Standards Development

Scope

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 the internal standard substances 13C-labeled cVMS1).

The extract is then analysed by gas chromatography-mass spectrometry (GC-MS).

This document is applicable to the measurement of the following cVMS in rivers, streams, and waste water (influent and effluent):

Analytes determined by this method

Analyte Formula Abbreviation CASa -RN Octamethylcyclotetra siloxane C8H24O4Si4 D4 556-67-2

Decamethylcyclopent asiloxane C10H30O5Si5 D5 541-02-6

Dodecamethylcycloh exasiloxane C12H36O6Si6 D6 540-97-6

a CAS-RN Chemical Abstracts Services Registration Number

This method can be used to determine cVMS from 0,1 μg/l to 250 μg/l. In very controlled laboratory environments, extremely minimizing contamination, the lower end of the application range can be diminished by a factor of up to 10.

Purpose

Volatile methylsiloxanes are found in personal care products (PCP), cosmetics, and industrial fluids. They are high production volume chemicals. Of particular note is the use in PCP where approximately 90 % of the used cVMS volatilize during use and the remainder is discharged into wastewater streams. Upon reaching a wastewater treatment plant (WWTP), the majority of cVMS partitions to air and sludge, while only 1 % to 2 % partitions to water. This discharge of cVMS into waterways has caused an interest by regulatory bodies, and studies have been reported investigating the environmental exposure effects and risk assessments.