{"id":43520,"date":"2020-10-20T00:00:00","date_gmt":"2020-10-20T00:00:00","guid":{"rendered":"https:\/\/discover.restek.com\/uncategorized\/lc-msms-analysis-of-paraquat-and-diquat-without-ion-pairing-reagents\/"},"modified":"2026-02-17T20:01:07","modified_gmt":"2026-02-17T20:01:07","slug":"lc-msms-analysis-of-paraquat-and-diquat-without-ion-pairing-reagents","status":"publish","type":"post","link":"https:\/\/discover.restek.com\/es\/articles\/evss2791\/lc-msms-analysis-of-paraquat-and-diquat-without-ion-pairing-reagents","title":{"rendered":"LC-MS\/MS Analysis of Paraquat and Diquat without Ion-Pairing Reagents"},"content":{"rendered":"\n<ul class=\"wp-block-list\">\n<li>Good retention and peak shape without system contamination from ion-pairing reagents.<\/li>\n\n\n\n<li>Consistent resolution and response with MS-friendly mobile phases.<\/li>\n\n\n\n<li>Fast, 7-minute gradient method supports high sample throughput.<\/li>\n<\/ul>\n\n\n\n<p>Paraquat is a fast-acting, nonselective contact herbicide that is relatively inexpensive. These characteristics have led to its widespread use on agricultural crops in much of the developing world. While paraquat is reasonably safe to apply with proper precautions, accidental or deliberate ingestion has an extremely high fatality rate. Largely for this reason, paraquat has been restricted in many countries. Diquat is a related herbicide that is often formulated with paraquat and is monitored due to its potential toxic effects on the central nervous system. LC-MS\/MS analysis of paraquat and diquat in low-moisture food crops, drinking water, and surface water is an important tool for preventing or limiting human and environmental exposure.<\/p>\n\n\n\n<p>Typically, LC-MS\/MS analysis of paraquat and diquat involves the use of ion-pairing reagents in order to achieve adequate retention, resolution, and peak shape. However, ion-pairing reagents are known to compete with target analytes for ionization, which typically results in reduced sensitivity. These reagents can also contaminate the LC-MS\/MS system, requiring that it be taken off-line frequently for extensive cleaning.<\/p>\n\n\n\n<p>Here, we have developed an LC-MS\/MS analysis of paraquat and diquat that does not use ion-pairing reagents, but still provides good retention and peak shape. Both target analytes were fully resolved and showed much greater sensitivity at 50 ng\/mL (50 ppb) compared to ion-pairing methods. This fast, 7-minute analysis provided consistent MS results using a 50 mM buffered mobile phase, which is within the buffer salt concentration limits that are generally recommended to minimize contamination and maintenance for LC-MS\/MS systems.<\/p>\n\n\n<div class=\"wp-block-custom-chromatogram-article-top\"><div class=\"chromatogram-article-placeholder\"><div class=\"figure-heading\"><\/div><div class='chromatogram-article-inner-full'><div class=\"chromatogram-article-inner\">\n<div class=\"wp-block-custom-chromatogram-article\"><div class=\"wp-block-custom-chromatogram-article\"><div class=\"chromatogram-image regular-image\"><img decoding=\"async\" src=\"https:\/\/ez.restek.com\/images\/cgram\/lc_fs0512.png\" alt=\"Paraquat and Diquat on Raptor HILIC-Si\" title=\"-\"><\/div><p class=\"article-id\" style=\"text-align:center\"> LC_FS0512<\/p><div class=\"chromatogram-peaks\"><h4>Peaks<\/h4><table class=\"peaks col-12\">\n<thead><tr><th><\/th><th style=\"text-align: left;width: 75px\">Peaks<\/th><th style=\"text-align: center;width: 75px\">t<sub>R<\/sub> (min)<\/th><th style=\"text-align: center;width: 75px\">Precursor Ion 1<\/th><th style=\"text-align: center;width: 75px\">Product Ion 1<\/th><th style=\"text-align: center;width: 75px\">Precursor Ion 2<\/th><th style=\"text-align: center;width: 75px\">Product Ion 2<\/th><\/tr><\/thead>\n<tbody><tr><td class=\"num\">1.<\/td><td class=\"cmpd\"><a class=\"cmpd_link\" title=\"View compound information for Diquat\" href=\"https:\/\/ez.restek.com\/compound\/view\/en\/6385-62-2\/Diquat\" target=\"_blank\" rel=\"noopener\">Diquat<\/a><\/td><td class=\"oth\">3.25<\/td><td class=\"oth\">183.3<\/td><td class=\"oth\">157.2<\/td><td class=\"oth\">183.3<\/td><td class=\"oth\">130.1<\/td><\/tr>\n<tr><td class=\"num\">2.