Abstract:

It is the most important problem of spectrophotometric analysis to determine two or more components in the same sample simultaneously without previous separation. In this respect, the absorbance derivative spectrophotometry is an analytical technique of great utility and offers greater selectivity than normal spectrophotometry. Recently, Salinas et al developed the absorbance ratio derivative spectra. The absorption spectrum of the mixture is divided by the absorption spectrum of a standard solution of one of the two or more components, and the first derivative of the ratio spectrum is obtained. The concentration of active component is then determined from a calibration graph obtained by measuring the amplitude at point corresponding to the minimum or maximum wavelength. In this way, the sensitivity of method is greatest.