Organochlorine Pesticides and Degradation Products in Soil around a Former Formulation Plant in Morogoro Municipality, Tanzania

Abstract

The levels and compositions of organochlorine pesticides and degradation products in soil samples collected from a former formulation plant in Morogoro municipality, Tanzania, were determined. Extraction was performed by pressurized fluid extraction using n-hexane:acetone (75:25) mixture. Clean-up of extracts was conducted by using silica gel and alumina with 3% H₂O and the extracts were eluted with hexane and dichloromethane (1:1). Additional clean-up was performed by using C18 SPE cartridges using acetonitrile as the eluting solvent. The samples were spiked with labelled internal standards for identification and quantification. Analysis of the analytes was performed using a high resolution gas chromatograph coupled to a high resolution mass spectrometer (GC–MS). 27 organochlorine pesticides and degradation products were detected. The concentrations of total DDT and total HCH ranged 300–152000 and 2–8300 mg/kg dry weight (dw), respectively. The concentrations for other compounds were up to 1400 mg/kg dw. The results indicated old contamination by technical mixtures and lack of significant degradation. It is recommended that clean-up and proper disposal of contaminated soil should be carried out.