ISO 17196:2014

Overview

ISO 17196:2014 - "Dimethyl ether (DME) for fuels - Determination of impurities - Gas chromatographic method" defines a gas‑chromatographic procedure to quantify common impurities in DME used as a fuel. The method covers methanol, carbon monoxide (CO), carbon dioxide (CO2), methyl formate, ethyl methyl ether, and hydrocarbons up to C4. Results are reported as concentrations (volume % converted to mass %) and intended to support quality specification of DME in accordance with ISO 16861.

Key technical topics and requirements

• Analytes: methanol, CO, CO2, methyl formate, ethyl methyl ether, and C1–C4 hydrocarbons (ethane, ethylene, propane, propylene, butanes, butenes, 1,3‑butadiene).
• Analytical principle: separation by gas chromatography (packed or capillary columns) with detection by TCD, FID, or FID with methanizer where appropriate.
• Sample introduction: gas‑phase injection preferred (with complete vaporization) or liquid injection using a pressurized liquid valve. Heated transfer lines and vaporisers recommended to avoid condensation and sorption.
• Calibration and standards: use a Working Reference Mixture (WRM) and a control gas for routine calibration and control charts. WRM concentrations should lie within specified tolerances relative to ISO 16861 (e.g., ±50% for components ≤0.1 mass %; ±25% for 0.1–1 mass %).
• Chromatographic performance: minimum resolution of 2 between adjacent peaks (and ≥4 when valve switching is used).
• Calculations: concentration derived from peak areas against WRM (volume %), then converted to mass % using molecular masses.
• Precision: repeatability and reproducibility were evaluated in limited interlaboratory tests; because the study set and number of labs were limited, the method supports quality specification but is not claimed as a fully validated precision method per ISO 4259/5725‑2.

Practical applications and users

• Fuel producers and distributors: routine quality control of DME batches to confirm impurity limits required by fuel specifications (ISO 16861).
• Analytical laboratories: method for accredited testing of DME impurities using GC systems (TCD/FID/methanizer).
• Regulatory bodies and purchasers: verifying compliance of supplied DME with impurity specifications.
• Engine and fuel system developers: assessing feedstock purity for combustion performance and emissions testing.

Practical considerations include proper sampling per ISO 29945, heated transfer lines to avoid fractionation of volatile components (CO/CO2), and preparation/verification of calibration gas mixtures (ISO 6142/6143).

Related standards

• ISO 16861 - DME fuel specifications
• ISO 29945 - Sampling of refrigerated DME
• ISO 6142 / ISO 6143 - Preparation and verification of calibration gas mixtures
• ISO 6975 - Gas‑chromatographic vocabulary and methods
• ISO 5725‑2 and ISO 4259 - Precision and application of precision data

Keywords: ISO 17196:2014, Dimethyl ether, DME, gas chromatography, impurities, methanol, CO, CO2, methyl formate, ethyl methyl ether, hydrocarbons up to C4, fuel quality, WRM, calibration, precision.