Voltammetric determination of atenolol at C60-modified glassy carbon electrodes

Derivatization-free conventional and synchronous spectrofluorimetric estimation of atenolol and amlodipine

Fixed-dose combinations for treatment of hypertension are observed in many dosages in the global market because of their high efficacy compared to single component dosage forms. One of these effective combinations is atenolol/amlodipine which is usually administered to patients with hypertension. Hence, development of facile, accurate, and sensitive methods for simultaneous estimation of atenolol and amlodipine is of great importance for quality control testing and pharmacokinetic studies. In our study, we developed two spectrofluorimetric methods to estimate both compounds in different pharmaceuticals. The first method is based on the estimation of atenolol and amlodipine by double-scan conventional spectrofluorimetry where the fluorescence intensities of atenolol and amlodipine were measured at 299 and 434 nm after excitation at 274 and 358 nm, respectively. The second method depends on synchronous spectrofluorimetric measurements at Δλ = 70 nm, where atenolol is assayed at 266 nm and amlodipine is assayed at 363 nm. Methods' optimizations were carried out to select the optimum conditions that render high selectivity and sensitivity. Such optimizations included assessment of solvents, surfactants, buffer volumes and pHs. The conventional spectrofluorimetric method was rectilinear over concentration range of 30.0-300.0 ng mL-1 for atenolol and 0.25-7.00 µg mL-1 for amlodipine while the synchronous spectrofluorimetric method showed linearity over the ranges of 0.60-6.00 µg mL-1 for atenolol and 0.25-7.00 µg mL-1 for amlodipine with low detection limits (≤0.12 µg mL-1) for both compounds in the two methods. It is the first work that demonstrates estimation of atenolol and amlodipine in their combinations by conventional and synchronous spectrofluorimetry. Both methods were applied to estimate atenolol and amlodipine in different pharmaceuticals with high %recovery and low %RSD.

Label-free green estimation of atenolol and ivabradine hydrochloride in pharmaceutical and biological matrices by synchronous spectrofluorimetry

In this work, a label-free, rapid, and sensitive synchronous spectrofluorometric method was implemented to assay atenolol (ATL) and ivabradine hydrochloride (IVB) in pharmaceutical and biological matrices. Simultaneous determination of ATL and IVB by conventional spectrofluorometry cannot be implemented because of the clear overlap of the emmision spectra of ATL and IVB. To overcome this problem, synchronous fluorescence measurements at a constant wavelength difference (Δλ) combined with mathematical derivatization of the zero order spectra were perforemed. The results indicated a good resolution between emission spectra of the studied drugs when the first-order derivative of the synchronous fluorescence scans at Δλ = 40 nm was conducted using ethanol as the optimum solvent which is less hazardous than other organic solvents such as methanol and acetonitrile, keeping the method safe and green. The amplitudes of the first derivative synchronous fluorescent scans of ATL and IVB in ethanol were monitored at 286 and 270 nm to simultaneously estimate ATL and IVB, respectively. Method optimisation was conducted by assessing different solvents, buffer pHs, and surfactants. The optimum results were obtained when ethanol was utilized as a solvent without using any other additives. The developed method was linear over concentration ranges of 10.0-250.0 ng mL^-1 for IVB and 100.0-800.0 ng mL^-1 for ATL with detection limits of 3.07 and 26.49 ng mL^-1 for IVB and ATL, respectively. The method was utilized to assay the studied drugs in their dosages and in human urine samples with acceptable % recoveries and RSD values. The greenness of the method was implemented by three approaches involving the recently reported metric (AGREE) which ensured the eco-freindship and safety of the method.