<\/td><td class=\"cmpd\"><a class=\"cmpd_link\" title=\"View compound information for Paraquat\" href=\"https:\/\/ez.restek.com\/compound\/view\/en\/1910-42-5\/Paraquat\" target=\"_blank\" rel=\"noopener\">Paraquat<\/a><\/td><td class=\"oth\">3.46<\/td><td class=\"oth\">185.3<\/td><td class=\"oth\">170.3<\/td><td class=\"oth\">171.3<\/td><td class=\"oth\">77.2<\/td><\/tr>\n<\/tbody><\/table><\/div><div class=\"chromatogram-conditions\"><h4>Conditions<\/h4><div class=\"conditions-container container-fluid\"><div class=\"row\"><table class=\"conditions col-lg-6 col-12\"><tr><th class=\"conditions_header\" scope=\"row\">Column<\/th><td>Raptor HILIC-Si  (<a target=\"_blank\" href=\"https:\/\/www.restek.com\/p\/9310A52?utm_source=chromatograms&amp;utm_medium=link&amp;utm_campaign=LC_FS0512\" rel=\"noopener\">cat.# 9310A52<\/a>)<\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Dimensions:<\/th><td>50 mm x 2.1 mm ID<\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Particle Size:<\/th><td>2.7 \u00b5m<\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Pore Size:<\/th><td>90 \u00c5<\/td><\/tr><tr><td><\/td><tr><th class=\"sub conditions_header\" scope=\"row\">Temp.:<\/th><td>45 \u00b0C<\/td><\/tr><tr class=\"cgram_header_row\"><th class=\"conditions_header\" scope=\"row\">Standard\/Sample<\/th><td>Paraquat &amp; diquat calibration mix (<a target=\"_blank\" href=\"https:\/\/www.restek.com\/p\/32437?utm_source=chromatograms&amp;utm_medium=link&amp;utm_campaign=LC_FS0512\" rel=\"noopener\">cat.# 32437<\/a>)<\/td><\/tr>\n<tr><th class=\"sub conditions_header\" scope=\"row\">Diluent:<\/th><td>Mobile phase B<\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Conc.:<\/th><td>50 ng\/mL<\/td><\/tr><td><\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Inj. Vol.:<\/th><td>5 \u00b5L <\/td><\/tr><tr class=\"cgram_header_row\"><th class=\"conditions_header\" scope=\"row\">Mobile Phase<\/th><td><\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">A:<\/th><td>Water, 50 mM ammonium formate, 0.5% formic acid <\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">B:<\/th><td>25:75 Water:acetonitrile, 50 mM ammonium formate, 0.5% formic acid <\/td><\/tr><tr><td><\/td><td><table class=\"cgram_ramp\"><thead><tr><th>Time (min)<\/th><th>Flow (mL\/min)<\/th><th>%A<\/th><th>%B<\/th><\/tr><\/thead><tbody><tr><td>0.00<\/td><td>0.6<\/td><td>0<\/td><td>100<\/td><\/tr><tr><td>4.00<\/td><td>0.6<\/td><td>35<\/td><td>65<\/td><\/tr><tr><td>4.01<\/td><td>0.6<\/td><td>0<\/td><td>100<\/td><\/tr><tr><td>7.00<\/td><td>0.6<\/td><td>0<\/td><td>100<\/td><\/tr><\/tbody><\/table><\/td><\/tr><\/table><table class=\"conditions col-lg-6 col-12\"><tr><th class=\"conditions_header\" scope=\"row\">Detector<\/th><td>MS\/MS<\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Ion Mode:<\/th><td>ESI+ <\/td><\/tr><tr><th class=\"sub conditions_header\" scope=\"row\">Mode:<\/th><td>MRM <\/td><\/tr><tr class=\"cgram_header_row\"><th class=\"conditions_header\" scope=\"row\">Instrument<\/th><td>HPLC<\/td><\/tr><\/table><\/div><\/div><\/div><div class=\"chromatogram-pdf-link\"><a href=\"https:\/\/ez.restek.com\/images\/cgram\/lc_fs0512.pdf\" target=\"_blank\" rel=\"noopener noreferrer\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"18\" height=\"18\" viewBox=\"0 0 18 18\"><g data-name=\"Group 2996\"><path data-name=\"Rectangle 1246\" d=\"M0 0h18v18H0z\" style=\"fill: none;\"><\/path><\/g><g data-name=\"Group 2997\"><path data-name=\"Path 729\" d=\"M13.412 11.4v2.017H5.345V11.4H4v2.017a1.349 1.349 0 0 0 1.345 1.345h8.068a1.349 1.349 0 0 0 1.345-1.345V11.4zm-.672-2.694-.948-.948-1.741 1.735V4H8.706v5.493L6.965 7.758l-.948.948 3.361 3.361z\" transform=\"translate(-.437 -.414)\" style=\"fill: rgb(13, 123, 196);\"><\/path><\/g><\/svg>Download PDF<\/a><\/div><\/div><\/div>\n<\/div><\/div><\/div>\n\n\n<div style=\"height:100px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n","protected":false},"excerpt":{"rendered":"<p>LC-MS\/MS analysis of paraquat and diquat herbicides is an important tool for protecting human and environmental health. However, the ion-pairing reagents that are commonly used to improve retention, resolution, and peak shape have a negative impact on sensitivity and can contaminate the system necessitating frequent cleaning. The LC-MS\/MS analysis of paraquat and diquat presented here provides complete separation and good peak response for both target analytes in a fast, 7-minute gradient run without the use of troublesome ion pairing reagents.