Ultraviolet spectrophotometric characterization and bactericidal properties of electrolyzed oxidizing water as influenced by amperage and pH

To identify the primary component responsible in electrolyzed oxidizing (EO ) water for inactivation, this study determined the concentrations of hypoc hlorous acid (HOCl) and hypochlorite ions (OCl-) and related those concentr ations to the microbicidal activity of the water. The ultraviolet absorptio n spectra were used to determine the concentrations of HOCl and OCl- in EO water and the chemical equilibrium of these species with change in pH and a mperage. EO water generated at higher amperage contained a higher chlorine concentration. The maximum concentration of HOCl was observed around pH 4 w here the maximum log reduction (2.3 log(10) CFU/ml) of Bacillus cereus F443 1/73 vegetative cells also occurred. The high correlation (r = 0.95) betwee n HOCl concentrations and bactericidal effectiveness of EO water supports H OCl's role as the primary inactivation agent. Caution should be taken with standard titrimetric methods for measurement of chlorine as they cannot dif ferentiate the levels of HOCl present in EO water of varying pHs.