Determination of 7 Common Insecticides in Edible Flowers by Gas Chromatography-Tandem Mass Spectrometry with QuEChERS

The QuEChERS automatic sample preparation system was used for extraction and purification, and gas chromatography-tandem mass spectrometry was proposed to determine the 7 insecticides in edible flowers, including dicofol, myclobutanil, tdyfluanid, cyflutenamid, pirimicarb, fenitrothion and pyridalyl. Acetonitrile (20 mL) and an extraction package (4 g of anhydrous magnesium sulfate, 1 g of sodium chloride, 1 g of sodium citrate, and 0.5 g of disodium citrate) were added into 10 g of edible flower sample. After shaking, purification agents (500 mg of magnesium sulfate, 150 mg of N-propylethylenediamine, and 15 mg of graphitized carbon black) were added, and automatic extraction and purification were performed according to the program. The mixture was centrifuged, and the supernatant was blown to near dryness by nitrogen. The residue was dissolved by acetone, and targets in the resulting solution was separated using the Rtx-5MS chromatographic column under programmed heating conditions, ionized by electron impact ion source, and detected using the multiple reaction monitoring mode. It was shown that linear relationships between values of the mass concentration and the peak area of the 7 insecticides were kept in the range of 0.005-5.0 mg·mL^-1, with lower limits of determination (10S/N) in the range of 0.007 6-0.029 mg·kg^-1. Test for recovery was made according to the standard addition method, giving recoveries in the range of 83.2%-116%, and RSDs (n=6) of the determined values were less than 5.0%. The proposed method was used for the analysis of 9 batches of edible flower samples, and the detection rate of dicofol was relatively high, with detection amount (0.013 mg·kg^-1) of dicofol in only one batch of sample exceeding its lower limit of determination (0.007 6 mg·kg^-1).