Time-resolved sampling of isocyanate peak exposure—chamber validation of a prototype sampler

A prototype sampler for time-resolved monitoring of toluene diisocyanate (TDI) exposure peaks was developed. The sampler contained multiple sampling tubes arranged in a manifold equipped with an internal valve and a step motor, enabling automatic switching of the sampling flow between the tubes, allowing a sequence of up to 10 samples to be collected automatically. The inlet part of the sampling tubes contained a glass wool plug, impregnated with equimolar amounts of di-n-butyl amine (DBA) and acetic acid, to ensure efficient collection and derivatisation of the diisocyanates. The diisocyanate-DBA derivatives were analysed using liquid chromatography tandem mass spectrometry. A streamlined workup procedure was introduced, consisting of a single extraction step combined with the addition of a deuterium-labelled internal standard. The streamlined workup procedure was validated against a reference method (ISO 17734). The sampler tubes were validated by monitoring concentrations from a TDI standard atmosphere and through comparative measurements with a reference method. During short-term sampling ( 90% compared to the reference sampler.