Overview
ISO/TS 22491:2019 specifies a laboratory method for the determination of carbon monoxide (CO) in the vapour phase of water pipe tobacco smoke using a non-dispersive infrared (NDIR) analyser. The Technical Specification defines sampling, instrumentation, calibration and calculation procedures so results can be expressed as CO volume and mass per water pipe tobacco test portion.
Key topics and technical requirements
- Scope and principle: Collection of the vapour phase during machine-smoked water pipe tobacco and measurement of CO by an NDIR analyser calibrated for CO.
- Apparatus: Requires a water pipe smoking machine compliant with ISO 22486, a vapour-phase collection system (bags or split-flow), an NDIR CO analyser and environmental instruments (barometer, thermometer).
- NDIR analyser performance:
- Sampling rate: 0.5–5 L/min
- Precision: 0.1% CO, linearity 0.1% CO, repeatability 0.2% CO
- Low cross-response to 10% CO and 2% water vapour (responses ≤ 0.05% as CO)
- Vapour-phase collection:
- Single large bags (practical volume 120–185 L for 175 puffs) or alternatives:
- Multiple smaller bags (~30 L) changed periodically
- Constant-flow split (example 20:1 ratio using a 10 L bag)
- Puff-by-puff collection and summation
- Impermeability and leakage checks specified (CO loss ≤ 0.2% volume fraction over ≥2 h).
- Calibration and gases:
- Use high-purity nitrogen as make-up gas; calibrate with at least three standard gas mixtures across the analyser range (relative error ≤ 2%).
- Recalibration schedule: at least weekly and verification before measurements.
- Procedure and calculations:
- Conditioning: tobacco conditioned ≥12 h at 22 °C ±3 °C (ISO 3402 ambient).
- Smoking follows ISO/TS 22487.
- Standard formulas provided to calculate CO volume and mass per test portion (uses standard puff volume 530 mL, standard pressure 101.3 kPa, triple point 273 K).
Applications and users
ISO/TS 22491:2019 is intended for:
- Regulatory and public health laboratories measuring CO emissions from water pipe tobacco
- Tobacco product testing labs and manufacturers performing product characterization and quality control
- Researchers studying exposure, toxicology and comparative emissions from smoking products
Benefits include reproducible CO emission data, traceable calibration practices and interoperability with related standard smoking-machine methods.
Related standards
- ISO 22486 - Water pipe tobacco smoking machine (definitions and standard conditions)
- ISO/TS 22487 - Determination of total collected matter and nicotine for water pipe tobacco
- ISO 3402 - Atmosphere for conditioning and testing
Keywords: ISO/TS 22491:2019, water pipe tobacco, carbon monoxide, NDIR method, vapour phase, smoking machine, calibration, CO measurement.