A novel flow-injection chemiluminescence method for determination of baclofen using L-cysteine capped CdS quantum dots

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), transmission electron microscopy (TEM), photoluminescence (PL), and UV-vis spectroscopy. The L-cysteine capped CdS QDs sample displayed chemiluminescence (CL) emission in reaction with KMnO₄ in acidic medium. It was found that the CL intensity of KMnO₄-L-cysteine capped CdS QDs CL system was remarkably enhanced in the presence of Na₂S₂O₃. Furthermore, the possible CL mechanism was presented for this CL reaction according to results of the kinetic curves of CL systems, the spectra of CL, PL and UV-vis. The CL intensity of KMnO₄-L-cysteine capped CdS QDs-Na₂S₂O₃ was strongly inhibited in the presence of baclofen. Based on this inhibition, a novel and sensitive flow-injection CL method was developed for the determination of baclofen. Under optimum conditions, the CL intensity was inversely proportional to the concentration of baclofen in the range of 0.012-24.0 mg L^-1, with a detection limit (3σ) of 0.0035 mg L^-1. The analytical applicability of the proposed CL system was assessed by determining baclofen in spiked environmental water samples and pharmaceutical formulation. The analytical performances of proposed flow-injection CL method for the determination of baclofen were compared with those obtained by corona discharge ionization ion mobility spectrometry (CD-IMS) method. The proposed CL system had a higher sensitivity than the CD-IMS method for the determination of baclofen.