Overview
ISO 9486:1991 specifies a validated laboratory and field method for measuring vaporous chlorinated hydrocarbons in workplace air using a charcoal tube / solvent desorption / gas chromatography procedure. The method covers airborne vapour concentrations from approximately 1 mg/m³ to 1 000 mg/m³ (when sampling ~10 litres of air) and is suitable for personal and fixed-location time‑weighted‑average monitoring. Annexes A, B and C are integral; Annex D is informative.
Key search terms: ISO 9486:1991, workplace air monitoring, chlorinated hydrocarbons, charcoal tube sampling, solvent desorption, gas chromatography, occupational hygiene, vapour monitoring.
Key topics and technical requirements
- Analytes covered: includes dichloromethane, chloroform, carbon tetrachloride, 1,1‑dichloroethane, 1,2‑dichloroethane, various dichloro/ trichloro/ tetrachloroalkanes and chlorobenzenes listed in the standard.
- Sampling media: glass charcoal tubes (70 mm length, ~6 mm OD) with two sections - typically 100 mg adsorbent front and 50 mg back-up (coconut shell charcoal, particle size 0.4–0.8 mm). Larger tubes (e.g., 400 + 200 mg) recommended for some low-breakthrough compounds or long-term sampling.
- Charcoal preparation: activated charcoal pretreated (e.g., heated in inert atmosphere at 600 °C) and handled to avoid recontamination.
- Sampling equipment: wearable pump with stable flow (volume within ±10% and flow constant within ±5%) capable of typical low flow rates (recommended sampling rates in table; common range 10–200 ml/min, with short‑term sampling possible at up to 200 ml/min).
- Desorption & analysis: solvent desorption (commonly carbon disulfide) and analysis by gas chromatography (FID normally; ECD or other detectors recommended where selectivity/sensitivity require). Desorption efficiency must be checked; tubes with efficiency < 0.75 (75%) shall not be used.
- Quality control & limits: detector sensitivity example - able to detect ~5 ng trichloroethene with S/N ≥ 5. Breakthrough volumes are compound‑ and condition‑dependent (humidity, temperature, concentration) and must be verified (Annex A). Use blanks and storage precautions (freeze or dry ice if analysis >8 h).
- Safety notes: carbon disulfide is toxic and highly flammable; chloroform and carbon tetrachloride are suspect carcinogens - handle per local safety rules.
Applications and users
- Occupational hygienists and safety officers conducting personal exposure monitoring
- Industrial and environmental laboratories performing compliant vapor monitoring
- Employers and consultants assessing compliance with workplace exposure limits
- Manufacturers of sampling tubes, pumps and analytical GC services
- Regulatory bodies and auditors verifying measurement methods and quality control
Related standards & guidance
- Referenced ISO standards on precision and calibration (e.g., ISO 5725, ISO 6145) and Annex C for GC column guidance. Annexes A–C in ISO 9486 provide required validation, breakthrough and desorption procedures.
This standard provides a reproducible, widely accepted protocol for accurate measurement of chlorinated solvent vapours in occupational air using charcoal adsorption and GC analysis.
