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Determination of technical grade isocyanates used in the production of polyurethane plastics
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
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2004 (English)In: Journal of Environmental Monitoring, Vol. 6, no 7, 606-614 p.Article in journal (Refereed) Published
Abstract [en]

A method for determination of technical grade isocyanates used in the production of polyurethane (PUR) is presented. The isocyanates in technical grade products were characterised as di-n-butylamine (DBA) derivatives using LC-MS and LC-chemiluminescent nitrogen detection (CLND) and the total isocyanate content was compared to a titration assay. For collection of isocyanates in air, an impinger–filter sampling technique with DBA as derivatisation reagent was used. Characterised DBA and nonadeuterium labelled DBA derivatives of isocyanates in technical products were used as calibration standards and internal standards, respectively, in the analysis of air samples. Three workplaces were studied where PUR products were produced either by spraying or by moulding. In both technical products and in air samples, a number of monomeric, oligomeric and prepolymeric isocyanates of e.g. methylenebisphenyl diisocyanate (MDI) and hexamethylene diisocyanate (HDI) were characterised. Several of these have not previously been described in workplace atmospheres. In the technical isocyanate products, between 69 and 102% of the NCO content determined by titration was accounted for by LC-CLND. Quantifications of a wide range of isocyanates in air samples were performed with correlation coefficients in the range 0.988–0.999 (n= 8) and the instrumental detection limits were 0.7–25 pg. At the two workplaces where MDI- and HDI isocyanurate-based products were sprayed, the isocyanate composition in the air reflected the composition in the technical product. At the workplace where a MDI-based product was used in a moulding process, only the monomeric isocyanates were found in the air. The advantage of using characterised technical grade isocyanates as analytical standards was clearly demonstrated and the possibility of using index compounds when monitoring isocyanate exposure is discussed.

Place, publisher, year, edition, pages
Royal Society of Chemistry , 2004. Vol. 6, no 7, 606-614 p.
URN: urn:nbn:se:su:diva-23247DOI: 10.1039/b402775bOAI: diva2:190904
Part of urn:nbn:se:su:diva-204Available from: 2004-08-20 Created: 2004-08-20 Last updated: 2010-01-05Bibliographically approved
In thesis
1. Isocyanates and Amines – Sampling and Analytical Procedures
Open this publication in new window or tab >>Isocyanates and Amines – Sampling and Analytical Procedures
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis covers sampling and analytical procedures for isocyanates (R-NCO) and amines (R-NH2), two kinds of chemicals frequently used in association with the polymeric material polyurethane (PUR). Exposure to isocyanates may result in respiratory disorders and dermal sensitisation, and they are one of the main causes of occupational asthma. Several of the aromatic diamines associated with PUR production are classified as suspected carcinogens. Hence, the presence of these chemicals in different exposure situations must be monitored.

In the context of determining isocyanates in air, the methodologies included derivatisation with the reagent di-n-butylamine (DBA) upon collection and subsequent determination using liquid chromatography (LC) and mass spectrometric detection (MS). A user-friendly solvent-free sampler for collection of airborne isocyanates was developed as an alternative to a more cumbersome impinger-filter sampling technique. The combination of the DBA reagent together with MS detection techniques revealed several new exposure situations for isocyanates, such as isocyanic acid during thermal degradation of PUR and urea-based resins. Further, a method for characterising isocyanates in technical products used in the production of PUR was developed. This enabled determination of isocyanates in air for which pure analytical standards are missing. Tandem MS (MS/MS) determination of isocyanates in air below 10-6 of the threshold limit values was achieved.

As for the determination of amines, the analytical methods included derivatisation into pentafluoropropionic amide or ethyl carbamate ester derivatives and subsequent MS analysis. Several amines in biological fluids, as markers of exposure for either the amines themselves or the corresponding isocyanates, were determined by LC-MS/MS at amol level. In aqueous extraction solutions of flexible PUR foam products, toluene diamine and related compounds were found.

In conclusion, this thesis demonstrates the usefulness of well characterised analytical procedures and techniques for determination of hazardous compounds. Without reliable and robust methodologies there is a risk that exposure levels will be underestimated or, even worse, that relevant compounds will be completely missed.

Place, publisher, year, edition, pages
Stockholm: Institutionen för analytisk kemi, 2004. 65 p.
Isocyanates, Amines, Polyurethane, Air sampling, Industrial hygiene, Mass spectrometry, Liquid chromatography, Chemiluminescence
National Category
Analytical Chemistry
urn:nbn:se:su:diva-204 (URN)91-7265-917-3 (ISBN)
Public defence
2004-09-10, Vita salongen, Hässleholms kulturhus, Järnvägsgatan 23, Hässleholm, 10:00
Available from: 2004-08-20 Created: 2004-08-20Bibliographically approved

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