Simultaneous automated measurement of total 'antioxidant' (reducing) capacity and ascorbic acid concentration.

Biochemical tests of antioxidant status may be useful in measuring oxidative stress, however the time, skills and resources required for most such tests have limited their application and evaluation. In this study, newly available tests for two indices of antioxidant status, ferric reducing ability of plasma (FRAP) and ascorbic acid, were combined in one simple, rapid, automated test, referred to as FRASC. Results are available within 5 min of sample/reagent mixing. Linear dose-response is seen over a wide concentration range for both parameters. In- and between- run CVs were <1.0% and <3.0% respectively at 900-1800 μmol/l FRAP, and <5.0% for both at 20-400 μmol/l ascorbic acid. Mean (SD) FRAP values and ascorbic acid concentrations of fasting plasma from 130 healthy adults were 1018 (198) and 51 (18) μmol/l respectively. This combined test is straightforward and inexpensive, and lends itself to the measurement of 'antioxidant' (reducing) capacity and ascorbic acid concentrations of various biological fluids, as well as extracts of drugs and foodstuffs. FRASC will, therefore, facilitate experimental and clinical studies of pro-oxidant: antioxidant balance and oxidative stress-related disease.