Application of xanthene derivatives for analytical chemistry. Part LXXX. Simple and sensitive spectrophotometric determination of albumin with o-sulfophenylfluorone-uranium(VI) complex, and binding study.

Abstract

A spectrophotometric method for the determination of albumin was established by using o-sulfophenylfluorone (SPF)-uranium(VI)(U(VI)) complex. This method can be used to determine 20-500μg/10 ml of human serum albumin (HSA), and is affected very little by the presence of globulin(as γ-globulin). Results obtained by the Bromocresol green (BCG) method and this method agree well with each other in artificial serum samples containing HSA and γglobulin, with the regression equation being Y (this method)=0.943X(BCG method)+ 1.20 (in mg HSA/dl, n=18, r=0.996).The propesed method is 6 times more sensitive than the BCG method, and has an advantage that deviation of responses of the reagent to albumins derived from the different animal species is small in comparison with that of Bromocresol purple. The binding parameters (n and K) were calculated from dual double-reciprocal plots. From the thermodynamic parameters (ΔG, ΔH and ΔS) obtained from a ven't Hoff plot, the binding between HSA and SPF-U(VI) complex or SPF was presumed to be a kind of hydrophobic interaction.