Overview
ISO 2620:2024 specifies a standardized method for the sampling and analysis of volatile organic compounds (VOCs) in natural gas and biomethane. The method uses thermal desorption coupled with gas chromatography and flame ionization and/or mass spectrometry detectors (TD‑GC‑FID/MS). It covers VOC families commonly found in biogas and biomethane-such as siloxanes, terpenes, organic sulfur compounds, ketones, alkanes and furans-and supports traceable, fit‑for‑purpose testing for grid injection and transport fuel compliance.
Key topics and technical requirements
- Analytical principle: Adsorb VOCs on sorbent tubes, thermally desorb into a GC with capillary column, identify by MS (EI mode) and/or retention indices, quantify with FID and/or MS.
- Detectors & instrumentation: TD‑GC with capillary column; MS (electron ionization) and/or FID; recommended two‑stage thermal desorption with a cooling trap for focusing.
- Sorbent tubes: Use preconditioned tubes compatible with TD systems (typical ~200 mg sorbent); condition tubes at temperatures below adsorbent limits and 25 °C above intended desorption temp.
- Sampling: Collect accurately known gas volume using calibrated volumetric flow controllers (typical sampling flows 50–500 ml/min; typical sample times 1–4 min). Use short, passive tubing and field tube blanks to assess background contamination.
- Calibration and spiking: Use individual VOC standards of purity >99%. Prepare liquid spiking solutions (examples given at ~0.2, 0.04 and 0.01 mg/ml) and prepare standard tubes by liquid introduction and inert gas purging.
- Performance: Expected quantification limit is around 2–5 ng on tube (equivalent to ~20–50 μg/m3 for a 100 ml sample).
- Documentation & QA: Includes requirements for field blanks, sample records (flow, volume, location, temperature, pressure), and quality assurance procedures.
Applications and users
ISO 2620:2024 is intended for:
- Analytical laboratories performing VOC characterization of biomethane and natural gas
- Biomethane producers and biogas upgrading facilities monitoring residual VOCs
- Gas grid operators and regulators requiring conformity assessment for injection
- Transport fuel suppliers using biomethane as compressed or liquefied gas
- Product testing and R&D teams evaluating siloxanes, terpenes and sulfur compounds in renewable gases
Practical uses include compliance testing, process troubleshooting, impurity profiling before grid injection, and establishing metrological traceability for market trade.
Related standards
- ISO 14532 - Natural gas vocabulary (terms and definitions referenced)
- ISO 16000‑6:2021 - referenced for sorbent guidance and selection
Keywords: ISO 2620:2024, biomethane VOCs, TD‑GC‑FID/MS, thermal desorption, siloxanes, terpenes, organic sulfur compounds, sorbent tubes, natural gas analysis.
Open preview (PDF)Analysis of natural gas — Biomethane — Determination of VOCs by thermal desorption gas chromatography with flame ionization and/or mass spectrometry detectors
