alt=\"Carryover\/ghost peaks\" width=\"200\" height=\"377\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Contaminated syringe or rinse solvent<\/td>\n<td>\n<ul>\n<li>Replace rinse solvent.<\/li>\n<li>Rinse or replace syringe.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Backflash (sample volume exceeds liner volume)<\/td>\n<td>\n<ul>\n<li>Inject a smaller amount.<\/li>\n<li>Use a liner with a large internal diameter.<\/li>\n<li>Increase head pressure (i.e., flowrate) to contain the vapor cloud.<\/li>\n<li>Use slower injection rate.<\/li>\n<li>Lower inlet temperature.<\/li>\n<li>Increase split flow.<\/li>\n<li>Use liner with packing.<\/li>\n<li>Use pressure-pulse injection.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Last analysis ended too soon<\/td>\n<td>\n<ul>\n<li>Extend analysis time to allow all components and\/or matrix interferences to elute.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">High Bleed<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"4\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-07.jpg\" alt=\"High bleed\" width=\"200\" height=\"133\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Improper column conditioning<\/td>\n<td>\n<ul>\n<li>Increase conditioning time and\/or temperature.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<td>Contamination<\/td>\n<td>\n<ul>\n<li>Trim column and\/or heat to maximum temperature to remove contaminants.<\/li>\n<li>Replace carrier gas and\/or detector gas filters.<\/li>\n<li>Clean injector and detector.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<td>Leak in system and oxidation of stationary phase<\/td>\n<td>\n<ul>\n<li>Check for oxygen leaks across the entire system and replace seals and\/or filters.<\/li>\n<li>Replace column.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Unstable Baseline (Spiking, Noise, Drift)<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"8\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-08.jpg\" alt=\"Unstable baseline\" width=\"1000\" height=\"2017\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Carrier gas leak or contamination<\/td>\n<td>\n<ul>\n<li>Leak check connections and replace seals if needed.<\/li>\n<li>Replace carrier gas and\/or detector gas filters.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Injector or detector contamination<\/td>\n<td>\n<ul>\n<li>Clean system and perform regular maintenance.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Column contamination or stationary phase bleed<\/td>\n<td>\n<ul>\n<li>Condition, trim, and rinse column.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Septum coring\/bleed<\/td>\n<td>\n<ul>\n<li>Replace septum.<\/li>\n<li>Inspect inlet liner for septa particles and replace liner if needed.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Loose cable or circuit board connections<\/td>\n<td>\n<ul>\n<li>Clean and repair electrical connections.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Variable carrier gas or detector gas flows<\/td>\n<td>\n<ul>\n<li>Verify flow rates are steady and reproducible; may need to replace or repair flow controller.<\/li>\n<li>Leak check system.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Detector not ready<\/td>\n<td>\n<ul>\n<li>Allow enough time for detector temperatures and flows to equilibrate.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Response Variation<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"9\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-09.jpg\" alt=\"Response variation\" width=\"200\" height=\"238\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Sample issues<\/td>\n<td>\n<ul>\n<li>Check sample concentration.<\/li>\n<li>Check sample preparation procedure.<\/li>\n<li>Check sample decomposition\/shelf life.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Syringe problems<\/td>\n<td>\n<ul>\n<li>Replace syringe.<\/li>\n<li>Check autosampler operation.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Electronics<\/td>\n<td>\n<ul>\n<li>Verify signal settings and adjust if needed.<\/li>\n<li>Repair or replace cables or boards.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Dirty or damaged detector<\/td>\n<td>\n<ul>\n<li>Perform detector maintenance or replace parts.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Flow\/temperature settings wrong or variable<\/td>\n<td>\n<ul>\n<li>Verify steady flow rates and temperatures, then adjust settings and\/or replace parts if needed.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Adsorption\/reactivity<\/td>\n<td>\n<ul>\n<li>Remove contamination and use properly deactivated components.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Leaks<\/td>\n<td>\n<ul>\n<li>Check for leaks at all connections.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Change in sample introduction\/injection method<\/td>\n<td>\n<ul>\n<li>Verify injection technique and change back to original technique.<\/li>\n<li>Check that split ratio is correct.<\/li>\n<li>Verify that purge time or splitless hold time is correct.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">No Peaks<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"5\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-10.jpg\" alt=\"No peaks\" width=\"1000\" height=\"233\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Injection problems<\/td>\n<td>\n<ul>\n<li>Plugged syringe; clean or replace syringe.<\/li>\n<li>No sample; verify sample introduction.<\/li>\n<li>Injecting into wrong injector; reset autosampler.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Broken column<\/td>\n<td>\n<ul>\n<li>Replace column.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Column installed into wrong injector or detector<\/td>\n<td>\n<ul>\n<li>Re-install column.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Detector problems<\/td>\n<td>\n<ul>\n<li>Signal not recorded; check detector cables and verify that detector is turned on.<\/li>\n<li>Detector gas turned off or wrong flow rates; turn detector on and\/or adjust flow rates.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<h3 class=\"wp-block-heading\">Broad Peaks<\/h3>\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<tbody>\n<tr>\n<td rowspan=\"7\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/figure-article-GNAR1724A-chart-11.jpg\" alt=\"Broad peaks\" width=\"1000\" height=\"1700\" title=\"-\"><\/td>\n<td><strong>Cause<\/strong><\/td>\n<td><strong>Solutions<\/strong><\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>High dead volume<\/td>\n<td>\n<ul>\n<li>Minimize dead volume in the GC system; verify proper column installation, proper connectors, proper liners, etc.