Overview
ISO 2614:2023 specifies a micro gas chromatography (µGC) method for measuring the content of five terpenes in biomethane: alpha‑pinene, beta‑pinene, para‑cymene, limonene and 3‑carene. The method supports both on‑line and offline analysis and is designed for individual terpene amount fractions from 1 µmol/mol up to and including 10 µmol/mol (with minor modifications applicable above 10 µmol/mol). The standard addresses sampling, instrument requirements, calibration and reporting to ensure consistent biomethane terpene analysis for safety and fuel specification purposes.
Key topics and requirements
- Analytes covered: α‑pinene, β‑pinene, p‑cymene, limonene, 3‑carene (information in Annex A).
- Analytical technique: micro gas chromatography with thermal conductivity detector (µGC‑TCD). Example column: non‑polar 100% PDMS capillary for terpene separation.
- Calibration: Use methane‑matrix calibration gas mixtures (1–10 µmol/mol) with relative expanded uncertainties below 5%. Purity of terpene standards must be checked per ISO 19229.
- Sensitivity & performance: Detector should detect limonene at 0.5 µmol/mol with S/N ≥ 3:1. Limits of quantification for each terpene shall be below 1 µmol/mol. Within‑lab repeatability <5% and reproducibility <10% have been demonstrated; expanded uncertainty <13% for concentrations >2 µmol/mol (k = 2).
- Sampling & handling: Follow ISO 10715 and ISO 16664 guidance - use passivated materials, minimize adsorption, prevent condensation (e.g., heated sample lines or staged pressure reduction), and sample into evacuated cylinders when applicable.
- Quantification & uncertainty: Quantify by comparison with calibration responses (ISO 6143) and evaluate measurement uncertainty covering sampling, calibration and analysis.
- Reporting: Test report must include method reference, sampling details, quantification limits, amount fractions, expanded uncertainty (k = 2), and any deviations.
Applications and users
ISO 2614:2023 is intended for practical use by:
- Biomethane producers and treatment facilities (quality control and specification compliance).
- Grid operators and gas distributors (monitoring odorant masking risk due to terpenes).
- Accredited analytical laboratories performing trace component analysis in natural gas/biomethane.
- Instrument manufacturers and system integrators developing µGC analyzers for on‑line gas monitoring.
- Regulators and certification bodies setting biomethane fuel specifications and safety requirements.
Keywords: ISO 2614:2023, biomethane terpene analysis, micro gas chromatography, µGC‑TCD, alpha‑pinene, beta‑pinene, limonene, gas sampling, calibration gases.
Related standards
- ISO 6143 - Gas analysis (comparison methods, calibration).
- ISO 10715 - Natural gas - Gas sampling.
- ISO 14532 - Natural gas - Vocabulary.
- ISO 16664 - Handling of calibration gases.
- ISO 19229 - Purity analysis and treatment of purity data.
- ISO/IEC Guide 98‑3 and relevant Eurachem guides for uncertainty and validation.
Open preview (PDF)Analysis of natural gas — Biomethane — Determination of terpenes' content by micro gas chromatography