Epsilon Archive for Student Projects

Abstract

The aim of this study was to develop a sampling method for pesticide residues in water using solid-phase extraction. A sampling equipment has been assembled constituting of a raft, a filter holder with glass micro fibre filter, and an ENV + solid-phase column connected to a vacuum flask and a pump with reversed function. The equipment can easily be brought out in the field and sampling of a volume of 500-1000 ml can be carried out within 30 minutes. Water soluble and particle bound residues are separated. By using the solid-phase sampling equipment losses of analytes through degradation and adsorption can be reduced and transport of samples to the laboratory is facilitated. The dissolved fraction of a pesticide is captured in the solid-phase column and a pre-washing step of ENV + is generally needed before use but activation of the columns can be excluded. Elution with dichloromethane can be made directly without a soaking step. The particle bound fraction collected on the glass micro fibre filter is efficiently extracted when using Soxtec extraction with dichloromethane/acetone (1:1, v/v). In the beginning of the study focus was on two pyrethroids, esfenvalerate and deltamethrin, since these hydrophobic substances can be difficult to recover from the solid-phase column. When appropriate extraction conditions were achieved for the two pyrethroids 14 other pesticides of different character were introduced in the study to investigate whether the selected extraction methods gave satisfactory recoveries. Adequate results (total recovery between 70 and 130%) were achieved for the following pesticides: atrazine, deltamethrin, diflufenican, diuron, esfenvalerate, ethofumesate, hexazinon, isoproturon, lambda-cyhalotrin, metazachlor, pirirnicarb, propiconazole and simazine. The recovery of terbutylazine exceeded 130% while the recovery of fenpropimorph and metarnitron were lower than 70%. Esfenvalerate, deltamethrin and lambda-cyhalothrin were to a large extent recovered from particles while the major portion of other pesticides studied were retrieved from the water phase.