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.st edition 2021-01 Water quality — Determination of cyclic volatile methylsiloxanes in water — Part 2: Method using liquid-liquid extraction with gas chromatography-mass spectrometry (GC-MS) Qualité de l'eau — Détermination de méthylsiloxanes cycliques volatiles dans l'eau — Partie 2: Méthode par extraction liquide-liquide avec chromatographie en phase gazeuse-spectrométrie de masse (CG-SM) Reference number ISO 20596-2:2021(E) ？ ISO 標(biāo)準(zhǔn)截圖