Screening of Polychlorinated Biphenyls in Water Samples by Strategic Sample Composition-Solid Phase Extraction and Gas Chromatography Tandem Mass Spectrometry. Comparison of Different Strategies for Sample Composition

Abstract

Strategic Sample Composition (SSC) is a new sample composition technique that allows the reduction of the number of analytical determinations to be carried out in screening campaigns down to the very number of the original sample specimens while providing information particularised to the original sample specimens instead of average information. The application of this technique in environmental screening studies is shown. Technical mixtures of polychlorinated biphenyls (Aroclors) have been chosen as model contaminants in water samples to show the usefulness and potential of the SSC technique in this field. EPA 1668/1668a protocols were used for sample treatment. Gas chromatography hyphenated to tandem mass spectrometry was used for the analysis of the samples. Two types of sample composition design matrices (a conventional Plackett-Burman screening matrix and a supersaturated matrix) were used and compared in the study. A total of 22 sample specimens were considered. Four of these sample specimens were contaminated at levels between 200 and 750 ng/L (total PCB concentration). A total of 24 experiments are needed to process these 22 sample specimens when applying the conventional Plackett-Burman matrix. Comparatively, only 13 analytical determinations are needed when using the supersaturated matrix. Both types of matrices allow clear identification of the contaminated sample specimens and produced satisfactory estimations of their concentration levels. Special emphasis has been put in investigating and demonstrating the robustness of the SSC technique.