Gas chromatographic determination of pesticide residues using electron-capture detector and mass spectrometry

The sensitive and reliable method for determination of 6 pesticides, cyanazine (triazine), uniconazole (azole), diflufenican (nicotinilide), vernolate (thiocarbamate), bromoxynil (hydroxyl benzonitrile), and asulam (sulfanilyl carbamate) were examined and validated. The methods based on solid-phase extraction (SPE) and gas chromatograph (GC) with electron capture detection (ECD). Confirmation analysis of pesticides was carried out by GC-MS in the selected ion monitoring (SIM) mode using 2 target ions. Method validation was performed at 5 fortification levels (0. 005, 0. 01, 0. 05, 0. 1, and 0. 5 mg/L). The linearity of the calibration curves was excellent in matrix matched standards, and yielded the coefficients of determination (R ²)≥0. 9982 for all target analytes. The limit of quantification (LOQ) was 0. 05 mg/L for 6 pesticide compounds and the reporting level of the method, defined as lower than the maximum residue levels established by Korea Food & Drug Administration (KFDA). Average recoveries of the pesticides spiked at 0. 05, 0. 1, and 0. 5 mg/L into 3 agricultural products, rice, apple, and soybean were in the range 76. 40-120% with relative standard deviation (RSD) values ≤11. 07% for all compounds, respectively.