GC Determination of Organophosphorus Pesticides in Water with Solid Phase Extraction

A method of GC for the determination of 10 organophosphorus pesticides with different polarity in water was proposed. Acidity of water sample (50 mL) was adjusted to pH 3-5 with HCl (1+1) solution, and the sample solution was extracted on LiChrolut EN Merck solid phase extraction column (SPE). Then organophosphorus pesticides on the SPE column were eluted in succession with acetone (2 mL), acetonitrile (2 mL) and CH2Cl2 (2 mL); and the eluate obtained was purified on graphitized carbon black column. The carbon black column was eluted with 3 mL each of acetonitrile and acetone, and the eluate was used for GC analysis. DB17 capillary column was used for separation, and FTD was used for determination. Linearity ranges for the 10 organophosphorus pesticides were found to be same between of 0.1-4.0 μg·L-1, with detection limit (3s) in the range of 0.10-0.30 μg·L-1. The proposed method was applied to the determination of organophosphorus pesticides in water sample, giving values of recovery by standard addition method in the range of 78.8%-102% with RSD′s (n=7) in the range of 1.7%-7.4%.