Determination of ultra trace amounts of protein by 4-chlorosulfo-(2'-hyaroxylphenylazo)-rhodanine-Ti(IV) complex [ClSARP-Ti(IV)] as the fluorescence spectral probe in AOT microemulsion.

Experiments indicated that protein can enhance the fluorescence of the 4-chlorosulfo-(2'-hydroxylophenylazo)-rhodanine-Ti(IV) complex [ClSARP-Ti(IV)] in the presence of bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) microemulsion. Based on this, a sensitive and reproducible fluorometric method for the determination of micro amount protein was developed. The calibration curves of four proteins were given. Under the optimum experimental conditions, the enhanced fluorescence intensity of the system was in proportional to the concentration of protein in the range of 0.1-11 microg mL(-1) for bovine serum albumin (BSA), 1.0-10 microg mL(-1) for human serum albumin (HSA), 1.0-50 microg mL(-1) for ovalbumin (Ova) and 2.5-18 microg mL(-1) for gamma-globulins (gamma-G). Their detection limits were 0.070, 0.071, 0.33 and 0.22 microg mL(-1), respectively. The ClSARP-Ti(IV) complex as a spectral probe can be used to the determination of protein in milk powder and oatmeal yielding with satisfactory results. Therefore, the proposed method is one of the most sensitive methods available. In addition, the interaction mechanism of this system is studied by multi-techniques.