Title: Determination of Short-Chain Chlorinated Paraffins by Carbon Skeleton Gas Chromatography
Citation: Organohalogen Compounds vol. 70 p. 000776-000780
Publisher: International Dioxin Symposium Website
Publication Year: 2008
JRC N°: JRC45010
URI: http://www.dioxin20xx.org/pdfs/2008/08-140.pdf
Type: Articles in periodicals and books
Abstract: Short-Chain Chlorinated Paraffins (SCCPs) are highly complex technical mixtures of polychlorinated n-alkanes with a chlorination degree between 50 and 70 % by mass, and a linear carbon chain length from C10 to C13, constituted by thousands of homologues, diastereomers and enantiomers. They have been used in many different applications, such as extreme pressure additives in lubricants and cutting fluids, plasticizers in PVC, and flame retardants in paints, adhesives and sealants. SCCPs are toxic towards aquatic organisms, bioaccumulative and persistent, and therefore the concern about this class of pollutants has increased in the last few years. In 2000 the European Union has included SCCPs in the list of priority substances in the field of water policy, amending the Water Framework Directive (WFD) 2000/60/EC. The implementation of the directive requires that laboratories should be able to measure such substances reliably at the level of the environmental quality standard (EQS). Unfortunately, this is not the case for SCCPs. The analytical tools currently available for the analysis of this class of compounds are scarce and no methodology has been fully validated. This is due to the complexity of their mixtures, and the lack of pure solutions for calibrations as well as matrix-matched reference materials. No routine method for monitoring purposes exists and a poor comparability of results was demonstrated. At present determination of SCCPs is mostly performed by mass spectrometry (MS) in the Electron Capture Negative Ionisation (ECNI) mode. The quantification relies on the monitoring of [M-Cl]- ions of specific mass to charge (m/z) ratio for each SCCP group according to the method developed by Tomy et al. This approach is prone to interferences from other chlorinated compounds and from medium chain chlorinated paraffins, therefore a thorough clean-up of the sample and a careful selection of the ions to be detected are necessary. The method is also affected by a strong dependence on the degree of chlorination of the standard used for calibration. Errors of up to 1100 % have been reported when the calibrant does not match the chlorination degree of the sample. An alternative approach for SCCPs determination is the carbon skeleton gas chromatography (GC)-MS in which chlorinated paraffins are catalytic hydrodechlorinated to the corresponding n-alkanes (see Figure 1). Information on the chlorination degree is lost, but accurate quantification is possible. In this paper the two approaches are compared, and some preliminary results in the determination of SCCPs in water samples with the carbon skeleton method are presented.
JRC Directorate:Health, Consumers and Reference Materials

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