Question

0.3 ml of a protein solution was diluted with 0.9 ml of water. To 0.5 ml of this diluted solution, 4.5 ml of BCA reagent was added and the color was allowed to develop. The absorbance of the mixture at 562 nm was 0.23 in a 1 cm cuvette. A standard solution (0.5 ml, containing 4 mg of protein per ml) plus 4.5 ml of BCA reagent gave an absorbance of 0.06 in a same-sized cuvette. What is the protein concentration in the undiluted unknown solution (our original 0.3 ml of protein)? Express your answer in mg/ml.

Answer 1

Solution :-

4 mg/ml solution gives absorbance at 0.06

and unknown solution gives absorbance at 0.23

threfore

concnetration of the unknown = 0.23 * 4 mg per ml / 0.06 = 15.33 mg/ ml

so the diluted solution has concnetration of the 15.33 mg/ml

volume of diluted solution = 0.3 ml +0.9 ml = 1.2 ml

now lets calculate the concnetration in original solution

concnetration of the original solution = 15.33 mg per ml * 1.2 ml / 0.3 ml = 61.32 mg/ml

So the concnetration of the original solution of protien is 61.32 mg/ml