Development of amperometric technique to detect antioxidant capacity in serum

Abstract

A simple and rapid amperometric method using screen-print carbon paste electrode (SCPE) and bias potential at 0.15V, was developed to determine the antioxidant capacity in serum. The 2,2’-azobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) was used as a free radical generator. ABTS•+ (ABTS cation radical) was generated from the reaction between ABTS and potassium persulfate (K2S2O8) at a molar ratio of 1: 0.25. The radical was stable at least 3 days when stored at 4⁰C in the dark. The developed method was used to determine antioxidant capacity in human serum. The reaction of ABTS•+ with antioxidant sample was measured, having Trolox as the standard antioxidant. After reaction between ABTS•+ and antioxidant sample, the residual ABTS•+ was measured for 100 seconds. The relationship between Trolox concentration and current signal was linear at the concentration range of 0-100 M. SCPE could be used at least thirty times with %RSD of 4.9%. This developed method was successfully used for determining antioxidant capacity of Thai normal subjects and patients. The average antioxidant capacity in sera of normal subjects and patients were determined to be 1486±66 and 1354±85 M TE, respectively. Moreover, the method could also be used for measuring antioxidant capacity of the spiked serum with -tocopherol.