DETERMINATION OF ETHION RESIDUES IN SOIL BY EXTRACTION AND BY MASS-SPECTROMETRY USING DIFFERENT PROCEDURES

Optimized experimental procedures including time of extraction, extrac tion solvent in Soxhlet extraction technique were sought for detection of trace ethion residues in soil. The largest recoveries over 96% wer e achieved with a 1:1 mixture of methanol and acetone as extraction so lvent for three hours. In comparing EI, CI, EI-CAD, and PCI-CAD modes of a four sector mass spectrometry for detection ethion, it was shown the best monitoring mode to be EI monitoring of the M(+.) of ethion, m /z 384, which fragments to give the m/z 231 product ion. The limit of detection obtained was 170 pg/g in soil.