Overview
ISO 9487:1991 - Workplace air: Determination of vaporous aromatic hydrocarbons specifies a validated laboratory method for measuring airborne vaporous aromatic hydrocarbons using a charcoal tube / solvent desorption / gas chromatographic procedure. The method is applicable for time‑weighted‑average concentrations roughly from 1 mg/m³ to 1 000 mg/m³ (when sampling 10 litres of air). Annexes A, B and C are integral; Annex D is informative.
Key phrases: ISO 9487:1991, workplace air, vaporous aromatic hydrocarbons, charcoal tube, solvent desorption, gas chromatographic method.
Key topics and technical requirements
- Target compounds: benzene, toluene, ethylbenzene, m‑/o‑/p‑xylene, styrene, cumene, trimethylbenzenes, and several other substituted monocyclic aromatics listed in the standard.
- Sampling medium: glass charcoal tubes (70 mm × 6 mm o.d., 4 mm i.d.) packed with activated coconut‑shell charcoal (particle size 0.4–0.8 mm). Typical packing: 100 mg front (adsorbing) + 50 mg backup.
- Desorption solvent: carbon disulfide (CS2) (chromatographic quality) is specified for desorbing collected vapours; safety precautions are required due to toxicity and flammability.
- Analysis: gas chromatograph with flame ionization detector (GC‑FID) or equivalent detector. Calibration via gravimetrically prepared standard solutions; desorption efficiency must be checked (annex B).
- Breakthrough and sampling limits: the useful upper range is limited by the adsorptive capacity (breakthrough volume) of the front charcoal section. Breakthrough testing and selection of sample volume/flow rate are essential (see Annex A and Tables provided).
- Equipment & QA: personal sampling pumps with stable low flow rates, soap‑bubble or equivalent flowmeter calibration, tube pre‑treatment (e.g., charcoal heated in inert atmosphere), sample blanks, storage (freeze or dry ice if analysis delayed >8 h).
- Validation notes: method validated for a selection of typical aromatic hydrocarbons. Interferences with co‑eluting organics must be managed by column selection and chromatographic conditions (guidance in Annex C).
Applications and users
- Who uses it: occupational hygienists, industrial safety officers, environmental testing laboratories, regulatory compliance personnel, and researchers assessing workplace exposure to aromatic solvents.
- Practical uses:
- Personal and fixed‑location sampling for 8‑hour time‑weighted‑average exposure assessments.
- Compliance monitoring against occupational exposure limits for benzene, toluene, xylene, styrene, etc.
- Baseline surveys and exposure trend analysis in manufacturing, painting, petrochemical and solvent‑using operations.
Related standards
- ISO 5725 (precision), ISO 6145‑1 and ISO 6349 (calibration gas preparation) are referenced for related quality and calibration practices.
This standard is essential for reliable workplace air monitoring of volatile aromatic solvents using established charcoal tube/solvent desorption/GC methods.
