RESUMO
The effect of CdS quantum dots (QDs) on the electrochemiluminescence (ECL) signal of Ru(bpy)32+ was studied. It was found that CdS QDs could enhance the anodic ECL of Ru(bpy)32+ by 4 times. The sensitization mechanism was discussed and the influence factors including concentrations of Ru (bpy)32+ and CdS QDs, pH of solution and scan rate on ECL intensity were investigated. On the basis of quenching effect of catechol on the ECL signal of CdS QDs-Ru(bpy)32+,a system for sensitive determination of catechol was established with a detection limit of 5.5 nmol/L (S/N=3). This method was applied to the detection of catechol in tea sample with satisfactory results.
RESUMO
A novel electrochemiluminescence ( ECL) method for the determination of L-cysteine ( L-Cys) was established. water-soluble CdS quantum dots ( QDs) with Cd2+rich surface were synthesized via a controllable one-poe approach. The mercapto group in L-cysteine molecule can specifically interact with excessive Cd2+on the surface of CdS QDs, resulting in enhancement of ECL intensity of the CdS QDs, which can be used for the detection of L-Cys. Under the optimal experimental conditions, the enhancement of ECL intensity was linear with the concentration of L-Cys in the range of 5. 0×10-9-1. 0×10-5 mol/L. The limit detection of (S/N=3) was 1. 2×10-9 mol/L. In comparison with other methods for detecting L-Cys, this method is more simple and selective, and can be applied to detect L-Cys in real sample with satisfactory results.
RESUMO
A simple and straightforward method for the determination of dolasetron mesylate (DM) in aqueous solution was developed based on the fluorescence quenching of 3-Mercaptopropionic acid (MPA) capped CdS quantum dots (QDs). The structure, morphology, and optical properties of synthesized QDs were characterized by using UV-Vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Under the optimum conditions, the MPA-CdS QDs fluorescence probe offered good sensitivity and selectivity for detecting DM. The probe provided a highly specific selectivity and a linear detection of DM in the range of 2–40 μg/mL with detection limit (LOD) 1.512 μg/mL. The common excipients did not interfere in the proposed method. The fluorescence quenching mechanism of CdS QDs is also discussed. The developed sensor was applied to the quantification of DM in urine and human serum sample with satisfactory results.