ISO 8754:2025

Overview

ISO 8754:2025 - "Petroleum products - Determination of sulfur content - Energy-dispersive X-ray fluorescence spectrometry" specifies an EDXRF test method for measuring sulfur in a wide range of petroleum products and components. The method covers naphthas, unleaded motor gasolines, middle distillates, residual fuel oils, base lubricating oils and components, and is applicable to biofuel or biofuel blends. It applies to sulfur mass fractions from 0.03 % to 5.00 %. The standard replaces the 2003 edition and includes updates for matrix corrections and terms.

Key topics and technical requirements

• Analytical technique: Energy-dispersive X‑ray fluorescence spectrometry (EDXRF) - excitation from an X‑ray tube or radioactive source; measurement of sulfur Kα radiation and conversion of counts to mass fraction by calibration.
• Instrument essentials:
  • X‑ray excitation with significant flux above 2.5 keV
  • Removable sample cup with at least 3 mm sample depth and X‑ray transparent window film
  • Detector sensitive at around 2.3 keV
  • Filters or discrimination for sulfur Kα, pulse counting and pulse‑height analysis electronics
• Reagents and standards:
  • Low‑sulfur white oil diluent (preferably <2 mg/kg S) for calibration
  • Primary sulfur compounds (dibenzothiophene, dibutylsulfide, thionaphthene) or certified reference materials (supplier conforming to ISO 17034)
• Calibration & checks:
  • Preparation of primary and calibration standards; storage and routine short‑term/long‑term checking procedures
  • Matrix/multiple‑element interferences corrected by spectral deconvolution and inter‑element regression
• Interferences & matrix effects:
  • Heavy metal additives and elements (Si, P, Ca, K, Zn, Mo, Ba, halogens) can interfere at high concentrations
  • C/H (carbon/hydrogen) ratio and oxygen content (notably for biofuels) require matrix corrections (see Annex A)
• Sampling & precision:
  • Sampling per ISO 3170 / ISO 3171
  • Precision statements include repeatability (r) and reproducibility (R); biofuel blends included in scope though not covered in original precision testing
• Safety: Warning about hazardous materials, equipment and the responsibility of the user to apply safety practices.

Applications and users

• Routine quality control in refineries, fuel blending plants, and lubricant manufacturers
• Analytical laboratories performing regulatory compliance testing for sulfur limits in fuels and fuel blends
• Environmental monitoring groups and fuel certification bodies assessing sulfur-related emissions risk
• Developers of calibration materials and instrument manufacturers validating EDXRF performance

Related standards

• ISO 3170, ISO 3171 - sampling of hydrocarbon liquids
• ISO 13032 - specialized procedure for automotive fuels < 0.20 % S
• ISO 17034 - requirements for providers of certified reference materials

Keywords: ISO 8754:2025, sulfur content determination, EDXRF, petroleum products, biofuel blends, calibration, matrix effects, sulfur Kα, certified reference materials.