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MDHS 25 revisited: part 2, modified sampling and analytical procedures applied to HDI-based isocyanates
John White1, Paul Johnson, Ian Pengelly
1Health and Safety Laboratory, Harpur Hill, Buxton, UK. jwhite55white@btinternet.com
The Annals of Occupational Hygiene
|December 28, 2011
Summary
Researchers improved methods for detecting organic isocyanates (NCO) in air. Liquid chromatography-mass spectrometry (LC/MS/MS) offers better sensitivity and identification than older methods, while solid-phase samplers provide a practical alternative for workplace monitoring.
Area of Science:
- Occupational Health and Safety
- Analytical Chemistry
- Environmental Monitoring
Background:
- The Health and Safety Executive (HSE) method MDHS 25/3 is the standard for determining total organic isocyanates (NCO) in air.
- Continuous research and development aim to update and improve existing analytical methods for workplace air quality.
Purpose of the Study:
- To evaluate liquid chromatography-mass spectrometry (LC/MS/MS) as an advanced alternative to current LC with electrochemical and ultraviolet/visible detection (LC/EC/UV) for NCO analysis.
- To assess solid-phase sampling techniques as replacements for the traditional impinger-filter combination in MDHS 25/3.
Main Methods:
- Development and application of an LC/MS/MS technique for NCO determination.
- Evaluation of two solid-phase samplers: the FIN-MP sampler (coated GF/B filter) and the Rudzinski sampler (MP-impregnated PUF with GF/A backup filter).
- Comparison of new methods against the established impinger-filter method using HDI-based NCO in laboratory and workplace simulations.
Main Results:
- The LC/MS/MS method demonstrated superior sensitivity and identification capabilities compared to the LC/EC/UV method, with enhanced ease of use.
- Both FIN-MP and Rudzinski solid-phase samplers showed acceptable performance for oligomeric hexamethylene diisocyanate (HDI) sampling at levels relevant to UK short-term exposure limits.
- The FIN-MP sampler was identified as the preferred solid-phase alternative due to practical considerations.
Conclusions:
- LC/MS/MS represents a significant advancement for the accurate and efficient analysis of organic isocyanates in air.
- Solid-phase sampling, particularly the FIN-MP sampler, offers a viable and practical alternative to traditional methods for workplace air monitoring of HDI.
- These advancements contribute to an updated version (MDHS 25/4) of the standard method for organic isocyanate determination.
