Overview
ISO 17198:2014 specifies a standardized test method for determining total sulfur in dimethyl ether (DME) used as a fuel using the ultraviolet (UV) fluorescence technique. The standard defines the principle, required reagents and apparatus, procedures for calibration and measurement, and reporting. It applies to total sulfur levels up to those indicated in ISO 16861 and is intended for quality control and compliance testing of DME fuel.
Key topics and technical requirements
- Analytical principle: Direct injection of DME into a high-temperature combustion tube where sulfur is oxidized to SO2; SO2 is excited by UV light and quantified by its fluorescence signal.
- Apparatus essentials:
- Furnace and quartz combustion tube (oxidation zone at ~1 000–1 100 °C; single- or two-zone furnace options noted).
- UV fluorescence detector, vapour drier to remove combustion water, flow controllers, microsyringe (5–50 µL), and syringe drive.
- High-purity carrier gas (argon or helium, ≥99.998%) and oxygen (≥99.75%).
- Reagents and standards: Use solvent-free or low-sulfur solvents (n-hexane or toluene recommended); prepare sulfur stock (~1 000 mg/L) from high-purity sulfur compounds (e.g., dibutyl sulfide, dibenzothiophene) to make multi-point calibration standards.
- Calibration & measurement:
- Multi-point calibration (minimum four standards) and blank corrections; example concentration ranges provided.
- Quantitative direct injection with volume or mass measurement of injected aliquot; construct calibration curves from averaged, blank-corrected responses.
- Quality and verification: Use quality-control samples and routine verification; instrument warm-up (UV source) and leak checks are required.
- Limitations & precision:
- Method does not detect sulfur that is non-volatile under ambient test conditions.
- Precision has been studied on a limited sample set and cannot be considered a full statistical precision determination per ISO 4259.
Applications and users
- Fuel producers and refiners performing DME quality control and batch release testing.
- Accredited testing laboratories conducting total sulfur determination in gaseous/liquefied fuels.
- Regulatory agencies and certification bodies verifying compliance with sulfur limits (refer ISO 16861).
- Logistics, storage and transport operators needing to monitor sulfur to reduce SOx emissions and prevent corrosion in equipment.
Related standards
- ISO 16861 - Specifications for dimethyl ether (DME) fuels (sulfur limits reference).
- ISO 29945 - Manual sampling method for refrigerated DME terminals.
- ISO 4259 - Statistical methodology for precision statements (referenced for limitations).
Keywords: ISO 17198:2014, dimethyl ether (DME), sulfur determination, UV fluorescence method, total sulfur, fuel quality control, DME testing, calibration standards.
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