Membrane-assisted solvent extraction of organochlorine compounds in combination with large-volume injection/gas chromatography-electron capture detection

Abstract

Membrane-Assisted solvent extraction is based on a small-scale liquid-liquid extraction with a polymer membrane (low-density polyethylene, LDPE) separating the aqueous from the organic phase. The organic analytes present in the aqueous sample dissolve in the membrane material and pass through it before being enriched in a small volume of organic solvent. As the organic extract is almost completely subjected to GC-ECD using large-volume injection, the volume of both aqueous sample and organic solvent can be minimised. The method was established using chlorobenzenes and HCHs as model compounds and extraction parameters were optimised. Detection limits, the linear dynamic range and reproducibility are shown. Membrane-assisted solvent extraction was applied to the analysis of heavily contaminated groundwater samples, and results were compared to conventional liquid-liquid extraction. The advantages of using a membrane between the two phases are that emulsion formation is prevented and macromolecular compounds and particles from the organic extract are excluded. This makes this extraction technique particularly suitable for complex samples high in organic matter.