Simultaneous determination of four(component by four-wavelength spectrophotometry

Four\|wavelength spectrophtometry is proposed to determine a four\|component mixture. The difference of absorbance of the three interferential components is zero, and Δ\%A=A\-\{λ1\}+K\-2A\-\{λ2\}+K\-3A\-\{λ3\}+K\-4A\-\{λ4\}\% is only linear with the concentration of the determined components at arbitrary wavelength combination. In order to reduce the error, the best wavelength combination is selected by a computer program. Thus, we can get a lot of data according to the error from minimum to maximum, and select the best wavelength in which the error is the smallest. This method can be used to determine the four components or monocomponents without separation yet with very satisfactory results. The analysis of synthesized samples consisting of p\|nitro\|phenol(PNP), p\|amini\|phenol(PAP), amino\|p\|acetyl phenol(APAP), and acetic acid shows a relative error below 5%. Hence, it has a certain application value.