85. Solving a chemistry problem

85. After appropriate treatment of a sample of blood albumin weighing 50 mg, 50 ml of a protein hydrolyzate containing cystine (M HOOCCH (NH2)CH2S) 2 = 240.291 g/mol was obtained. We measured the height of the catalytic wave Id, - 14.5 μA at E = -1.6 V. 5.0 ml of a standard cystine solution with a concentration of 2.0 * 10-5 mol/l was added to the solution. The increase in the height of the catalytic wave at the same potential D. Id was 7.2 μA. Calculate the concentration (mg/kg) of cystine in albumin.
Task Weight of biological material, mg Diffusion current of the catalytic wave, Id , μA
85 50 14.5