Effects of interfering gases in electrochemical sensors NH₃ and NO₂

The Main School of Fire Service, Faculty of Fire Safety Engineering, 52/54 Slowackiego St., 01-629 Warsaw, Poland

^* Corresponding author: mmajder@sgsp.edu.pl

Abstract

Electrochemical sensors used for toxic gas measurement. In this paper construction EC sensor and principle of operation has been described. The results of research on the influence of interfering gases on the readings of detectors containing ammonia and nitric oxide (IV) electrochemical sensors are presented. Span gases were used in the tests: 100 ppm CO, 25 ppm H₂S, 25 ppm NH₃, 10 ppm NO, 25 ppm NO₂, 10 ppm Cl₂, 10 ppm HCN, 10 ppm HCl, 2% vol. H₂, 2.5% by volume CH₄, 0.35% by volume of C₅H₁₂. The conducted research indicates that the presence of chlorine, hydrogen chloride, hydrogen cyanide, carbon monoxide and saturated hydrocarbons in the atmosphere does not affect the work of the ammonia electrochemical sensor. In the case of this sensor, there was a significant cross effect in relation to hydrogen sulphide and hydrogen. The administration of these substances indicated the presence of ammonia outside the measuring range (200 ppm). In the measurements using the NO₂ sensor, in most cases negative interference was found. The test results indicate that the measurements made with electrochemical sensors may be subject to error in the presence of interfering gases. The results obtained may be both understated and overstated.