Aging Aging

138 Benzie and StrainTable 2FRAP Values and Ascorbic Acid Concentrations(Mean; Median; SD; µmol/L), Using FRASC, of Fresh FastingEDTA Plasma from Healthy SubjectsAll (n = 130) Men (n = 66) Women (n = 64)Age (years) 43; 43; 16.4 42; 42; 16.3 43; 44; 16.6FRAP 1018; 1004; 198 1086; 1077; 189 948; 927; 183Ascorbic acid 51; 48; 17.9 49; 48; 13.8 52; 50; 21.3Reproduced with permission from Benzie, I. F. F. and Strain, J. J. (1997) Redox Report 3,233–238.Using the paired water (–ao) and ascorbate oxidase diluted (+ao) samples, theascorbic acid concentration is calculated as follows:0–1 min ascorbic acid related change in A 593 nm = (2)(0–1 min A 593 nm sample –ao) – (0–1 min A 593 nm sample +ao)ascorbic acid concentration (µM) = [ascorbic acid] std (µM) × (3)0–1 min ascorbic acid related A 593 nm of test sample /0–1 min ascorbic acid related A 593 nm of standard(see Note 8).nonascorbic acid antioxidant power = (4)FRAP value (µM) – 2 × ascorbic acid concentration (µM)Table 2 gives typical values obtained on fasting plasma samples from healthyadults.4. Notes1. The TPTZ powder, as purchased, is normally white. However, in some bottles,when opened, the contents have been found to be gray or yellow in color.The reason for this coloration is not clear, but it does not appear to affect results.The working FRASC reagent should be a pale yellow/orange color. Any visibleblue color indicates contamination by either ferrous iron or a reducing agent.Visible blue color in the working reagent will give a high blank reading anddecrease sensitivity: do not use.2. Do not attempt to use Fe II standards >1500 µM, as there will be precipitation ofiron salts. Aqueous ferrous sulfate solutions of up to 1500 µM appear to be stablefor at least 1 mo at 4°C. These solutions should be clear and colorless.3. It is important that ALL samples, calibrators, and QC samples be treated identicallyand in matching ascorbate oxidase diluted and water diluted pairs. The sameabsorbance reading should be obtained for the paired Fe II solutions, that is, the