Overview
ISO 23506:2021 - "Workplace air - Analysis of airborne water immiscible mineral oil droplets and vapor with Fourier‑Transform infrared spectroscopy (FTIR)" - defines a validated laboratory and sampling method to quantify mineral oil exposure in the inhalable fraction of workplace air. The standard covers combined collection of mineral oil droplets and vapours using a filter-plus-polymer resin sampler and analysis by FTIR in the 3 000–2 800 cm⁻¹ region. It specifies the concentration range (0.5 mg/m³ to 125 mg/m³), required equipment, sample preparation, calibration and evaluation procedures, and provides guidance on uncertainty and validation.
Key Topics and Requirements
- Scope and measurement range: Quantification of mineral oil vapours and droplets in the inhalable fraction from 0.5 mg/m³ to 125 mg/m³.
- Sampling principle: Air is drawn through a glass fibre filter (droplets) with a downstream polymer resin tube (vapours). The sampler system used in the document (GGP) enables simultaneous collection of droplets and vapours.
- Analytical technique: Extracted samples are analysed by FTIR (wavenumber 3 000–2 800 cm⁻¹) targeting C–H bond absorptions; the method detects all C–H containing substances, so it is not specific to mineral oil alone.
- Apparatus and reagents: Detailed requirements for collecting materials, sampler hardware, polymer resin preparation (drying, sieving, purification), solvents and glassware. Polymer purification steps include preparatory ethanol cleaning and tetrachloroethene treatment as given in the standard.
- Calibration and validation: Procedures for stock solutions, calibration standards (including liquid paraffin calibration), FTIR scanning parameters, instrument background, and sample measurement. The method has been validated (per EN 13936 and ISO 20581) with an expanded measurement uncertainty typically in the 20–30% range.
- Limitations / interferences: Method responds to any substances with C–H bonds collected on the sampler; droplets can vaporize and transfer to resin, so distinction between gas and droplet fractions can be limited.
Applications and Users
- Occupational hygienists and industrial hygiene laboratories measuring worker exposure to mineral oils in metalworking, machining, lubrication processes, and other industrial settings.
- Employers and HSE professionals implementing workplace monitoring programs and corrective controls for airborne oils.
- Regulatory bodies and consultants requiring a standardized, validated method for routine monitoring, exposure assessment, and compliance reporting.
- The method is applicable to water soluble oils and metal working fluids, as stated in the document.
Related Standards
Relevant referenced standards include ISO 1042, ISO 7708, ISO 13137, ISO 18158, ISO 20581 and EN 13936, which cover laboratory glassware, particle fraction definitions, pump requirements, terminology, general performance requirements, and procedure validation.
