Investigations on the substitution of dichloromethane in pesticide residue analysis of plant materials

Abstract

According to the multiresidue analysis method DFG S 19, different approaches for the substitution of dichloromethane in the liquid/liquid partition step were investigated. Due to maximum residue limits (MRL), fortification experiments with 17 GC/ECD and GC/NPD detectable pesticides were carried out in concentrations of 1 and 0.1 mg/kg apples, 1 and 0.05 mg/kg tomatoes, 1 and 0.1 mg/kg lettuce, respectively. In supplementary greenhouse experiments, lettuce was cultivated and a mixture of 10 plant protection products was applied in commonly used amounts. In both cases, the comparison of pesticide recoveries shows that several less toxic solvents like cyclohexane, light petroleum and tertiary butyl methyl ether are suitable substitutes for the more toxic and persistent dichloromethane.