Time-resolved sampling of toluene diisocyanate-peak exposure and long-term monitoring field applications

A time-resolved (TR) sampler was demonstrated for field measurements of toluene diisocyanate (TDI) at a polyurethane (PU) slabstock plant. The sampler consisted of 11 individual tubes, impregnated with equimolar amounts of di-n-butyl amine (DBA) and acetic acid. During sampling, the active flow automatically switched sequentially between 10 of the sampler tubes, generating a TR air concentration profile. One of the 11 tubes was used to correct for the passive sampling of TDI. The collected TDI-DBA derivatives were analysed using LC-MS/MS. The TR sampler was used to monitor TDI peak exposure, using a 10-min total sampling time with a 1-min dwell time for each tube at a flow rate of 2.0 l/min. It was also tested for long-term sampling, with a total sampling time of 96 h, during which the individual tubes collected samples for 9 to 15 h at a flow rate of 0.2 or 0.5 l/min. The TR sampler showed a good correlation when compared to sampling with a reference sampler (ISO 17734-1:2013), both for short-term (10 min) and long-term (96 h) sampling. When used for short-term field measurements in the breathing zone of a worker, the TR sampler highlighted the significance of TR exposure data. The importance of accounting for peak exposures was clearly demonstrated, even during short sampling periods such as 10 min. Additionally, the TR sampler proved to be reliable for long-term TDI sampling, offering the ability to capture day-to-day exposure patterns for continuous, automated sampling over up to 10 d.