本文件规定了一种测定环境水样中某些环状挥发性甲基硅氧烷（cVMS）的方法，该方法以低密度聚乙烯（LDPE）作为防腐剂，然后用含有13C标记的cVMS的己烷作为内标物进行液-液萃取。然后通过气相色谱-质谱(GC-MS)分析提取物。 注:使用13C标记的化学性质相同的物质作为与相应分析物具有相同性质的内标，可最大限度地减少校准中可能的物质特异性区分。由于这些物质最不溶于水，因此通过萃取溶剂己烷将它们引入系统中。

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.