Flow-injection chemiluminescence determination of ascorbic acid by use of the cerium(IV)-Rhodamine B system

A highly sensitive flow-injection (FI) method with chemiluminescence (CL) detection is used for the determination of L-ascorbic acid. The method is based on the CL reaction of Rhodamine B with cerium(IV) in sulfuric acid media. L-Ascorbic acid is suggested to be a catalyst utilized in the energy-transferred excitation process. The proposed procedure allows quantitation of L-ascorbic acid in the range 3.8 x 10(-13) to 1.0 x 10(-10) mol l(-1) with a correlation coefficient of 0.9998 (n = 5) and relative standard deviation (R.S.D.) of 0.92% (n = 11) at 1.0 x 10(-11) mol l(-1). The detection limit (3 x blank) was 1.0 x 10(-13) mol l(-1). The method is successfully used to determine L-ascorbic acid in fresh vegetables. The possible mechanism of the chemiluminescence in the system is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.