A flow injection biamperometric method for determination of total antioxidant capacity of alcoholic beverages using bienzymatically produced ABTS+

Development of flow injection analysis (FIA) is reported for determination of total antioxidant capacity of alcoholic beverages (wines and spirits) by bienzymatically produced ABTS+ and electrochemical detector using interdigitated gold electrode (IDE). The method is based on biamperometric measurements using ABTS+∣ABTS redox couple. During the analysis, ABTS radical cation was bienzymatically produced by glucose-oxidase and peroxidase separately immobilized in tubular flow-through reactors. Influence of pH and substrate concentration on enzyme activity were tested in order to obtain the most sensitive mode. The effect of flow rate on operation of the bioreactors was also studied. The results of antioxidant capacity were expressed as Trolox Equivalent. The linearity of IDE detector was tested in the range between 20 μM and 2000 μM and good sensitivity of 0.165 nA/μM for Trolox solutions was obtained.Good comparison of results (R2 = 0.9942) was established for antioxidant capacity of tested samples between proposed FIA method and reference spectrometric measurements.