An Approach to Area Sampling and Analysis for Total Isocyanates in Workplace Air

• Published in: American Industrial Hygiene Association journal Vol. 60; no. 2; pp. 200 - 207
• Main Authors: Key-Schwartz, Rosa J., Tucker, Samuel P.
• Format: Journal Article
• Language: English
• Published: Fairfax, VA AIHA JOURNAL 01.03.1999; American Industrial Hygiene Association; Taylor & Francis Ltd
• Subjects: Aerosols; Air Pollutants, Occupational - analysis; Analysis methods; Applied sciences; Atmospheric pollution; Calibration; Chemicals; Chromatography; Chromatography, High Pressure Liquid - methods; Dimethyl Sulfoxide; Environmental Monitoring - methods; Exact sciences and technology; Humans; Indoor air quality; Indoor pollution and occupational exposure; isocyanates; Isocyanates - analysis; Laboratories; Methods; Occupational Exposure - analysis; Occupational hazards; Occupational safety; Pollution; Reagents; Reproducibility of Results; sampling and analysis; Sampling techniques; Sensors; Solvents; Studies; Workplace; Fluorescence detector; Work place; Chemical analysis; Tryptamine; HPLC chromatography; Air quality; Air; Calibration; Derivatization; Methyl sulfoxide; Organic diisocyanate; Detection limit; Indoor pollution; Sampling; Performance; Organic compounds
• ISSN: 0002-8894; 2163-369X
• DOI: 10.1080/00028899908984436

An approach to sampling and analysis for total isocyanates (monomer plus any associated oligomers of a given isocyanate) in workplace air has been developed and evaluated. Based on a method developed by the Occupational Health Laboratory, Ontario Ministry of Labour, Ontario, Canada, isocyanates present in air are derivatized with a fluorescent reagent, tryptamine, in an impinger and subsequently analyzed via high-performance liquid chromatography (HPLC) with fluorescence detection. Excitation and emission wavelengths are set at 275 and 320 nm, respectively. A modification to the Ontario method was made in the replacement of the recommended impinger solvents (acetonitrile and 2,2,4-trimethylpentane) with dimethyl sulfoxide (DMSO). DMSO has the advantages of being compatible with reversed-phase HPLC and not evaporating during sampling, as do the more volatile solvents used in the Ontario method. DMSO also may dissolve aerosol particles more efficiently during sampling than relatively nonpolar solvents. Several formulations containing diisocyanate prepolymers have been tested with this method in the laboratory. This method has been issued as National Institute for Occupational Safety and Health (NIOSH) Method 5522 in the first supplement to the fourth edition of the NIOSH Manual of Analytical Methods. This method is recommended for area sampling only due to possible hazards from contact with DMSO solutions containing isocyanate derivatives. The limits of detection are 0.1 µg/sample for 2,4-toluene diisocyanate, 0.2 µg/sample for 2,6-toluene diisocyanate, 0.3 µg/sample for methylene bisphenyl diisocyanate, and 0.2 µg/sample for 1,6-hexamethylene diisocyanate.