METHOD OF INDICATING AND QUANTITATIVELY DETERMINING CHLORINE IN AIR Russian patent published in 1998 - IPC

FIELD: analytical methods. SUBSTANCE: air is pumped through silica gel treated by 0.15 N HCl solution and preliminarily wetted by water. Adsorbent is then treated by color reagent, namely by 0.02% o- toluidine in acetone. Concentration of chlorine in air sample is determined from adsorbent coloration intensity compared to reference coloration scale. Indicator tube is preferably utilized enclosing 0.2 g of activated silica gel (with grain size preferably 0.2 mm) and color reagent solution and distilled water 0.3 ml each. To further increase chlorine determination accuracy, adsorbed chlorine is extracted by water and then treated with color reagent at extractant to color reagent volume ratio 50:3, whereupon colored solution is photometered at 435 nm wavelength. EFFECT: lowered chlorine detection threshold and increased accuracy and reproducibility of determination. 4 cl, 1 dwg, 3 tbl