As soon as the concentration of KMnO4 reaches to 1M or more, the spectra of HQ and SQ are nearly completely transformed into a single spectrum of BQ. It means that KMnO4 addition leads to catalytic oxidation of HQ into a final product BQ at 245.5nm. The BQ absorption at this wavelength (245.5nm) was confirmed by spiking the BQ solution to aqueous solution of HQ free of KMnO4. The same wavelength of 288nm has been described [18] for HQ determination in reversal first developer. The wavelength of 248 and 290nm has been described by Jiahai et al. [19] for BQ and HQ, respectively. Their quoted values are a little bit higher due to pH value of 2.9 they used for recording the UV spectra