Determination of dexamethasone by flow-injection chemiluminescence method using capped CdS quantum dots

• Synthesis and characterization of l-cysteine capped CdS quantum dots (QDs).
• CL reaction of l-cysteine capped CdS QDs with KMnO4 as efficient oxidizing agent.
• Dexamethasone determination using KMnO4-capped CdS QDs flow-injection CL system.

l-Cysteine capped CdS quantum dots (QDs) were synthesized through a facile hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and UV–Vis spectroscopy. The light emitted from KMnO4–l-cysteine capped CdS QDs reaction in acidic medium was applied as a simple and sensitive chemiluminescence (CL) system for determination of dexamethasone. The CL intensity of KMnO4–l-cysteine capped CdS QDs CL system was remarkably enhanced in the presence of dexamethasone. Under optimum experimental conditions, the enhanced CL intensity was related to dexamethasone concentration in the range of 0.004–25.0 mg L−1, with the detection limit (3σ) of 0.0013 mg L−1. The analytical applicability of the proposed CL system was assessed by determining dexamethasone in spiked environmental water samples and pharmaceutical formulation. The analytical performances of proposed flow-injection CL method for the determination of dexamethasone were compared with those obtained by corona discharge ionization ion mobility spectrometry (CD-IMS) method. The proposed CL system exhibits a higher sensitivity and precision than the CD-IMS method for the determination of dexamethasone.

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