Analysis of natural gas — Silicon content of biomethane — Part 2: Determination of siloxane content by gas chromatography with ion mobility spectrometry

This document describes a gas chromatography – ion mobility spectroscopy (GC-IMS) method for the determination of the concentration of siloxanes in biomethane. The method is applicable to the following siloxanes:

— hexamethyldisiloxane (L2);

— octamethyltrisiloxane (L3);

— decamethyltetrasiloxane (L4);

— dodecamethylpentasiloxane (L5);

— hexamethylcyclotrisiloxane (D3);

— octamethylcyclotetrasiloxane (D4);

— decamethylcyclopentasiloxane (D5);

— dodecamethylcyclohexasiloxane (D6).

This document describes suitable calibration and measurement strategies to quantify siloxanes in (bio)methane around and above the 0,3 mg m-3 (14 μmol mol-1) level and applies to analyses within absolute pressure ranges of 1 bar – 2 bar, temperatures of 0 °C – 40 °C and relative humidity < 90 %.