This document specifies a method for the determination of the concentration hydrochloric acid (HCl) and hydrofluoric acid (HF) in biomethane, after absorption on an alkali-impregnated quartz fiber filter or in a sorbent trap, by ion chromatography (IC) with conductimetric detection. The method is applicable to biomethane for concentration levelsfor HCl from 0,07 mg/m3 to 35 mg/m3; and for HF from 0,07 mg/m3 to 20 mg/m3. Unless stated otherwise, all concentrations in this standard are given under standard reference conditions (see ISO 13443[3]). Other conditions may be applied. This method is also applicable to biogas. This method is intended to support conformity assessment of biomethane and biogas according to specifications, such as EN 16723[1][2].