<\/p>\n","protected":false},"author":11,"featured_media":6781,"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":[2163,2161,2668],"post-badge":[],"resource-type":[2623],"product-library":[2391,2373,2399,2374],"resource-technique":[2299,2301,2302],"hf_cat_post":[650,2624],"ppma_author":[414],"class_list":["post-43520","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-articles","industries-application-drinking-water-wastewater-testing","industries-application-environmental","industries-application-semivolatiles","resource-type-featured-application","product-library-lc-columns","product-library-liquid-chromatography-products","product-library-liquid-reference-standards","product-library-reference-standard-products","resource-technique-liquid-chromatography","resource-technique-mass-spectrometry-ms","resource-technique-ms-ms"],"acf":[],"taxonomy_info":{"category":[{"value":7,"label":"Articles"}],"industries-application":[{"value":2163,"label":"Drinking Water &amp; Wastewater Testing"},{"value":2161,"label":"Environmental"},{"value":2668,"label":"Semivolatiles"}],"resource-type":[{"value":2623,"label":"Featured Application"}],"product-library":[{"value":2391,"label":"LC Columns"},{"value":2373,"label":"Liquid Chromatography Products"},{"value":2399,"label":"Liquid Reference Standards"},{"value":2374,"label":"Reference Standard Products"}],"resource-technique":[{"value":2299,"label":"Liquid Chromatography"},{"value":2301,"label":"Mass Spectrometry (MS)"},{"value":2302,"label":"MS\/MS"}]},"featured_image_src_large":["https:\/\/discover.restek.com\/wp-content\/uploads\/feature-EVSS2791-1024x536.jpg",1024,536,true],"author_info":{"display_name":"Restek Corporation","author_link":"https:\/\/discover.restek.com\/es\/author\/restek-corporation\/"},"comment_info":0,"category_info":[{"term_id":7,"name":"Articles","slug":"articles","term_group":0,"term_taxonomy_id":7,"taxonomy":"category","description":"","parent":0,"count":468,"filter":"raw","cat_ID":7,"category_count":468,"category_description":"","cat_name":"Articles","category_nicename":"articles","category_parent":0}],"tag_info":false,"authors":[{"term_id":414,"user_id":11,"is_guest":0,"slug":"restek-corporation","display_name":"Restek Corporation","avatar_url":{"url":"https:\/\/discover.restek.com\/wp-content\/uploads\/Restek_Favicon_300x300.jpg","url2x":"https:\/\/discover.restek.com\/wp-content\/uploads\/Restek_Favicon_300x300.jpg"},"0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/posts\/43520","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/comments?post=43520"}],"version-history":[{"count":8,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/posts\/43520\/revisions"}],"predecessor-version":[{"id":87661,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/posts\/43520\/revisions\/87661"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/media\/6781"}],"wp:attachment":[{"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/media?parent=43520"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/categories?post=43520"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/tags?post=43520"},{"taxonomy":"industries-application","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/industries-application?post=43520"},{"taxonomy":"post-badge","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/post-badge?post=43520"},{"taxonomy":"resource-type","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/resource-type?post=43520"},{"taxonomy":"product-library","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/product-library?post=43520"},{"taxonomy":"resource-technique","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/resource-technique?post=43520"},{"taxonomy":"hf_cat_post","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/hf_cat_post?post=43520"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/discover.restek.com\/es\/wp-json\/wp\/v2\/ppma_author?post=43520"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}