化学发光抑制法测定抗坏血酸

Determination of Ascorbic Acid by Suppressed Chemiluminescence

利用抗坏血酸对DTMC H2 O2 化学发光体系的抑制作用 ,研究了对抗坏血酸进行间接测定的可能性。试验发现 ,化学发光猝灭率 (R)与抗坏血酸浓度在 1 0× 10 - 7～ 8 0× 10 - 6 mol·L- 1 范围内呈线性关系 ,检出限达到 8 0× 10 - 8mol·L- 1 (S N =3)。对 1 0× 10 - 6 mol·L- 1 抗坏血酸进行 10次平行测定 ,其化学发光强度猝灭率相对标准偏差为 4 6 %。该猝灭体系不需要额外的掩蔽剂 ,方法简单、选择性好 ,可直接应用于一些食品中微量抗坏血酸的测定。

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 x 10(-4) mol. L-1 of DTMC, 5.0 x 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 x 10(-7)-8.0 x 10(-6) mol.L-1, and the detection limit was 8.0 x 10(-8) mol.L-1 (S/N=3). The RSD was 4.6% for 1.0 x 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.