Investigation of a cylindrical chemosorptive denuder for sampling and phase separation of toluene diisocyanate aerosols

Abstract

A cylindrical chemosorptive denuder in series with a glass fibre filter has been evaluated for sampling toluene diisocyanate (TDI) aerosols. The sampler is designed for measuring personal exposure to diisocyanates. Several denuder coatings and derivatising reagents were investigated. Dimethylpolysiloxane (SE-30) and 5% phenyl dimethylpolysiloxane (SE-54) with either dibutylamine (DBA) or dipentylamine (DPeA) as derivatising reagents yielded the lowest vapour breakthrough (the amount (%) of the vapour that passes through the denuder), close to values predicted by theory. Immobilisation of the SE-30 denuder coating by in-situ cross-linking yielded comparable results. With an SE-30/DBA-coated denuder operating within an airflow range of 100-500 mL min(-1), the phase separation was shown to be consistent with theoretical predictions derived by use of the Gormley-Kennedy equation. This provides a means of calculating the vapour breakthrough and correcting experimentally obtained values with regard to vapour-particulate phase distribution, suggesting that the denuder can provide accurate phase-distribution measurements. The SE-30/DBA denuder can be used over a concentration range spanning nearly six orders of magnitude. Its capacity is sufficient to perform 15-min exposure measurements of a TDI aerosol with air concentrations as high as 1,700 microg m(-3), 40 times higher than the Swedish occupational exposure limit (OEL). At the other end of the range, the estimated limit of detection (LOD) was less than 2 ng m(-3) for both the vapour and the aerosol phases when LC-ESI-MS-MS was used for chemical analysis.

Determination of airborne isocyanates

“…In both arrangements, the denuder stationary phase was polydimethylsiloxane (SE-30), and quantitative analysis was achieved by either LC-MS-MS [181] or LC-MS [182]. This denuder/filter system has also been successfully applied to the determination of TDI aerosols [183].…”

Validation of a diffusive sampling method for airborne low-molecular isocyanates using 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole-impregnated filters and liquid chromatography–tandem mass spectrometry

“…The latter are especially suited in all those cases where short-term peak concentrations have to be monitored, which are known to be a substantial contributor to the development of occupational asthma. In order to be better suited for personal sampling, solvent free methods are gaining importance [47][48][49].…”