The effect of detergents on chemical occult blood test.

Our previous investigation showed that toilet sanitizers and their main constituents, detergents, caused false negative reactions of the immunological occult blood test. Therefore, we investigated the effects of detergents on the chemical occult blood test. Twenty-nine kinds of detergents were added to a Hb solution and measured Hb concentration by a quantitative chemical occult blood test (modified colorimetric o tolidine method) and the results were compared with those by the immunological test. The detergents' effects on Hb spectra were also analyzed. The chemical test was affected slightly by most of the detergents tested although the immunological test was markedly to moderately affected. The spectrum of hemoglobin was not affected by the detergents examined except for the high concentrations of SDS and DTAB. The chemical occult blood test is affected by some detergents, but less than the immunological tests.