Electrochemical determination of aripiprazole based on aluminium oxide nanoparticles modified carbon paste electrode

The electrochemical oxidation of aripiprazole was explored at a carbon paste electrode modified with aluminium oxide nanoparticles by cyclic voltammetry and square-wave anodic adsorptive stripping voltammetry. Experimental parameters such as carbon paste composition, scan rate, buffer pH, accumulation time, and accumulation potential were optimized in order to obtain high analytical performance. The incorporation of aluminium oxide nanoparticles into the carbon paste matrix enhanced the effective surface area of the carbon paste electrode and improved the sensitivity. On the aluminium oxide nanoparticles modified carbon paste electrode, aripiprazole exhibited an irreversible anodic peak at +1.17 V in pH 1.8 BR buffer solution. Under optimum conditions, the peak current exhibited a linear dependence with aripiprazole concentration between 0.03 and 8.0 µM with a detection limit of 0.006 ?M. The analytical applicability of the voltammetric method was evaluated by quantification of ARP in human serum samples and pharmaceutical formulations. © TÜBİTAKNKUBAP.01, YGLA.16.018This study was supported by Tekirdağ Namık Kemal University Scientific Research Projects Coodination Unit (project no: NKUBAP.01.YGLA.16.018)

Continuous wavelet transform methods for the simultaneous determinations and dissolution profiles of valsartan and hydrochlorothiazide in tablets

ABSTRACT Continuous wavelet transform (CWT) was proposed for the simultaneous determination and dissolution profiles of valsartan (VAL) and hydrochlorothiazide (HCT) in tablets, without the use of a chemical separation procedure. The CWT approach was applied to the original UV spectra and their ratio spectra in the optimal wavelength ranges. After testing several wavelet families, Mexican hat function-CWT and Daubechies7-CWT (mexh-CWT and db7-CWT, respectively) were found to be suitable for the transformation of the original UV spectra. In the following procedure, mexh-CWT and Coiflets3-CWT (coif3-CWT) were found to be appropriate for the signal analysis of ratio spectra (RS) of VAL/HCT and HCT/VAL. Calibration graphs for VAL and HCT were obtained by measuring db7-CWT and mexh-CWT amplitudes in the transformation of the original absorption spectra and RS-coif-CWT and RS-mexh-CWT amplitudes in the transformation of the ratio spectra. The validity and applicability of the proposed CWT methods were evaluated through the analysis of an independent set of synthetic binary mixtures consisting of VAL and HCT. The proposed signal processing methods were then successfully applied to the simultaneous quantitative evaluation and simultaneous dissolution profiles of the related drugs in commercial tablets, with good agreement reported for the experimental results

Electrochemical xanthine biosensor based on zinc oxide nanoparticles‒ multiwalled carbon nanotubes‒1,4-benzoquinone composite

Zinc oxide nanoparticles (ZnONPs), multiwalled carbon nanotubes (MWCNTs) and 1,4-benzoquinone (BQ) dispersed in chitosan (CS) matrix were used to construct a xanthine biosensor. Xanthine oxidase (XOx) was immobilized onto BQ-MWCNTs-ZnO–CS composite modified glassy carbon electrode (GCE) using glutaraldehyde as the crosslinking agent. The parameters of the construction process and the experimental variables for the biosensor were optimized. The xanthine biosensor showed an optimum response within 10 s, and the sensitivity was 39.4 μA/mMcm2 at +0.25 V (vs. Ag/AgCl). The linear working range of the biosensor was found to be 9.0×10−7-1.1×10−4 M with a detection limit of 2.1×10-7 M. The biosensor exhibited good long-term stability and reproducibility. The presented biosensor was also used for monitoring the freshness of chicken and beef flesh