[Simultaneous determination of mixed phenol, catechol, and quinol by double Fourier transform filtering and second ratio spectra derivative spectrophotometry].

A new spectrophotometric method for the simultaneous determination of three compounds in the same sample is proposed. The method is based on the combination of double Fourier transform filtering with second ratio spectra derivative. Each absorption spectrum is filtered twice using the bigger filter window than in the filtering once. The ratio spectrum is obtained by dividing the amplitudes of the absorption spectrum of the mixture by a standard spectrum of one of the components and getting the first derivative of the ratio spectrum of the two compounds. Then the derivative is divided by the corresponding first derivative of one of the two compounds and the second derivative is obtained. The second derivative at certain wavelength is proportional only to the concentration of one compound. The effect of double Fourier transform filtering and the optimization of experimental parameters have been studied. The method has been applied to the simultaneous determination of 0.01009-0.05325 mg.mL-1 phenol, catechol and quinol in a solution. The relative errors are between 0.07% and 5.4%.