ISO/TC 147/SC 2/WG 72 - Methylsiloxanes

This document specifies a method for the determination of certain cyclic volatile methylsiloxanes (cVMS) in environmental water samples with low density polyethylene (LDPE) as a preservative and subsequent liquid-liquid extraction with hexane containing 13C-labeled cVMS as internal standards. The extract is then analysed by gas chromatography-mass spectrometry (GC-MS). NOTE Using the 13C-labeled, chemically identical substances as internal standards with the same properties as the corresponding analytes, minimizes possible substance-specific discrimination in calibrations. Since these substances are least soluble in water, they are introduced via the extraction solvent hexane into the system.

This document specifies a method for the quantitative determination of selected cyclic volatile methylsiloxanes (cVMS) in non-filtered water samples by purge and trap extraction with isotope dilution gas chromatography-mass spectrometry (GC-MS). This method is applicable to the determination of individual cVMS, including: — octamethylcyclotetrasiloxane (D4); — decamethylcyclopentasiloxane (D5); — dodecamethylcyclohexasiloxane (D6); in surface water, ground water, and wastewater. It can be applied to samples within the concentration range of 0,01 µg/l to 1 µg/l of each of the target compounds. Depending on the matrix, the method may also be applicable to higher concentrations ranging from 1 µg/l to 100 µg/l after suitable dilution of the sample or reduction in sample size.