Analysis of organochlorine pesticides in contaminated soil by GC-MS/MS using accelerated solvent extraction as a green sample preparation

Abstract

ABSTRACT Organochlorine pesticides (OCPs), persistent organic pollutants, in the contaminated soil have been analysed by a gas chromatography-tandem mass spectrometry (MS) in this work. OCPs were extracted with a mixture of dichloromethane and n-hexane by using accelerated solvent extraction at elevated temperature and high pressure. The extractant was concentrated by a rotary vacuum evaporator and cleaned up by silica gel solid phase extraction. OCPs were then separated by a gas chromatography in combination with an electron impact ionisation MS in MS/MS mode. The limit of detection, limit of quantification and other important parameters of the GC-EI-MS/MS analytical method, such as repeatability, recovery and so on, have been investigated and presented. Limit of detection and limit of quantification have been achieved from 0.005 ng g−1 (p,p’-DDE) to 0.405 ng g−1 (dieldrin) and 0.016 ng g−1 to 1.216 ng g−1, respectively. The repeatability of this method was achieved below 8.3% and 13.7% for short- and long-term stability. Recovery of all OCPs ranged from 78.1% ± 1.5% to 117.5% ± 3.2%. The developed analytical method was validated by spiking experiments in the real samples. The validated method has been then used for the analysis of OCPs in the soil samples that were collected from the contaminated areas in Vietnam. Results showed the presence of hexachlorocyclohexane isomers and p-p’-DDT in all analysed samples at elevated levels.