Flow-sonochemiluminescence method for antioxidant capacity analysis

A flow-sonochemiluminescence (SCL) method that offers a fast and simple alternative to the antioxidant capacity analysis is described. Reactive oxygen species (ROS) is generated reagentlessly and in situ in pH 7.4 phosphate buffer saline by ultrasound irradiating. Luminol reacts with the ROS to give SCL. The presence of antioxidant quenches the ROS, which in turn quenches the SCL. By quantifying SCL inhibition, the antioxidant capacity measurement can be achieved. Antioxidants including uric acid, l-ascorbic acid, tannic acid, l-cysteine, citric acid, salicylic, dl-sorbol and glutathione, are selected to test the presented method. Linear relationships between the quenched SCL intensity and antioxidant concentration, IC50 (half-inhibition concentration) of each antioxidant are obtained. Antioxidant capacities of six vegetables extracts (onion, potato, cabbage, carrot, cucumber and spinach) are evaluated. Under the optimized experiment condition, a high detection frequency of 590 h−1 is achieved. Intra- and inter-assay variability investigation shows relatively good precision of this flow-SCL method.