Determination of organochlorine pesticides in river water by gas chromatography-negative-ion chemical-ionization mass spectrometry using large volume injection

Abstract

A method for the determination of 24 organochlorine pesticides by gas chromatography-mass spectrometry (GC-MS) with negative-ion chemical-ionization (NICI) using programmable temperature vaporizer (PTV)-based large volume injection (LVI) is described. The ion source temperature was determined to be 150 °C for the optimized NICI-selected ion monitoring (SIM) conditions. PTV inlet parameters were also optimized. The sensitivities of the pesticides by splitless-GC-NICI-MS were approximately 7.8–360 times higher than those of the pesticides by splitless-GC-EI-MS. The sensitivities of the pesticides by LVI-GC-NICI-MS were over 80 times higher than those of the pesticides by spiltless-GC-NICI-MS. This method was applied to the determination of the pesticides in river water using micro liquid–liquid extraction as sample preparation. The recoveries of the pesticides from a river water sample spiked with standards at 2 ng l⁻¹ and 20 ng l⁻¹were 75–111% (RSD, 2.9–15%) and 92–105% (RSD, 0.5–5.6%), respectively. The methodical detection limits ranged from 0.004 to 2.2 ng l⁻¹