Determination of Residues of 3 Quinoline Fungicides in Fruit Tree Planting Soil by High Performance Liquid Chromatography-Tandem Mass Spectrometry with Fully Automatic Accelerated Solvent Extraction and Solid Phase Extraction

A method for the determination of residues of 3 quinoline fungicides, including chinomethionat, dichloroanthraquinone and ethoxyquin, in fruit tree planting soil by high performance liquid chromatography-tandem mass spectrometry with fully automatic accelerated solvent extraction and solid phase extraction. The pretreated soil sample powder (10.0 g) was taken, and about 10 g of diatomite was added. After mixing well, the mixture was placed into a accelerated solvent extraction tank, and the extraction was conducted at extraction temperature of 70 ℃ and extraction time of 8 min. The extracting solution was blown to 5 mL by nitrogen, then purified by activated HLB solid phase extraction column. After rinsing and eluting, the eluate was blown to near dryness by nitrogen, and its volume was made up to 1 mL with acetonitrile. The mixed solution was filtered by 0.45 μm filter membrane, and 3 quinoline fungicides in the filtrate was determined by HPLC-MS/MS, using Shimadzu Venusil MP C₁₈ column as the stationary phase, and the mixed solution of 0.1% (volume fraction) formic acid solution and methanol at different volume ratios as the mobile phase for gradient elution. Targets seperated were scanned by the positive ion mode of the electrospray ion source, and deteted by the multiple reaction monitoring mode. It was shown that linear relationships between the mass concentrations and corresponding response values of the 3 targets were kept in definite ranges, with detection limits (3S/N) in the range of 0.05-0.13 μg · kg^-1. The recovery of the 3 targets ranged from 87.3% to 103% at 3 spiked concentration levels, with RSDs (n=6) of the determined values less than 4.0%.