Rapid Analysis of Low Molecular Weight Cyclic Siloxanes Using a Backflush GC System

Introduction

Silicone features many useful characteristics such as excellent heat resistance, chemical resistance and low toxicity, and is widely used in electrical and electronic devices. The silicone used in such products often contains cyclic siloxanes with low molecular weight, which may become a cause of conduction faults. Cyclic siloxanes are compounds comprising three or more linked siloxane units and indicated as Dn with the "n" indicating the number of linked units. In many cases, the term low molecular weight cyclic siloxane refers to compounds with 3 (D3) to 10 (D10) linked siloxane units, and the total weight of such siloxanes from D3 to D10 is used as an index for quality standards. Gas chromatography (GC) is frequently used to analyze low molecular weight cyclic siloxanes. However, the method has its drawbacks. Extracts from silicone products contain many components with high boiling points and the removal of such components from the column requires heating at a high temperature over a long period of time, which in turn elongates the analysis time. Furthermore, if the removal of components with high boiling points is insufficient, residues may be detected in the subsequent analysis. This article introduces a backflush GC system which enables rapid analysis of low molecular weight cyclic siloxanes.

June 15, 2023 GMT