Application of a polysiloxane-based extraction method combined with large volume injection-gas chromatography-mass spectrometry of organic compounds in water samples

This work describes a novel, simple, and inexpensive approach for an absorptive extraction of organic contaminants from aqueous samples applying polysiloxane tubes. After the extraction, the tubes were desorbed with 200 μL of an organic solvent and 50 μL of the extract were transferred via large volume injection (LVI) into a gas chromatography-mass spectrometry system (GC-MS). Fourteen organic compounds covering a broad range in polarity with log Ko/w-values between 2.6 (atrazine) and 7 (polychlorinated biphenyl 138, PCB 138) were chosen as model compounds. The experimental parameters affecting the efficiency of the process such as desorption solvents, the addition of salt and pH-change, the extraction and desorption time were carefully optimised. The recoveries were compared with theoretical values. The limits of detection (LODs) were in the range of 0.5-5 ng/L and the precision was 7-15%. The method was successfully applied to the analysis of a contaminated river water sample.