Overview
ISO 15597:2025 specifies a laboratory method for the determination of chlorine and bromine content in liquid petroleum products, synthetic oils and fluids, and petroleum additives (including used oils) using wavelength-dispersive X‑ray fluorescence (WDXRF). The standard covers sample preparation, calibration, instrumentation requirements and calculation/reporting procedures for chlorine mass fractions from 0.0005 % to 0.1000 % and bromine mass fractions from 0.0010 % to 0.1000 %. It is the second edition and updates the original 2001 version.
Key topics and technical requirements
- Principle: Measurement of Cl and Br X‑ray fluorescence intensities (specific X‑ray lines) with a bismuth solution used as an internal standard; net count‑rate ratios are converted to concentrations using calibration curves.
- Scope & sample types: Liquid petroleum products, synthetic oils/fluids and additives soluble in organic solvents with negligible or known Cl/Br content; includes used oils with noted limitations.
- Limits of detection & interferences: Specified mass‑fraction ranges for Cl and Br. Lead can interfere above ~0.1500 %; used lubricants may raise practical detection limits.
- Reagents & standards: High‑purity white oil, oil‑soluble chlorine and bromine primary compounds (e.g., 1‑chlorooctane, 1,1,2,2‑tetrabromoethane), certified reference materials (ISO 17034), and triphenylbismuth plus 2‑ethylhexanoic acid as the internal standard solution.
- Instrumentation: Wavelength‑dispersive XRF spectrometer with appropriate anode (Rh, Sc, Cr or equivalent), analysing crystals (Germanium for Cl, LiF for Br), helium optical path, thin polymer cell windows (2–6 µm) and suitable detectors (proportional counter or scintillation for Br).
- Calibration & procedure: Preparation of stock/standard solutions, calibration curves, measurement protocols, calculation of mass fractions, precision characterization (repeatability and reproducibility) and test reporting.
- Sampling guidance: Follow ISO 3170 / ISO 3171 for manual or automatic sampling; sample homogenization and filtering requirements are given.
Applications - who uses it
- Quality control laboratories in petroleum refining, lubricant and additive manufacturing for verifying additive levels and contamination.
- Conformity and regulatory testing where Cl/Br content affects corrosion, emission or classification requirements.
- Used oil analysis and forensic investigations for contamination assessment (with care for interferences).
- Instrument manufacturers and method validators implementing WDXRF procedures and calibration routines.
Related standards
- ISO 3170, ISO 3171 (sampling of hydrocarbon liquids)
- ISO 17034 (certified reference material producers)
- ISO/IEC Directives (document development and editorial rules)
Keywords: ISO 15597:2025, WDXRF, wavelength-dispersive X-ray fluorescence, chlorine determination, bromine determination, petroleum products, bismuth internal standard, calibration solutions, used oils, quality control.
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