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

The use of tristimulus colorimetry for the determination of hydrogen cyanide in air by a modified König method

A simple visual and tristimulus colorimetric method (three-dimensional system CIE-L*a*b*) for the determination of trace amounts of hydrogen cyanide in air has been developed. The method is based on the suction of hydrogen cyanide through a chlorinating cartridge where cyanogen chloride is formed, which is further driven to an indicator disc made of a modified cotton fabric. This indicator disc is placed into an adapter. Prior to analysis, the disc is saturated with a chromogenic reagent, a solution of 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and 4-benzylpyridine in ethanol. In the presence of hydrogen cyanide (cyanogen chloride), a pink coloration emerges on the indicator disc, the intensity of which is evaluated either visually or by use of a tristimulus colorimeter. The detection limit is 0.1 mg m-3. The method is mainly suitable for mobile field analyses. It was applied for the CHP-5 chemical agent detector introduced into the equipment of the Czech Army corps

A simple in situ visual and tristimulus colorimetric method for the determination of diphosgene in air

A simple visual and tristimulus colorimetric method (three-dimensional system CIE–L*a*b*) for the determination of trace amounts of diphosgene in air has been developed. The method is based on the suction of diphosgene vapors through a modified cotton fabric filter fixed in a special adapter. Prior to analysis, the filter is saturated with a chromogenic reagent based on 4-(p-nitrobenzyl)pyridine. The optimal composition of the reagent is 2 g of 4-(p-nitrobenzyl)pyridine and 4 g of N-phenylbenzylamine in 100 ml of a 50:50 ethanol–glycerol mixture. The intensity of the formed red coloration of the filter is evaluated visually or by a tristimulus colorimeter (LMG 173, Lange, Germany). The detection limit is 0.01 mg m-3. Acetyl chloride and benzoyl chloride react in 150 and 50 times higher concentrations, respecttively. The method is suitable for mobile field analysis

A new detection tube to detect hydrogen cyanide in the air

A new simple and sensitive detection tube to detect hydrogen cyanide in the air has been developed. The detection tube is based on the reaction of hydrogen cyanide with 4-nitrobenzil to form a violet colored product. The reaction takes place on the carrier made of a composite material which was prepared by pelletization of a mixture of microcrystalline cellulose and MgO. The detection tube can detect hydrogen cyanide in the air in the range of concentrations 0.1-100 mg.m-3 based on visual evaluation (by naked eye) of the change of indication layer coloring and comparison with etalon. The detection limit is 0.05 mg.m-3. The detection tube is highly selective and sufficiently stable during storage