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Determination of Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) in Cosmetics — Gas Chromatography
1 Scope
This document specifies the principle, reagents and materials, apparatus, procedures, calculation of results, recovery rate and precision, and tolerance for the determination of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in cosmetics by gas chromatography.
This document is applicable to the determination of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in aqueous solution, emulsion and cream (except waxy based cosmetics) in resident and rinsing cosmetics.
2 Normative References
No normative reference is listed in this document.
3 Terms and Definitions
No terms and definitions are listed in this document.
4 Principle
The sample can be dispersed by isopropanol and extracted by n-hexane, then determined by gas chromatograph for qualitative retention time and quantitative by external standard method, and confirmed by gas chromatography-mass spectrometry if necessary.
5 Reagents and Materials
Unless otherwise specified, only chromatographically pure reagents are used.
5.1 Isopropanol
5.2 n-Hexane.
5.3 Standard substance: purity ≥ 95%. Information on octmethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) is given in Annex A.
5.4 Standard stock solution, 1000 μg/mL: take a proper amount of (to the nearest 0.0001 g) octmethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) standard substance (5.3) in a volumetric flask, and mix with n-hexane (5.2) in constant volume.
5.5 Mixed standard working solution: a proper amount of standard stock solution (5.4) shall be transferred to a volumetric flask and diluted with n-hexane (5.2) step by step to a mixed standard working solution with mass concentrations of 0.5 μg/mL, 1.0 μg/mL, 5.0 μg/mL, 20.0 μg/mL, 50.0 μg/mL and 100.0 μg/mL.
5.6 Organic filter membrane: with a pore diameter of 0.22 μm.
Contents
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents and Materials
6 Apparatus
7 Procedures
8 Calculation of Results
9 Recovery Rate and Precision
10 Tolerance
Annex A (Informative) Information on Standard Substances
Annex B (Informative) Gas Chromatograms of Standard Substances Octmethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5)
Annex C (Informative) Confirmatory Test
