Microdetermination of proteins by enhanced resonance light scattering spectroscopy of M-acetylchlorophosphonazo

A determination method of proteins with the limit of determination at nanogram levels is proposed by using a common spectrofluorometer to detect intensity of resonance light scattering (RLS). Under acidic conditions, the reaction between m-acetylchlorophosphonazo (CPA-mA) and proteins enhances the weak light scattering of CPA-mA drastically. The enhanced light scattering intensity is proportional to the concentration of proteins. The linear range of human serum albumin is 0.25-40.0 mug ml(-1). The determination of human serum and urine by this method give the results comparable with those by the Coomassie Brilliant Blue G-250 colorimetry (CBB) with relative standard deviations of 1.7-2.54% (n = 6). There is almost no interference from amino acids and most of the ions tested.