Residual Analysis of Organochlorine Pesticides in Soil by Gas Chromatograph–Electron Capture Detector (GC–ECD) and Gas Chromatograph–Negative Chemical Ionization Mass Spectrometry (GC–NCI–MS)

Abstract

Gas chromatograph–electron capture detector (GC–ECD) and gas chromatograph–negative chemical ionization mass spectrometry (GC–NCI–MS) were applied to determine the residues of 20 organochlorine pesticides (OCPs) in soil after Soxhlet extraction with hexane/acetone (v: v = 1: 1) followed by cleanup with Florisil solid phase extraction (SPE) column (Palo Alto, CA). The method parameters for two different detection systems, including linear range, precision, detection limit and recovery, were studied and compared. The detection limit was in the range from 0.027 to 0.098 μ g/kg detected by GC–ECD and from 1.5 × 10− 4–2.4 × 10− 3μ g/kg detected by GC–NCI–MS for 20 OCPs in soil. The average recoveries of spiked sample ranged from 70.0% to 127% for GC–ECD and from 73.0%–122% for GC–NCI–MS, respectively. The results indicated that the method of GC–NCI–MS was more sensitive and selective than GC–ECD for determination of OCPs in soil.