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Development of a new approach for total isocyanate determination using the reagent 9-anthracenylmethyl 1-piperazinecarboxylate.

Roh YM
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :56
Isocyanate compounds to which workers are exposed may include monomers, prepolymers, and/or other polymeric species generated during polyurethane production or thermal breakdown. Methods for the determination of isocyanate compounds in air typically involve derivatization of the isocyanate species with an amine reagent and analysis of the derivatized isocyanates by high-performance liquid chromatography (HPLC). These methods rely on a number of assumptions with regard to determining nonmonomeric isocyanate species. It must be assumed that peaks derived from isocyanate species can be recognized in the chromatogram and that the detector response factor of the unknown isocyanate species is the same as that of the derivatized monomer. It also must be assumed that all isocyanate species have eluted from the analytical column as observable peaks. Even when all these assumptions are reasonable, the task of identifying and quantifying numerous isocyanate peaks in a chromatogram requires much judgment on the part of the analyst and is labor intensive, making it difficult to process numerous samples in a routine manner. 9-Anthracenylmethyl1-piperazine carboxylate (PAC) is a newly developed derivatizing reagent designed to enable much simpler total isocyanate analysis. Like other amine reagents, it reacts rapidly with isocyanates to form stable derivatives, enabling HPLC analysis of monomers or other specific isocyanate species. However, PAC derivatives also undergo a cleavage reaction under mild, but selective, conditions to generate the same single analyte for all species. This has several advantages over conventional total isocyanate analysis: (1) Identification can be based on chromatographic retention time; (2) there is no compound-to-compound variability in response factor; (3) there is no concern about failure to elute all isocyanate species; and (4) quantification involves measurement of a single peak. Moreover, this technique may enable measurement of isocyanate groups chemically bound to particle surfaces, which cannot be measured by conventional chromatographic techniques.
Polymers; Polyurethane-foams; Monomers; Isocyanates; Thermal-decomposition; Reagents; Amines; Liquid-chromatography; Analytical-instruments; Analytical-processes; Sampling-methods; Laboratory-techniques; Measurement-equipment; Anthracenes; Azines; Methyl-compounds
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American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division