Measurement of antioxidative activity against hypochlorite ion by sequential injection analysis with luminol chemiluminescence detection

A sequential injection analysis (SIA) with chemiluminescence detection for measuring the antioxidative activity against hypochlorite ion was developed. The antioxidative activity was expressed as the percentage inhibition of luminol chemiluminescence due to the scavenging of hypochlorite ion by an antioxidant. Using a 50 mM borate buffer (pH 9.5) as a carrier, he SIA system was optimized with respect to the reagent concentrations, volume and flow rates. The SIA system could measure 3 samples within 4 min. The relative standard deviations of the antioxidative activity for 2 nM ascorbic acid were 2.5% (within-day, n = 3) and 3.7% (between-day, n = 3). Several antioxidants, such as ascorbic acid, a-tocopherol and Trolox, were successfully measured by the SIA system, and the relationships between their antioxidative activity and the logarithm of concentrations of antioxidants were linear (r = 0.983 - 0.999). The proposed SIA system was rapid, sensitive and reproducible with minimum consumption of the reagents, and was thus useful for the rapid screening of antioxidants possessing antioxidative activity against hypochlorite ion.