Analysis of etoxazole in red pepper after major modification of QuEChERS for gas chromatography–nitrogen phosphorus detection

A major modification to the QuEChERS (quick, easy, cheap, effective, rugged and safe) method was developed for the analysis of etoxazole in red pepper using gas chromatography coupled with a nitrogen–phosphorus detector. Etoxazole was extracted with acetonitrile, partitioned with magnesium sulfate and purified with a solid‐phase extraction cartridge. The method showed good linearity with a determination coefficient ( R 2 ) of 0.998 for the 0.02–2.0 mg/L concentration range. The method was validated using blank red pepper spiked at 0.2 and 1.0 mg/kg, and the average recovery rate was 74.4–79.1% with relative standard deviations <5% for intra‐ and inter‐day precision. The limits of detection and quantification were 0.007 and 0.02 mg/kg, respectively. The developed method was successfully applied to field‐incurred samples, and the presence of etoxazole residues was confirmed using gas chromatography/mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.