A BIURET REAGENT COMPOSED OF COPPER SULFATE, SODIUM HYDROXIDE AND AMMONIA FOR THE DETERMINATION OF SERUM PROTEIN

Levin-Brauer's biuret reagent consisted of copper sulfate, sodium hydroxide and ammonia was modified in composition to secure stable coloration when mixed with protein solution. An aliquot of 0.1ml.of blood serum was diluted with 2.0ml.of distilled water,and colorized with 4.0ml.of the improved biuret reagent. The absorbance was read,five to fifteen minutes after mixing,in a photoelectric colorimeter with a filter whose maximum transmission was at 570 mu to obtain the concentration of total serum protein.For the determination of albumin and globulin in serum theprocedure was conpled with the sodium sulfatesalting out method of Milne.The coloration attained to maximum stability with this roagent within shorter period of time than with Weichelbaum's.The results were in satisfactory accordance with those of azotometry.