Carbon film resistor electrode for amperometric determination of acetaminophen in pharmaceutical formulations

Voltammetric determination of paracetamol in tablet formulation using Fe (III) doped zeolite-graphite composite modified GCE

Although paracetamol is known to have excellent safety profile at recommended therapeutic doses, health effects are also reported at acute overdoses. A sensitive and selective voltammetric method using Fe(III) encapsulated zeolite/graphite composite modified glassy carbon electrode is presented in this work for the determination of paracetamol in tablet formulations. In contrast to the unmodified electrode, a fourfold increase of cyclic voltammetric oxidative peak current paralleled by reduced potential difference (ΔE _p ) at the modified electrode confirmed electrocatalytic property of the modifier towards oxidation of paracetamol. The oxidative peak current showed linear dependence on concentration range 0.5-200 μM with R ² and LOD of 0.9989 and 0.01 μM, respectively. The paracetamol content of four brands of tablet samples was found in the range 95.95 ± 0.23-103 ± 0.52% of the theoretical values. Recovery results between 94.54 ± 0.82 and 102 ± 0.34% for spiked paracetamol in tablet samples validated the selectivity of the method for determination of paracetamol in real samples.

Electrochemical properties of the acetaminophen on the screen printed carbon electrode towards the high performance practical sensor applications

Acetaminophen is a non-steroidal anti-inflammatory drug used as an antipyretic agent for the alternative to aspirin. Conversely, the overdoses of acetaminophen can cause hepatic toxicity and kidney damage. Hence, the determination of acetaminophen receives much more attention in biological samples and also in pharmaceutical formulations. Here, we report a rapid and sensitive detection of the acetaminophen based on the bare (unmodified) screen printed carbon electrode (BSPCE) and its electrochemistry was studied in various pHs. From the observed results, the mechanism of the electro-oxidation of acetaminophen was derived for various pHs. The acetaminophen is not stable in strong acidic and strong alkaline media, which is hydrolyzed and hydroxylated. However, it is stable in intermediate pHs due to the dimerization of acetaminophen. The kinetics of the acetaminophen oxidation was briefly studied and documented in the schemes. In addition, the surface morphology and disorders of BSPCE was probed by scanning electron microscope (SEM) and Raman spectroscopy. Moreover, the BSPCE determined the acetaminophen with the linear concentration ranging from 0.05 to 190μM and the lower detection limit of 0.013μM. Besides that it reveals the good recoveries towards the pharmaceutical samples and shows the excellent selectivity, sensitivity and stability. To the best of our knowledge, this is the better performance compare to the previously reported unmodified acetaminophen sensors.

Investigating the properties of subcritical water extraction with pharmaceutical tablets

The properties of subcritical water extraction (SWE) in the sample preparation of pharmaceutical tablets were investigated. Tablets comprised of microcrystalline cellulose excipients broke apart up to 80 times faster in subcritical water than they did in room temperature water, while those containing starch readily broke apart in either. Tablets containing starch were also observed to gelatinize or “paste” over several SWE conditions, impeding subsequent filtration and analysis. This effect was avoidable, however, since it was demonstrated to disappear with increases in extraction time and temperature or decreases in sample size. Using SWE, two common over-the-counter pharmaceuticals were extracted under optimized conditions from tablets comprised of either microcrystalline cellulose or starch excipients. Analyte recoveries of 95% or more were obtained at 150 °C for vitamin C (ascorbic acid) tablets in as little as 8 min for the extraction of a whole intact tablet, 6 min for two half tablets, and 5 min for a ground tablet. By comparison, this occurred at 250 °C in just 2 min for an intact slice of an acetaminophen tablet. Reproducibility was generally quite good with these trials producing RSD values of less than 2%. The results indicate that SWE can be a potentially viable and efficient method for the sample preparation of whole, sliced, or ground pharmaceutical tablets, and further exploration of this approach is promising.

Stripping Voltammetric Determination of Analgesics in Their Pharmaceuticals Using Nano-Riboflavin-Modified Glassy Carbon Electrode

Cyclic voltammetric behaviors of three analgesics, acetaminophen (AAP), acetylsalicylic acid (ASA), and dipyrone (DP), were studied using nano-riboflavin-modified glassy carbon electrode. One well-defined oxidation peak each for AAP and ASA and three oxidation peaks for DP were observed. The influence of pH, scan rate, and concentration reveals irreversible diffusion controlled reaction. The SEM analysis confirmed good accumulation of the drugs on the electrode surface. Calibration was made under the maximum peak current conditions. The concentration range studied for the determination of drugs was 0.02 to 0.4 μg mL−1for AAP and ASA and 0.025 to 0.4 μg mL−1for DP. The lower limit of detection observed for AAP, ASA, and DP was 0.016, 0.007 μg mL−1, and 0.013 μg mL−1, respectively. The suitability of the method for the determination of these analgesics in pharmaceutical preparations and urine samples was also ascertained.

