![\"THCA](\"https:\/\/discover.restek.com\/wp-content\/uploads\/blog-accurate-quantification-of-cannabinoid-acids-by-gc-is-it-possible-01-1024x387.jpg\" "\\"-\\"")
<\/figure>\n\n\n\nWhile HPLC would be the more straightforward choice for cannabis or hemp potency analysis, some labs only have GC instruments. Joan Serdar at ARRO Laboratories, Inc. is one such analyst. Her lab is equipped with GC instruments, but she wants to accurately quantify both the neutral and acidic forms of cannabinoids in hemp and cannabis \u2013 good for you, Joan! In working with Joan, we were able to take a page from the toxicologists\u2019 handbook and derivatize our cannabinoids. What is derivatization, you ask? In a nutshell, derivatization prior to GC analysis involves \u2018sticking\u2019 functional groups onto a molecule in order to make it more volatile, more stable, or to improve detectability.<\/p>\n\n\n\n
In the case of our cannabinoids, we want to make them more stable so the acidic forms don\u2019t convert to their neutral forms in our GC inlet (see figure above). The derivatization technique we decided to try for this analysis involves N,O-Bis(trimethylsilyl)trifluoracetamide + 1% trimethylchlorosilane (BSTFA + 1% TMCS). This derivatization reagent targets \u2013OH groups and replaces the hydrogen in that group with a trimethylsilyl group, creating an ether that is easier to gas chromatograph than an acid or alcohol.<\/p>\n\n\n\n
Hydroxyl (-OH) Groups on Cannabinoids are Derivatized Using BSTFA + 1% TMCS, Making Them Stable in the GC Injection Port<\/strong><\/p>\n\n\n\n So did it work? The preliminary work performed by ARRO Laboratories\u00a0and here at Restek indicates that this derivatization technique works for all of the cannabinoids of interest for most scientists, resulting in stable, chromatographically-resolved derivatization products. The chromatogram below is a derivatized high-level standard analyzed by my colleague Jack Cochran via GC-FID using the same 15m x 0.25mm x 0.25\u00b5m Rxi-35Sil MS column we recommend for underivatized cannabis potency work. The\u00a0Rxi-35Sil MS\u00a0<\/a>had the selectivity needed to separate all of the derivatized cannabinoids. Jack also ran the sample by GC-TOFMS to verify peak IDs and ensure we were getting the derivatization products we hoped to get.<\/p>\n\n\n\n GC-FID Chromatogram of Derivatized Cannabinoid Acids and Neutrals \u2013 All Compounds are Resolved on Rxi-35Sil MS<\/strong><\/p>\n\n\n\n So these results look pretty promising! While HPLC is a more straightforward way to measure cannabinoids, the derivatization used here was very simple and shows really good preliminary results. Stay tuned for more discussion of this method \u2013 does it work in the presence of matrix? Find out in our next installment (spoiler alert: it does).<\/p>\n\n\n\n![\"BSTFA](\"https:\/\/discover.restek.com\/wp-content\/uploads\/blog-accurate-quantification-of-cannabinoid-acids-by-gc-is-it-possible-02-1024x336.jpg\" "\\"-\\"")
<\/figure>\n\n\n\n![\"GC-FID](\"https:\/\/discover.restek.com\/wp-content\/uploads\/blog-accurate-quantification-of-cannabinoid-acids-by-gc-is-it-possible-03-1024x779.jpg\" "\\"-\\"")
<\/figure>\n\n\n\nProducts Mentioned<\/h3>\n
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