Method of and device for analyzing one ingredient in a mixed solution

Abstract

A method of and device for analyzing one ingredient in a mixed solution with two light beams of different wavelengths are disclosed which include the following processes. A light beam from a light source are divided into a first light beam having a wavelength of .lambda..sub.1 and a second light beam having a wavelength of .lambda..sub.2. The wavelength .lambda..sub.1 is fixed, and .lambda..sub.2 is variable, for example, a scanning wavelength. Reference signals E.sub..lambda..sbsb.1 and E.sub.(.lambda..sbsb.2.sub.) respectively corresponding to the fixed wavelength .lambda..sub.1 and the variable wavelength (.lambda..sub.2) are produced from photometric signals resulting from the passage of the first and second light beams through only a solvent. After having been normalized by the reference signals E.sub..lambda..sbsb.1 and E.sub.(.lambda..sbsb.2.sub.), the photometric signals Ib.sub..lambda..sbsb.1 and Ib.sub.(.lambda..sbsb.2.sub.) resulting from the passage of the first and second light beams through a solution containing only a coexisting ingredient are converted into absorbance signals b.sub..lambda..sbsb.1 and b.sub.(.lambda..sbsb.2.sub.). These absorbance signals are held as a ratio indicating signal k.sub.(.lambda..sbsb.2.sub.) =b.sub.(.lambda..sbsb.2.sub.) /b.sub..lambda..sbsb.1. After having been normalized by the reference signals E.sub..lambda..sbsb.1 and E.sub.(.lambda..sbsb.2.sub.), the photometric signals Ic.sub..lambda..sbsb.1 and Ic.sub.(.lambda..sbsb.2.sub.) resulting from the passage of the first and second light beams through the mixed solution containing the coexisting ingredient and the ingredient to be analyzed are converted into absorbance signals C.sub..lambda..sbsb.1 and C.sub.(.lambda..sbsb.2.sub.). A product signal k.sub.(.lambda..sbsb.2.sub.).C.sub..lambda..sbsb.1 is produced from the absorbance signal C.sub..lambda..sbsb.1 and the ratio indicating signal k.sub.(.lambda..sbsb.2.sub.). A signal .DELTA.DS=a.sub.(.lambda..sbsb.2.sub.) -k.sub.(.lambda..sbsb.2.sub.).a.sub..lambda..sbsb.1 which can eliminate the influence of the coexisting ingredient, is produced from the absorbance signal C.sub.(.lambda..sbsb.2.sub.) and the product signal k.sub.(.lambda..sbsb.2.sub.).C.sub..lambda..sbsb.1. A signal .DELTA.S=a.sub.(.lambda..sbsb.2.sub.) /k.sub.(.lambda..sbsb.2.sub.) -a.sub..lambda..sbsb.1 which indicates the difference-absorbance spectrum of the ingredient to be analyzed, is produced from the signals .DELTA.DS and k.sub.(.lambda..sbsb.2.sub.).