A Simple Method for the Determination of Serum Albumin with an Animomic Dye 4'-hydroxyazobenzene-carboxylic Acid (2)

A new simple method for the determination of serum albumin employing a solution of an anionic dye 4-hydroxyazodenzence-cardoxylic acid (2) which compared quite well with the conventional salting-out (sodium sulfate) biuret method was presented. Three volumes of the dye solution (M/1000) were diluted with 2 volumes of the mixture of SORENSEN's M/15 phosphate buffer solution (pH 6.2), 8.0 g/dl sodium chloride solution and N/10 HCL (1:2.4:0.6), and to its 3.0 ml was added measured for its absorbance at 480 mμ against a blank consisting of 3.0ml of 0.9g/dl sodium solution. The absorbance of the serum (0.1 ml) diluted with 0.9g/dl sodium chloride solution (3.0ml) was similarly measured. The concentration of serum albumin was directly read from a calibration curve constructed with standard solutions made of bovine albumin, by applying the difference of the two absorbances. In case of jaundiced serum over 5 mg/dl in bilirubin concentration, the determination of serum albumin was corrected by adding 0.05 × bilirubin concentration (mg/dl)g/dl.