A rapid method for microdetermination of hydrogen cyanide in air by means of detctor tubes

Abstract

Conventional methods for determining small amount of hydrogen cyanide in air are incovenient and timeconsuming. For the rapid determination of HCN, several granular gels which would change colors when exposed to air containing HCN were looked for. A detector reagent consisted of purified silica gel impregnated with HgCl₂ and Methyl Orange was found to have high sensitivity and stability in the determination of HCN in air. The gel was packed in a glass tube, and the sample air was drawn through it with a constant flow rate (1 ml/sec). Quantitative estimation was possible by measuring the colored length of the column. The range of determination is 1100 ppm HCN, and detecting limit is about 0.2 ppm. Mean relative error was below ± 5%. The results agreed well with those by the conventional colorimetric method.