Fluorimetric determination of albumin and globulin in human serum using tetra-substituted sulphonated aluminum phthalocyanine

A new method based on fluorescence quenching, employing a red-region fluorescent dye, tetra-substituted sulphonated aluminum phthalocyanine (AlS4Pc), is presented for the determination of albumin and: globulin without separation. Albumin was selectively determined at pH 3.0 at which globulin did not interfere. By subtracting the contribution of albumin from the total fluorescence change at pH 1.5, at which globulin was denatured, the content of globulin could be calculated. Factors including the acidity of media, reaction time, interference of non-protein substances as well as the methods for the denaturation of globulin which affected the determination were investigated. Under optimal conditions the linear ranges of the calibration curves were 0.1-4.0 mu g/ml for albumin and 0.2-6.0 mu g/ml for globulin, respectively. The detection limits were 0.04 mu g/ml for albumin and 0.07 mu g/ml for globulin. The method has been applied to the analysis of human serum samples collected from the hospital and the results were in good agreement with those reported by the hospital, indicating that the method presented here is not only sensitive and simple, but also reliable and suitable for practical applications. (C) 1999 Elsevier Science B.V. All rights reserved.