Simultaneous Determination:

Sometimes we come across a condition where in the analyte contains two species that have overlapping spectra. In sequence to determine these species we required to search two wavelengths whereas molar absorptivity of two species is different. In such a case, measurements are made on the solution of the analytes at two various wavelengths.

This provides a set of concurrent equations that could be solved for the concentrations of the individual constituents. For best outputs it is desirable to select two such wavelengths whereas the ratio of molar absorptivities is largest. Consider the spectra given within Figure.

Figure: Schematic UV spectra of analyte having two species with overlapping spectra