Analysis of low-volatility pesticides in cabbage by high temperature comprehensive two-dimensional gas chromatography

High-temperature comprehensive two-dimensional gas chromatography (HTGC x GC) using a longitudinally modulated cryogenic system (LMCS) was developed for the analysis of low-volatility pesticides in cabbage. The method applied DB-17HT and DB-5HT as the first and second dimensional (D-1 and D-2) columns, respectively. Twelve pesticides, namely 6 organochlorines (4,4 '-DDT, beta-endosulfan, endosulfan sulfate, endrin, heptachlor, and dicofol), 4 carbamates (metolcarb, isoprocarb, methiocarb, and carbofuran), 1 organophosphate (chlorpyrifos), and 1 pyrethroid (permethrin), were spiked into cabbage samples and prepared using QuEChERS. The applied oven temperature was up to 340 degrees C, enabling the elution of all the target pesticides and the matrix. The effects of initial oven temperature program, temperature ramp rate, LMCS trap temperature, and modulation period (P-M) on the separation results were investigated, leading to the suitable conditions of 80 degrees C, 15 degrees C min(-1), 10 degrees C, and 12 s, respectively. The method detection limits, signal-to-noise ratio, and recoveries of the compounds were within the ranges of 0.01-0.09 mg kg(-1), 4.26-32.7, and 78-104%, respectively. Good linearity ranges within the concentration range of 0.1-1 ppm with R-2 > 0.9134 were also obtained with the intra and interday precisions of the peak areas of 0.4-9.8% and 1.0-10.2%, respectively.

Automated summary

A high-temperature comprehensive two-dimensional gas chromatography method using a longitudinally modulated cryogenic system was developed for analyzing low-volatility pesticides in cabbage. The method achieved efficient separation of target pesticides and matrix and yielded satisfactory analytical results by optimizing experimental conditions.