Abstract: Stable formulations of alkyl benzidine compounds and methods of making and using same. To prepare a stable formulation, a short chain diol having fewer than six carbon atoms and an alkyl benzidine compound are combined together in solution at low pH and the solution is heated with moderate heat in the range of about 50° C. to 80° C. The stable formulation may contain dimers and/or trimers of the short chain diol. The stable formulation can be used to detect total chlorine in aqueous solution, to detect total chlorine in dialysis water, or as a colorimetric substrate in enzyme-linked immunosorbent assays.