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

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).

Turn-on fluorescence probe for selective and sensitive detection of d-penicillamine by CdS quantum dots in aqueous media: Application to pharmaceutical formulation

“…In this connection, many mechanisms have been proposed for the design of sensors for various analytes, such as inorganic ions [37,38,[53][54][55][56][57], biomolecules [22,30,33] and active pharmaceutical ingredients [34,35] based on the surface states fluorescence modulation of QDs. Similarly, herein we have suggested that same approach can also be utilized for turn-on sensing of d-PA based on MPA-CdS QDs.…”

“…We have also reported a novel method for the quantitative determination of ranitidine hydrochloride (RNH) based on the fluorescence quenching of functionalized CdS quantum dots in aqueous solution [34]. Recently, an automated multi-pumping flow system is proposed for the chemiluminometric determination of ascorbic acid in pharmaceutical formulations by Sasaki et al [35]. So far, there are only few reports on QDs based turn-on fluorescent probe for anions [36,37] and biomedical [30] analysis.…”

A critical review on photochemical conversions in flow analysis

“…determined in pharmaceutical formulations [10]. Similar strategies were used for the determination of ascorbic acid [183], amoxicillin, diclofenac and caffeine [184], and estimative of the total antioxidant capacity [185]. An additional work demonstrated that a xenon flashlamp was more effective in the production of radicals for luminol A biosensor for glucose also exploited photo-electrochemical conversion after enzymatic generation of NADH [187].…”

Employment of electrochemically synthesized TGA–CdSe quantum dots for Cr3 determination in vitamin supplements

“…The analytical potential of QDs also has been explored [11,16,[20][21][22][23][24]. Because QDs are small and have a high surface area-to-volume ratio, their fluorescence is extremely sensitive to modifications on their surface.…”