ABSTRACT
The Electrochemical sensor based on carbon-clay paste electrode (CCPE) was constructed for sensitive determination of Tetracycline (Tc). The mineralogical composition, morphology, structure and performance of CCPE were characterized using X-ray diffraction powder, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Cyclic Voltammetry analysis. The CCPE is constituted of two types of clay having the ratio 1/1 and 2/1 characteristic of kaolinite and montmorillonite clay respectively. Its porous structure is ascribed to the presence of graphite. The CCPE exhibited a good electrocatalytic activity towards the oxidation of Tc. The electrochemical kinetics and mechanism of Tc were proposed, showing that Tc electrocatalytic oxidation reaction was controlled by diffusion process and took place in three steps. A low concentration of Tc was detected by amperometry with the linear ranges of 0.5µM-0.8 µM (R2 = 0.98), the sensitivity was 8.01 µA/µM.cm2, the limit of detection and quantification were 5.16x10-3µM(S/N = 3) and 1.72x10-2µM respectively. Thus, the proposed electrode provides a promising and prospective CCPE sensing platform for the detection of Tc in the environment.
ABSTRACT
In this work, a cyclic voltammetry analysis for the detection of Ascorbic Acid (AA) based on a carbon-clay paste electrode modified with titanium dioxide (CPEA/TiO2) is presented. The electrochemical sensor was prepared using clay and carbon graphite, mixed with TiO2 to investigate the electrode behavior towards the detection of AA. Comprehensive characterization approaches including X-ray diffraction (XRD), Selected area electron diffraction (SAED), Transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR) were carried out on different samples. The results indicated that, the electrode has been effectively modified, while the electrochemical parameters of AA on CPEA/TiO2/UV such as the charge transfer coefficient (α a ), number of electrons (n) transferred and standard potential were calculated. CPEA/TiO2/UV exhibit better photoactivity and also higher electronic conductivity under light radiation (100 W). The linear range for AA was determined between 0.150µM and 0.850 µM with the straight-line equation equivalent to I p a ( µ A ) = 2.244 [ A A ] + 1.234 (n = 8, R2 = 0.993). The limit of detection was 0.732 µM (3σ) and limit of quantification was 2.440 µM. For the analytical applications, pharmaceutical tablets such as Chloroquine phosphate, Azithromycin and Hydroxychloroquine sulfate were performed. In addition, interference study in the analytical application was performed, and it was found that the electroanalytical method used can be well adopted for simultaneous electrochemical detection of AA and Azithromycin.
ABSTRACT
Calcinated and acidified clay modified carbon graphite electrode was deployed in the simultaneous evaluation of traces of Pb2+ and Cd2+ in solution. After 5 minutes of accumulation in the circuit, the sensitivity of the electrode was evaluated in a solution of Na2SO4 (0.1 M) by square wave voltammetry on the one hand with Pb (II) and on the other hand with Cd (II). Several experimental conditions such as the composition of the carbon clay paste, the effect of preconcentration time, the sweeping speed, concentration effect, media pH, and interference ionic response to the electrochemical response of the working electrode were examined. It was observed that, after 5 minutes of preconcentration, detection limits of 0.15513 µmol·L-1 and 0.24227 µmol·L-1 were obtained for Pb2+ and Cd2+ in the electrolyte solution and 0.08438 µmol·L-1 and 0.46522 µmol·L-1, respectively, when tap water was used. The detection was effective by square wave voltammetry with a more intense current density with respect to lead.
