METHOD OF INDICATION AND QUANTITATIVE DETERMINATION OF AMMONIA VAPORS IN AIR Russian patent published in 1998 - IPC

FIELD: analytical methods. SUBSTANCE: air is passed through silica gel treated by 0.01 N hydrochloric acid solution and then in series with 0.1 M sodium hypobromite in 5% sodium or potassium alkali and 0.5 N phenol solution in 3% sodium or potassium alkali. Content of ammonia is determined visually by way of comparing intensity of adsorbent coloration with reference scale. Advantageously, indicator tube is used containing 0.2 g of HCl-activated silica gel and color reagent solutions 0.3 ml each. Special types of silica gel are used with grain size 0.2 mm. For more accurately determining ammonia content in air, ammonia adsorbed on silica gel is extracted, extract is treated by color reagents at volume ratio of extractant, phenol solution, and hypobromite solution 20:1:4, whereupon solution is photometered at 625 nm wavelength. EFFECT: decreased threshold of detectability, improved accuracy and reproducibility. 1 dwg, 3 tbl