Determination of free toluene diisocyanates in flexible polyurethane foams using negative chemical-ionization mass spectrometry

Abstract

A simple and sensitive method was developed for the determination and confirmation of trace amounts of toluene diisocyanate (TDI) residues in a polyurethane foam. Foam samples were extracted with methanol in a mini-Soxhlet apparatus after addition of deuteriated toluene-2,4-diyl dimethylcarbamate as an internal standard. The extracts were concentrated, derivatized with pentafluoropropionic anhydride at 70 °C and analysed by capillary column gas chromatography with use of selected-ion monitoring in the negative-ion chemical-ionization mode. The limit of detection was 10 ng g^–1 for a 1.0 g sample. The recovery was above 79% and reproducibility assessments indicated good accuracy and precision over the concentration range of 20–500 ng g^–1. The method was applied to the determination of free TDIs in fresh foam samples.