Determination of Total Antioxidant Capacity of Human Plasma from Patients with Lung Diseases Using Constant-Current Coulometry

Original coulometric method for total antioxidant capacity (TAC) determination based on the reaction of plasma antioxidants with electrogenerated bromine is developed. TAC is expressed in units of quantity of electricity (Coulombs) spent for titration per a liter of plasma. Coulomb is the universal unit of the TAC measurements because one can express TAC in units of different antioxidants using Faraday constant and the number of electrons involved in the reaction between antioxidant and electrogenerated bromine. The TAC in the plasma being determined for patients with different types of lung diseases is significantly lower than the one for control group. The data obtained by coulometry correlate with results of voltammetric determination based on oxidation of plasma on the glassy carbon electrode (Y=a + bX, where a=-6,7 +/- 0,5, b=1,07 +/- 0,04, R=0,9934). So, the proposed method could be recommended for clinical laboratories for estimation of antioxidant status and its subsequent correction using additional antioxidant therapy.