Chemiluminometric determination of ascorbic acid in pharmaceutical formulations exploiting photo-activation of GSH-capped CdTe quantum dots

• Published in: Luminescence (Chichester, England) Vol. 29; no. 7; pp. 901 - 907
• Main Authors: Sasaki, M. K., Ribeiro, D. S. M., Frigerio, C., Prior, J. A. V., Santos, J. L. M., Zagatto, E. A. G.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-11-2014; Wiley Subscription Services, Inc
• Subjects: Ascorbic acid; Ascorbic Acid - analysis; Cadmium Compounds - chemistry; Cadmium tellurides; Chemiluminescence; Chemistry, Pharmaceutical; Formulations; Glutathione - chemistry; Luminescent Measurements; Luminol - chemistry; Molecular Structure; multi-pumping flow system; pharmaceutical formulations; Pharmaceuticals; Photochemical Processes; Quantum Dots; Radicals; Reactive Oxygen Species; Semiconductors; Tellurium - chemistry; quantum dots; ascorbic acid; multi-pumping flow system; pharmaceutical formulations; chemiluminescence
• ISSN: 1522-7235; 1522-7243
• DOI: 10.1002/bio.2639

ABSTRACT
An automated multi‐pumping flow system is proposed for the chemiluminometric determination of ascorbic acid in pharmaceutical formulations, relying on the ability of semiconductor nanocrystals to generate short‐lived reactive species upon photo‐irradiation. A photo‐unit based on visible‐light‐emitting diodes is used to photo‐excite cadmium telluride (CdTe) quantum dots capped with glutathione, leading to the generation of radicals that react with luminol under alkaline conditions, yielding the chemiluminescence. Ascorbic acid acts as a radical scavenger, preventing the oxidation of luminol, thus ensuring a concentration‐dependent chemiluminescence quenching. After system optimization, a linear working range of 5.0 × 10‐7 to 5.0 × 10‐6 mol/L ascorbic acid (r = 0.9967, n = 5) was attained, with a detection limit of 3.05 × 10‐7 mol/L and a sampling rate of 200/h. The flow system was applied to the analysis of pharmaceutical formulations and the results were in good agreement with those obtained by the reference titrimetric procedure (RD < ± 4.3%, n = 7). Copyright © 2014 John Wiley & Sons, Ltd.