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Low flow rates<\/td>\n<td>\n<ul>\n<li>Verify injector and detector flow rates and adjust if needed.<\/li>\n<li>Verify make-up gas flow and adjust if needed.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Slow GC oven program<\/td>\n<td>\n<ul>\n<li>Increase GC oven programming rate.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Poor analyte\/solvent focusing<\/td>\n<td>\n<ul>\n<li>Lower GC oven start temperature.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Column film is too thick<\/td>\n<td>\n<ul>\n<li>Reduce retention of compounds by decreasing film thickness and length.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr style=\"vertical-align: top;\">\n<td>Sample carryover<\/td>\n<td>\n<ul>\n<li>See Carryover\/Ghost Peaks solutions.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Propel Method Development Forward with the Pro&nbsp;<em>EZ<\/em>GC Chromatogram Modeler<\/h3>\n\n\n\n<p>This improved version of our popular Pro&nbsp;<em>EZ<\/em>GC chromatogram modeler for polymer capillary columns is just as simple to use as the original, but it now offers advanced options for selecting phases, changing carrier gases and control parameters, further optimizing your results, and much more! Already a favorite of analysts around the world, the updated software helps you develop new methods or optimize existing ones more efficiently and effectively than ever before.<\/p>\n\n\n\n<p><em>In just seconds, you can generate a customized, interactive model chromatogram that matches real-world chromatograms with exceptional accuracy. Zoom in, view chemical structures, and even overlay the mass spectra of coeluting compounds.<\/em><\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"751\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/\/GNAR1724C-chromatogram-modeler-JP-1024x751.jpg\" alt=\"\" class=\"wp-image-24519\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-modeler-JP-1024x751.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-modeler-JP-300x220.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-modeler-JP-768x563.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-modeler-JP.jpg 1332w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h3 class=\"wp-block-heading\">Pro&nbsp;<em>EZ<\/em>GC Chromatogram Modeler<\/h3>\n\n\n\n<p><strong>YOU NEED:<\/strong>&nbsp;To develop a method from scratch, including the column<br>and conditions.<\/p>\n\n\n\n<p><strong>YOU HAVE:<\/strong>&nbsp;An analyte list (and you may have a column in mind, too).<\/p>\n\n\n\n<p><strong>YOU GET:<\/strong>&nbsp;Customized, interactive model chromatograms that provide a specific phase, column dimensions and conditions. You can change columns, modify conditions, zoom in, view chemical structures, and even overlay mass spectra of coeluting compounds.<\/p>\n\n\n\n<p><strong>Watch our instructional videos and get started today at&nbsp;<a href=\"https:\/\/ez.restek.com\/proezgc\" target=\"_blank\" rel=\"noopener\">www.restek.com\/proezgc<\/a><\/strong><\/p>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Modify Methods Quickly and with Confidence Using the&nbsp;<em>EZ<\/em>GC Method Translator and Flow Calculator<\/h3>\n\n\n\n<p>The&nbsp;<em>EZ<\/em>GC method translator and flow calculator tool makes it simple to switch carrier gases, change column dimensions or control parameters, or to optimize a method for speed or efficiency. Simply enter your method specifications, and the program will return a full set of calculated method conditions that will provide similar chromatography. Use the&nbsp;<em>EZ<\/em>GC method translator and flow calculator tool to optimize your analysis for speed so you can increase sample throughput!<\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"635\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/\/GNAR1724C-chromatogram-translator-and-calculator-JP-1024x635.jpg\" alt=\"\" class=\"wp-image-24525\" title=\"-\" srcset=\"https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-translator-and-calculator-JP-1024x635.jpg 1024w, https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-translator-and-calculator-JP-300x186.jpg 300w, https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-translator-and-calculator-JP-768x476.jpg 768w, https:\/\/discover.restek.com\/wp-content\/uploads\/GNAR1724C-chromatogram-translator-and-calculator-JP.jpg 1362w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h3 class=\"wp-block-heading\"><em>EZ<\/em>GC Method Translator and Flow Calculator<\/h3>\n\n\n\n<p><strong>YOU NEED:<\/strong>&nbsp;To switch carrier gases, to change column dimensions or control parameters, or to optimize a method for speed or efficiency.<\/p>\n\n\n\n<p><strong>YOU HAVE:<\/strong>&nbsp;An existing method.<\/p>\n\n\n\n<p><strong>YOU GET:<\/strong>&nbsp;A full set of calculated method conditions that will provide similar chromatography. Results include oven program and run time as well as average velocity, flow rate, splitless valve time, and other control parameters\u2014all in an easy-to-use, single-screen interface with seamless transfer between tools.<\/p>\n\n\n\n<p><strong>Start saving time today\u2014develop, optimize, or translate methods quickly and with confidence using Restek\u2019s EZGC online software suite!&nbsp;<a href=\"https:\/\/ez.restek.com\/ezgc-mtfc\" target=\"_blank\" rel=\"noopener\">www.restek.com\/ezgc-mtfc<\/a><\/strong><\/p>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:100px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Learn how to choose the right GC column the first time, optimize separations for the best balance of resolution and speed, and troubleshoot quickly based on chromatographic symptoms.<\/p>\n","protected":false},"author":11,"featured_media":7093,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"footnotes":""},"categories":[7],"tags":[],"industries-application":[],"post-badge":[],"resource-type":[567],"product-library":[2372,2384],"resource-technique":[2294],"ppma_author":[414],"class_list":["post-45273","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-articles","resource-type-selection-guides","product-library-gas-chromatography-products","product-library-gc-columns","resource-technique-gas-chromatography-gc"],"acf":[],"taxonomy_info":{"category":[{"value":7,"label":"Articles"}],"resource-type":[{"value":567,"label":"Selection 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