Colorimetric test element

摘要

A test element for calorimetric determination of oxidisable gaseous and/or vaporous components in gas mixtures contains an oxidising agent and a redox indicator which is present in the oxidised form. The redox indicator is preferably a benzidine derivative of the general formula: wherein R are the same or different and mean respectively hydrogen, alkyl, aryl, halogen, trifluoromethyl, cyano, nitro, dialkylamino, ester, sulphoxylic ester, alkyloxy or aryloxy, X is halogen, Y is trifluoromethyl, cyano, nitro, dialkylamino, ester, sulphoxylic ester, alkyloxy or aryloxy, n is a whole number from 0 to 3 and m equals 5 - n. The elements may be in the form of a tube containing the carrier onto which oxidising reagents and redox indicators are applied. The benzidine derivatives are claimed per se.