Flow Injection Determination of Ascorbic Acid by Iron(III)-Catalyzed Lucigenin Chemiluminescence in a Micellar System

Abstract

A flow-injection method is proposed for the determination of trace amounts of ascorbic acid. This method is based on the lucigenin chemiluminescence emitted by ascorbic acid in a basic medium. In this reaction the presence of iron(III) together with a nonionic surfactant Brij 35 (polyoxyethylene-23-lauryl ether), enhanced the intensity of the chemiluminescence signal to as high as 100-times compared to that in their absence. The present method allows the determination of ascorbic acid over the range 2.0×10^-7-6.0×10^-5mol dm^-3. The relative standard deviation was 1.9% for five determinations of 5.0×10^-6mol dm^-3 ascorbic acid; the detection limit (signal-to-noise ratio=3) was 2.0×10^-9 mol dm^-3 with a sampling rate of 30 samples h^-1.