ISO 19739:2004

Overview - ISO 19739:2004 (Natural gas, sulfur compounds, GC)

ISO 19739:2004 specifies procedures for the determination of sulfur compounds in natural gas using gas chromatography (GC). The standard covers analysis of hydrogen sulfide (H2S), carbonyl sulfide (COS), C1–C4 thiols, alkyl sulfides and tetrahydrothiophene (THT). It provides requirements for sampling, instrument setup, calibration, analysis and performance characteristics. Multiple GC-based methods are described in informative annexes so laboratories can select the most appropriate detector/column combination for their needs.

Key topics and technical requirements

• Scope of analysis: H2S, COS, mercaptans (thiols), sulfides and cyclic sulfides such as THT.
• Analytical principle: physical separation by GC and quantification by comparison with calibrated reference gases under identical measurement conditions.
• Sampling and handling: representative sampling per ISO 10715; attention to adsorption and reactive losses; purge times and heated transfer lines are recommended to avoid loss of low-level sulfur species.
• Temperature and storage: calibration and sample cylinders should be stored at temperatures above condensation points; if condensation occurred, allow horizontal storage and homogenization (example: 7 days) before use.
• Materials and cleanliness: use construction materials inert to sulfur compounds; inspect and clean cylinder connections to avoid contamination or loss.
• Columns and resolution: select stationary phases and column dimensions that achieve chromatographic resolution of at least 1.5 between adjacent peaks for reliable quantitation.
• Detectors and methods: annexes describe multiple detectors and GC configurations (fluorescence, sulfur-specific detectors, mass spectrometry, atomic emission, sulfur chemiluminescence, pulsed flame photometric detector options and column-switching strategies).
• Calibration and traceability: use primary/secondary/working reference gas mixtures and follow calibration procedures to ensure accuracy and comparability.
• Performance and reporting: specify repeatability/reproducibility, limits of detection, and required information in the test report.

Practical applications - who uses ISO 19739

• Natural gas producers and processors for quality control and odorant verification.
• Pipeline and transmission operators for safety monitoring and compliance.
• Analytical laboratories performing sulfur-speciation and trace sulfur analysis.
• Calibration gas manufacturers and instrument vendors validating GC methods.
• Regulators and inspection bodies assessing conformity with gas quality and safety requirements.

Related standards

• ISO 10715 - Natural gas sampling guidelines
• ISO 14532 - Natural gas vocabulary
• ISO 5725-2 - Measurement accuracy (repeatability/reproducibility)
• ISO 6141, ISO 6143, ISO 6145-10 - Calibration gas preparation and certification

ISO 19739:2004 is essential for reliable, traceable GC-based sulfur analysis in natural gas, helping laboratories choose appropriate methods and meet safety and quality requirements.