On the surface, alcohol analyses appear relatively straightforward. They involve few target analytes, are not extremely sensitive, and have quick sample preparation. However, they are not as simple as they seem. Ethanol analyses present distinct chromatography challenges when assaying in biological samples. Compounds found in biological matrices can interfere with the identification and quantitation of ethanol and its associated analytes.<\/p>\n\n\n\n
Restek has developed tailored columns to address the common analyte interferences that can hinder productive chromatography. Dual capillary column sets for GC are available for common blood alcohol analyses, and high-throughput analytical LC column and guard cartridges are available for urinary alcohol assays. Starting method development with tailored columns designed specifically to lessen interferences can help labs develop methods faster and keep instruments running.<\/p>\n\n\n\n
Gas chromatography coupled with headspace sampling and a flame ionization detector (HS-GC-FID) is the most commonly used technique for the analysis of blood alcohol in biological specimens from both living and dead persons. HS-GC-FID is remarkedly simple, reliable, and linear over the analytical range needed for the quantitative detection of alcohol. The troublesome part of the chromatographic analysis is ensuring analyte specificity from endogenous compounds. This is extremely important when analyzing postmortem samples due to the risk that fermentation or putrefaction may produce volatile chemical byproducts that can interfere with the analysis. For this reason, it is always recommended to use a dual column method. By splitting the sample after the injection port and analyzing it simultaneously on two different stationary phases, we can both quantify and confirm the analyte’s identity in a single run (Figure 1). The target analytes will elute in the calibrated retention time window on both columns, thus confirming a positive identification. To simplify column selection, Restek has paired two distinct sets of column phases: Rtx-BAC1 and Rtx-BAC2 columns and Rtx-BAC Plus 1 and Rtx-BAC Plus 2 columns for in vivo and postmortem analysis.<\/p>\n\n\n