The method is suitable for the determination of a wide range of different isocyanates in both the gas and particle phases. Typical monofunctional isocyanates that can be determined are isocyanic acid (ICA), methyl isocyanate (MIC), ethyl isocyanate (EIC), propyl isocyanate (PIC), butyl isocyanate (BIC), and phenyl isocyanate (PhI). Typical monomeric diisocyanates include 1,6-hexamethylene diisocyanate (HDI), 2,4- and 2,6-toluene diisocyanate (TDI), 4,4'-methylenediphenyl diisocyanate (MDI), 1,5-naphthyl diisocyanate (NDI), isophorone diisocyanate (IPDI), and 4,4'-dicyclohexylmethane diisocyanate (HMDI). Multifunctional isocyanates that can be determined are typically oligomers in polymeric MDI, biuret-, isocyanurate-, and allophanate-adducts, and prepolymeric forms of isocyanates.
The instrumental detection limit for aliphatic isocyanates is about 5 nmol/sample and for aromatic isocyanates, it is about 0,2 nmol/sample. For a 15 l air sample, this corresponds to 0,6 ng∙m?3 for HDI and 0,02 ng∙m?3 for TDI.
The useful range, for a 5 l air sample, of the method is approximately 0,001 µg∙m?3 to 200 mg∙m?3 for TDI.