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The present research project is aimed at providing an accurate low-dose benzene exposure assessment method, by validating diffusive monitoring techniques for benzene personal exposure measurements at workplaces where low benzene concentrations are expected. The experiments have been conducted following the EN 838:2010 standard in the range of 16 to 320 µg/m3 (0.005 to 0.1 ppm). The study is part of the Concawe project on “accurate low-dose benzene exposure assessment, dose-specific metabolism and potential early markers” aiming at developing a methodology to monitor benzene exposures at low levels in environments typical of the petroleum industry. Diffusive sampling offers a reliable alternative to pumped sampling methods, intrinsic safety in potentially explosive atmospheres, lightness and ease of use. The tested diffusive sampler is radiello™, two alternative configurations of the sampler can be used: RAD130, packed with activated charcoal, suitable for solvent desorption and analysis by HRGC-FID, and RAD145, packed with graphitised charcoal, suitable for thermal desorption and analysis by HRGC-MS. For both configurations the sampler performances have fulfilled all requisites of the EN 838:2010 standard, in particular: bias due to the selection of a non-ideal sorbent is lower than 10% (no significant back diffusion of benzene due to concentration change in the atmosphere); bias due to storage of samples for up to 2 months is lower than 10%; nominal uptake rate for benzene on RAD130 is 74.6 ml/min and on RAD145 is 32.3 ml/min; expanded uncertainty of the sampling and analytical method is 20.2% on RAD130 and 26.1% on RAD145.

The laser photolysis of three 2-chloro-4-6-diamino-1,3,5-triazines, namely simazine, atrazine and propazine, was investigated. The products formed were detected by time-of-flight mass spectromety. The results illustrate that the main process is fragmentation competing with cluster formation. The hydrogen bonding proposed for the crystal structure of diaminotriazines should be responsible for the gas-phase clusterization occurring by laser ablation.