SPE-GC-MS Determination of Residual Amounts of 15 Pesticides in Drinking Water

Pesticides in the water sample (1.00 L) were enriched with a flow rate of 10 mL·min^-1 on activated C₁₈ solid phase extraction column and the analytes were eluted from the column with 15.0 mL of ethyl acetate. The eluate was dehydrated with anhydrous sodium sulfate, concentrated and dried by nitrogen blowing. The residue was taken up with ethyl acetate and made up its volume to 1.0 mL, and the solution was filtered. After separation by GC, MS analysis was carried out under the condition of EI and SIM. Linear relationships between values of peak area and mass concentration of the 15 pesticides were found in the same range of 1.00-50.0 μg·L^-1, with detection limits (3S/N) in the range of 0.05-0.21 μg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 90.4%-98.8%, with RSDs (n=6) ranged from 1.1% to 2.7%.