Detection tube with composite carrier for detection of phosgene and diphosgene in air

A new highly sensitive detection tube for measurement of concentration of phosgene and diphosgene in air has been developed. The detection is based on chemical reaction of 4-(p-nitrobenzyl)pyridine and N-phenylbenzylamine which with phosgene (diphosgene) give characteristic red methine dye. As a carrier serves spherical granules (pellets) of composite material prepared by granulation of microcrystalline cellulose with MgO. This new indication filling is stable, resistant to interferences and climatic influences. The detection limit (0.05 mg.m-3) meets the requirements for conducting hygienic checks of air quality in the workplace environment. In addition, the tube allows a prolonged and continuous monitoring of phosgene and diphosgene in air for at least 240 minutes.