No abstract

No abstract

The specific apparent capacitance (Farads per unit geometric area) of commercial carbon microdisc electrodes and in‐house fabricated carbon microcylinders is studied through the use of cyclic voltammetry. Home‐made microcylinder electrodes exhibit lower specific apparent capacitances and as a result facilitate lower limits of detection. We further demonstrate practically how the electroanalytical limit of the detection of solution phase trace oxygen is significantly improved using such microcylinder electrodes. Finally we show that after the degassing of a solution by nitrogen purging even in the most commonly encountered ‘best’ case scenarios approximately tens of μM of oxygen remain present in the electrochemical cell, unobservable by the commercial microdisc electrodes, but detectable with microcylinder electrodes, testifying to their analytical superiority.

No abstract

In this paper, a novel voltammetric method for the determination of 1,3-dimethylxanthine alkaloid theophylline is elaborated using differential pulse (DPV) and square-wave voltammetric (SWV) modes on a boron-doped diamond electrode. Direct oxidation of the analyte at very positive potentials was observed by cyclic voltammetry, as evidenced by the presence of a well-shaped irreversible peak at +1.63 V (vs. Ag/AgCl electrode) in 1 mol L À1 sulphuric acid. After optimization of experimental conditions, the current response of theophylline was proportionally linear from 2 to 380 mmol L À1 using both pulse techniques. The developed electroanalytical method yielded low detection limits of 0.91 and 1.45 mmol L À1 associated with good intra-day repeatability (relative standard deviation of 3.2 and 2.5%) using DPV and SWV, respectively. The influence of some possible interferents was also evaluated. The practical feasibility of the proposed methodology was tested in the analysis of pharmaceutical dosages and human urine samples and good recovery values were accomplished (93.2-102.5%). The results of analysis of pharmaceuticals were also in close agreement at a 95% confidence level with those obtained using the titration (reference) method. Taking these attributes into consideration, the proposed sensor may be employed as a simple and effective analytical tool in drug control analysis and analysis of biological samples as well as a useful alternative to previously utilized modified electrodes in this field.

In this work, the electrochemical oxidation and subsequent determination of uric acid was investigated using boron-doped diamond electrodes with various B/C ratios (0–2000 ppm).

A simple, rapid, and sensitive electroanalytical method for the direct quantification of folic acid was developed using square-wave voltammetry with a cathodically pretreated highly borondoped polycrystalline diamond electrode. The morphology and structure of this electrode were Downloaded by [University of Lethbridge] at 03:15 05 October 2015 2investigated by scanning electron microscopy and Raman spectroscopy. The electrochemical behavior of folic acid was studied by cyclic voltammetry and an irreversible oxidation peak was observed at +0.78 volt versus Ag/AgCl in Britton-Robinson buffer at pH 5. Using optimized square-wave voltammetry parameter values, the response of folic acid was linear from 0.1 to 167 micromolar with a limit of detection of 30 nanomolar with good repeatability. The influence of some interfering compounds was also evaluated. The method was successfully applied to the quantification of folic acid in pharmaceutical tablets. Considering the importance of the analyte upon human health, the boron-doped diamond electrode may be employed as an effective alternative electroanalytical approach.

This paper presents an electrochemical behavior study and quantification of fluoroquinolone antibiotic ciprofloxacin using boron-doped diamond electrode. Ciprofloxacin provides a diffusion-driven electrode reaction with an irreversible and poorly defined peak at +1.6 V vs. Ag/AgCl electrode in the presence of Britton-Robinson buffer solution pH 4. Applying differential pulse voltammetry (modulation amplitude of 60 mV, modulation time of 50 ms), the calibration curve with high linearity (R2 = 0.997) was obtained within the concentration range of (0.74 – 20.0) × 10−6 mol L−1 with the detection limit of 6.0 × 10−7 mol L−1 and repeatability expressed by relative standard deviation of 2.7 % (for 20 measurements). Interference study was performed to explore the selectivity of the elaborated procedure. By analysis of pharmaceutical dosages and model human urine samples, the ciprofloxacin content with the recovery values ranging from 88.4 to 121.2 % were determined. The developed approach using point-of-care electrochemical sensor based on boron-doped diamond material could represent inexpensive analytical alternative to separation methods and could be beneficial in analysis of biological samples and in the quality control in pharmaceutical industry.