scope:

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 bar¹⁾, temperatures of 0 °C - 40 °C and relative humidity < 90 %.

¹⁾ 1 bar = 0,1 MPa =10⁵ Pa; 1 MPa = 1 N/mm².