Voltammetric Determination of Acetaminophen in the Presence of Codeine and Ascorbic Acid at Layer-by-Layer MWCNT/Hydroquinone Sulfonic Acid-Overoxidized Polypyrrole Modified Glassy Carbon Electrode

A very sensitive electrochemical sensor constructed of a glassy carbon electrode modified with a layer-by-layer MWCNT/doped-overoxidized polypyrrole (oppy/MWCNT /GCE) was used for the determination of acetaminophen (AC) in the presence of codeine and ascorbic acid (AA). In comparison to the bare glassy carbon electrode, a considerable shift in the peak potential together with an increase in the peak current was observed for AC on the surface of oppy/MWCNT/GCE, which can be related to the enlarged microscopic surface area of the electrode. The effect of the experimental conditions on the electrode response, such as types of counter ion, pyrrole and counter ion concentration, potential and number of cycles in the polymerization procedure, amount of MWCNT, and the pH, were investigated. Under the optimized conditions, the calibration curve was obtained over two concentration ranges of 2 × 10−7–6 × 10−6 M and 4 × 10−5–1 × 10−4 M of AC with a linear correlation coefficient (R2) of 0.9959 and 0.9947, respectively. The estimated detection limit (3σ) for AC was obtained as 5 × 10−8 M. The developed method was successfully applied to analyze the pharmaceutical preparations of AC, and a recovery of 95% with a relative standard deviation of 0.98% was obtained for AC.

Development of a Method for a Sensitive Simultaneous Determination of Dopamine and Paracetamol in Biological Samples and Pharmaceutical Preparations

A chemically modified electrode is constructed based on multiwalled carbon nanotube—modified glassy carbon electrode (MWCNTs/GCE). The measurements were carried out by application of differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometry (CA) methods. Application of DPV method showed wide linear range of DA from 1 μM to 540 μM and a detection limit of 0.098 μM (S/N=3). The linear range of PAR of 3 μM to 300 μM and a detection limit of 0.15 μM, were obtained. The modified electrode showed electrochemical responses with high sensitivity, high selectivity, and excellent stability for DA and PAR determination at optimal conditions, which makes it a suitable sensor for simultaneous submicromolar detection of DA and PAR in solutions. The analytical performance of this sensor has been evaluated for detection of DA and PAR in human serum, human urine, and pharmaceutical preparation with satisfactory results.

Electrochemical biosensors in pharmaceutical analysis

Given the increasing demand for practical and low-cost analytical techniques, biosensors have attracted attention for use in the quality analysis of drugs, medicines, and other analytes of interest in the pharmaceutical area. Biosensors allow quantification not only of the active component in pharmaceutical formulations, but also the analysis of degradation products and metabolites in biological fluids. Thus, this article presents a brief review of biosensor use in pharmaceutical analysis, focusing on enzymatic electrochemical sensors.

Electrochemical study and flow injection analysis of paracetamol in pharmaceutical formulations based on screen-printed electrodes and carbon nanotubes

Acetaminophenol or paracetamol is one of the most commonly used analgesics in pharmaceutical formulations. Acetaminophen is electroactive and voltammetric mechanistic studies for the electrode processes of the acetaminophenol/N-acetyl-p-quinoneimine redox system are presented. Carbon nanotubes modified screen-printed electrodes with enhanced electron transfer properties are used for the study of the electrochemical-chemical oxidation mechanism of paracetamol at pH 2.0. Quantitative analysis of paracetamol by using its oxidation process (in a Britton-Robinson buffer solution pH 10.0) at +0.20 V (vs. an Ag pseudoreference electrode) on an untreated screen-printed carbon electrode (SPCE) was carried out. Thus, a cyclic voltammetric based reproducible determination of acetaminophen (R.S.D., 2.2%) in the range 2.5x10(-6) M to 1x10(-3) M, was obtained. However, when SPCEs are used as amperometric detectors coupled to a flow injection analysis (FIA) system, the detection limit achieved for paracetamol was 1x10(-7) M, one order of magnitude lower than that obtained by voltammetric analysis. The repeatability of the amperometric detection with the same SPCE is 2% for 15 successive injections of 10(-5) M acetaminophen and do not present any memory effect. Finally, the applicability of using screen-printed carbon electrodes for the electrochemical detection of paracetamol (i.e. for quality control analysis) was demonstrated by using two commercial pharmaceutical products.

Simultaneous Chronoamperometric Sensing of Ascorbic Acid and Acetaminophen at a Boron-Doped Diamond Electrode

Cyclic voltammetry (CV) and chronoamperometry (CA) have been used to sense and determine simultaneously L-ascorbic acid (AA) and acetaminophen (AC) at a boron-doped diamond electrode (BDDE) in a Britton-Robinson buffer solution. The calibration plots of anodic current peak versus concentration obtained from CV and CA data for both investigated compounds in single and di-component solutions over the concentration range 0.01 mM – 0.1 mM proved to be linear, with very good correlation parameters. Sensitivity values and RSD of 2-3% were obtained for various situations, involving both individual and simultaneous presence of AA and AC. The chronoamperometric technique associated with standard addition in sequential one step and/or two successive and continuous chronoamperograms at two characteristic potential levels represented a feasible option for the simultaneous determination of AA and AC in real sample systems such as pharmaceutical formulations. The average values indicated by the supplier were confirmed to a very close approximation from chronoamperomgrams by using several additions with the application of suitable current correction factors.