GC-MS Determination of Residual Amounts of Pesticides in Vegetables and Fruits with Head-Space Solid-Phase Microextraction

HS-SPME-GC-MS was applied to the determination of residual amounts of 15 pesticides in vegetables and fruits. The optimized conditions found were as follows: ① 100 μm PDMS micro-extractor was used; ② concentration of salt ion: 30% (w) NaCl; ③ temperature of extraction: 70 ℃±1 ℃; ④ time of extraction: 30 min. HP-5MS column was used for GC separation, and mode of full-scanning as well as selected ion monitoring were adopted in MS determination. Linear relationships between values of peak area and mass concentration of the 15 pesticides were kept in the same range of 0.05-1.0 mg·L-1, with detection limits (3S/N) in the range of 0.02-0.10 μg·kg-1. Tests for recovery were made using 2 fruit samples as matrixes by standard addition method at 3 concentration levels of 0.05, 0.2, 0.5 mg·kg-1, giving values of recovery and RSD′s (n=5) in the ranges of 71.0%-96.0% and 0.5%-9.8% respectively.