Development of a personal isocyanate sampler based on DBA derivatization on solid-phase microextraction fibers

The design and evaluation of a portable diffusive sampler for isocyanates is described. The sampler employs dibutylamine (DBA) loaded onto 60-mum polydimethylsiloxane-divinylbenzene (PDMS-DVB) solid-phase microextraction (SPME) fibers. The DBA-isocyanate derivative is then desorbed by sonication and analyzed by LC-MS using atmospheric pressure chemical ionization (APCI). The samplers are calibrated (i.e. the uptake rate is calculated) by exposing them to a known concentration of hexamethylene diisocyanate (HDI) in a standard gas-generation chamber. The uptake rate for the proposed method, at room temperature (25 degreesC), is 1.13 pg (min ppb(v))(-1) and the method detection limit is 3.2 mug m(-3), equivalent to less than 10% of the airborne time-weighted average (TWA) exposure limits recommended by both the National Institute for Occupational Safety and Health (NIOSH) and the American Conference of Governmental Industrial Hygienists (ACGIH). Practical points that should be considered when using the SPME device as a diffusive sampler are discussed.