Workplace atmospheres — Determination of total isocyanate groups in air using 1-(9-anthracenylmethyl)piperazine (MAP) reagent and liquid chromatography

This document specifies a method for the sampling and analysis of airborne organic isocyanates in workplace air.

This document is applicable to a wide range of organic compounds containing isocyanate groups, including monofunctional isocyanates (e.g. phenyl isocyanate), diisocyanate monomers [e.g. 1,6-hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), and isophorone diisocyanate (IPDI)], prepolymers (e.g. the biuret and isocyanurate of HDI), as well as chromatographable intermediate products formed during production or thermal breakdown of polyurethane.

In mixed systems of HDI and IPDI products, it is impossible to identify and quantify low levels of IPDI monomer using this document, due to coelution of IPDI monomer with HDI-uretidinedione.

It is known that the method underestimates the oligomer in MDI-based products. Total isocyanate group (NCO) is underestimated in MDI-based products by about 35 % as compared to dibutylamine titration.

The method has been successfully modified to be used with LC-MS-MS for TDI monomer using an isocratic 70 % acetonitrile/30 % 10 mM ammonium formate mobile phase.

The useful range of the metho