INTERACTION OF ARSENAZO-III WITH SERUM-AL BUMIN

The interaction of arsenate III (AA III) with bovine serum albumin(BSA ) in acidic solution was investigated by a spectrophotometric method, It was considered that the electrostatic force between AA III and BSA is the main binding force, and that the color change during the reacti on is because of the transformation of AA III species from free H(6)L( 2-) form into bound H(5)L(3-) form. The apparent binding constant and the maximum binding number under tile conditions of pH 2.0, with 0.5% Nacl and without NaCl, were estimated respectively by using a linear r egression method proposed previously by the authors. The sensitivity o f detection for BSA was found to be about the same as that of the brom ocresol green method.