Rapid and reversible adsorption of BTX on mesoporous silica thin films for their real time spectrophotometric detection in air at ppm levels.

Benzene, toluene and xylenes (BTX) are among the most toxic volatile organic compounds that can be emitted into the environment of different workplaces. Regulations to protect workers continue to strengthen permissible exposure limit (PEL), and short-term exposure limit (STEL) for any 15-min period are defined for BTX that should be controlled with rapid, selective and sensitive on-site sensors. For that purpose, a real-time analysis of BTX is described here, using the UV spectrometric determination of instantaneously concentrated pollutants in a thin film of mesoporous and transparent silica deposited onto quartz plates.