1 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 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 is applicable to the measurement of the following cVMS in rivers, streams,
and waste water (influent and effluent):
Table 1
—
Analytes determined by this method
|
Analyte
|
Formula
|
Abbreviation
|
CAS
a
-RN
|
| Octamethylcyclotetrasiloxane |
C8H24O4Si4
|
D4 |
556-67-2 |
| Decamethylcyclopentasiloxane |
C10H30O5Si5
|
D5 |
541-02-6 |
| Dodecamethylcyclohexasiloxane |
C12H36O6Si6
|
D6 |
540-97-6 |
This method can be used to determine cVMS from 0,1 µg/l to 250 μg/l. In well controlled
laboratory environments, where contamination is minimized, the lower end of the application
range can be diminished by a factor of up to 10.