吸光度増加測定に基づく色素結合法による血清アルブミン定量のpH範囲

概要

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In the dye-binding method based on a protein error of a pH indicator, the upper-limit pH (pH_<UL>) at which an absorbance increase occurs exists. In the present work, the relationship between pH_<UL> and the buffer concentration in color reagent was investigated by a calculation and an experiment using four sulfonephthalein pH indicators. pH_<UL> was observed in reactions of all the dyes and human serum albumin ; it was not affected by the buffer concentration. In addition, the equilibrium constant did not affect pH_<UL>, suggesting that it does not change due to the kind of buffer. The pH_<UL> value was peculiar to each dye, and correlated moderately with the dissociation constants of each dye. The pH_<UL> changed only according to the ratio (ε_<PD>/ε_D) of the molar absorptivities between the dye-protein complex (ε_<PD>) and the dissociated dye anion (ε_D), and shifted to a higher pH due to an increase in its ratio. pH_<UL> was found to exist only when the ratio of the molar absorptivities was ε_<PD>/ε_D<1.
社団法人日本分析化学会の論文
2007-11-05