In aqueous solutions of Chloramine T (CAT), caused by dissociation, hydrolysis and disproportionation processes, seven different kinds of molecules emerge (HOCl, OCl-, R-NCl-, R-NHCl, R-NCl2, R-NH2, and R-NH-[R = CH3-C6H4-SO2]). Their equilibrium concentrations have been calculated using an iteration process (polynom of 4th degree) as a function of cCAT (0.003-10%) and pH (0-14): - The (absol.) concentration of ''free chlorine'' ([HOCl]+[OCl-]) is surprisingly low showing a maximum concentration of HOCl in the whole concentration and pH range of only 2 . 10(-7) moles/l (0.014 ppm). - The relative equilibrium concentrations of the N-chlorinated toluene sulfonamide species R-NCl-, R-NHCl, and R-NCl2, virtually alone responsable for the oxidizing and by this also disinfecting properties, owing to the extremely low concentration of free chlorine, are influenced in the concentration range relevant for practice (> 0.1%) only by the pH-value: At pH > 7 the whole oxidation capacity is present as R-NCl- (pH 7: 99.6%; pH 8: 99.96%), while at pH < 3 it is formed by R-NHCl and R-NCl2. - On the basis of a valuation of the chlorinating power of the halogene containing species (establishment of estimates for the specific reactivities) conclusions concerning the general activity of CAT solutions against biological materials as a function of pH have been drawn, showing at pH greater-than-or-equal-to 8 a nearly constant (i.e. pH independent) reactivity, at pH < 8, however, an increase of reactivity can be expected, which nevertheless is limited by the decreasing solubility of the system CAT/H2O at pH < 7. The danger of skin injuries caused by unintended over-dosage as compared to hypochlorite, is therefore reduced to a great extent. - Toxic side effects caused by resorption processes largely can be excluded in the pH range 7-9, while the formation of chlorine covers typical for active chlorine compounds is not considered a toxic potential since the uppermost layer of the horny skin is renewed continuously. - In the light of a comparison with aqueous chlorine (hypochlorite) the advantages of CAT as a skin disinfectant are set forth. They are mainly founded on an acceptable compromise between sufficient microbicidal power and a low halogene demand and skin irritation.
