抄録
The behavior of color development of anionic azo dyes, Methyl Orange and its analogues, was examined in aqueous media by changing the micro-environment of the dyes. Organic onium ions brought about a decrease in the absorbance at wavelengths near 480nm (pH 6.5) and 500nm (pH 2) and an increase in the absorbance at wavelengths near 400nm. On the basis of this color change phenomenon, the spectrophotometric method for the determination of anionic surfactants was developed. Anionic surfactants (AS2-) react with quaternary ammonium ion to form stable ion associates (Q+•AS-) and the residual amount of Q- was determined with an azo dye by measuring the absorbance at about 400nm or 500nm. This spectrophotometric method was applied to the flow injection technique.
