Determination of proteins at nanogram levels by a resonance light-scattering technique with tetra-substituted sulphonated aluminum phthalocyanine

This is the first report on the determination of proteins with tetra-substi tuted sulphonated aluminum phthalocyanine (AlS4Pc) by resonance light-scatt ering (RLS). At pH 3.0, the weak RLS of AlS4Pc can be enhanced by the addit ion of proteins. Based on this, a novel quantitative method has been develo ped for the determination of proteins in aqueous solutions. Under optimal c onditions, the linear ranges of the calibration curves were 0.050-2.0 pg ml (-1) for both human serum albumin (HSA) and human r-IgG. The detection limi ts were 12.7 ng ml(-1) for HSA and 16.1 ng ml(-1) for human r-IgG. The meth od has been applied to the analysis of total protein in human serum samples collected from the hospital and the results were in good agreement with th ose reported by the hospital, which indicates that the method presented her e is not only sensitive, simple, but also reliable and suitable for practic al applications. (C) 2001 Elsevier Science B.V. All rights reserved.