Determination of Ascorbic Acid by Suppressed Chemiluminescence

This paper describes a method for determining ascorbic acid by the suppression of DTMC-H2O2 chemiluminescence. Various factors affecting the chemiluminescence determination of ascorbic acid were examined. Under the optimal conditions (1.2×10-4 mol· L-1 of DTMC, 5.0×10-5 mol·L-1 of H2O2, and pH 11.4 Na2HPO4-NaOH), the quenching of the chemiluminescent intensity was proportional to the concentration of ascorbic acid in the range of 1.0×10-7 - 8.0×10-6 mol·L-1, and the detection limit was 8.0× 10-8 mol·L-1 (S/N=3). The RSD was 4.6% for 1.0×10-6 mol·L-1 of ascorbic acid (n = 10). The selectivity of this method was high and no masking agent required *. The proposed method has been applied to the determination of ascorbic acid in real samples. The obtained results were in agreement with those by CuSO4-KI titration.