An ultra-sensitive laccase/polyaziridine-bismuth selenide nanoplates modified GCE for detection of atenolol in pharmaceuticals and urine samples

The analysis of β-blockers in pharmaceutical, biological and environmental samples has gained much interest due to their wide applications. The aim of this study was to develop an enzyme-based biosensor using hexagonal-shaped low-dimensional Bi₂Se₃ NPs decorated with laccase through polyaziridine (PAZ) modified glassy carbon electrode (Lac/PAZ-Bi₂Se₃ NPs/GCE). Surface properties were examined using SEM, TEM, EDX, XRD, XPS, FTIR, UV-Visible, and zeta potential. Electrochemical studies were performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The enzymatic biosensor exhibited excellent catalytic activity towards the oxidation of ATN at +1.05 V (vs Ag/AgCl). Under the optimum experimental conditions, I_p (µA) was linearly related to the concentrations of ATN in the range of 3 to 130 µM (R² = 0.9972) with an LOD of 0.15 µM and 0.21 µM with and without Lac enzyme. Additionally, the validation of the biosensor was tested to determine ATN on within a day and between-day basis. The biosensor was applied successfully to detect ATN in real samples. The obtained recoveries range from 98.5 % to 99.2 % with an RSD (n = 5) of 0.95 (±0.02). The findings of this study have potential biomedical applications in drug detection employing a promising nano electrode sensor of Lac/PAZ-Bi₂Se₃ NPs/GCE.

Electrochemical determination of atenolol and propranolol using a carbon paste sensor modified with natural ilmenite

In this study, a simple voltammetric method was reported for independent determination of propranolol (PROP) and atenolol (ATN) in pharmaceutical tablets using carbon paste electrode modified with natural Ilmenite (CPE-I). The analytical performance of the modified sensor was evaluated using the square wave voltammetry and cyclic voltammetry for determination of both β(beta) blockers in 0.1 mol L−1 of sulfuric acid solution (H2SO4). The signal obtained with modified carbon paste electrode in 0.1 mol L−1 of H2SO4 showed a good electrocatalytic activity toward the oxidations of PROP and ATN compared with the bare one. The enhanced oxidation peak current response can be attributed to the catalytic effect of the ilmenite nanomaterial incorporated into the carbon paste electrode. Under optimal condition, good linear calibration curves were obtained ranging from 0.20 to 8.9 mmol L−1 for PROP and 2.0 to 9.9 µmol L−1 for ATN, with detection limits of 80 and 0.31 µmol L−1, respectively. The CPE-I sensor had good repeatability and reproducibility (RSD ≤ 3.2%) and high sensitivity for the detection of both ATN and PROP. The proposed sensor was applied for detection of these drugs in pharmaceutical tablets. The obtained results indicate that the voltammetric CPE-I sensor could be an alternative method for the routine quality control of the β blockers in complex matrices.

An Ultimate Investigation on the Adsorption of Amantadine on Pristine and Decorated Fullerenes C59X (X=Si, Ge, B, Al, Ga, N, P, and As): A DFT, NBO, and QTAIM Study

In this investigation, the feasibility of detecting the amantadine (AMD) molecule onto the outer surface of pristine fullerene (C[Formula: see text]), as well as C[Formula: see text]X ([Formula: see text], Ge, B, Al, Ga, N, P, and As) decorated structures, was carefully evaluated. For achieving this goal, a density functional theory level of study using the HSEH1PBE functional together with a 6-311G(d) basis set has been used. Subsequently, the B3LYP-D3, wB97XD and M062X functionals with a 6-311G(d) basis set were also employed to consider the single point energies. Natural bond orbital (NBO) and the quantum theory of atoms in molecules (QTAIM) were implemented using the B3LYP-D3/6-311G(d) method and the results were compatible with the electronic properties. In this regard, the total density of states (TDOSs), the Wiberg bond index (WBI), natural charge, natural electron configuration, donor–acceptor NBO interactions, and the second-order perturbation energies are performed to explore the nature of the intermolecular interactions. All of the energy calculations and population analyses denote that by adsorbing of the AMD molecule onto the surface of the considered nanostructures, the intermolecular interactions are of the type of strong physical adsorption. Among the doped fullerenes, Ge-doped structure has very high adsorption energy compared to other elements. Generally, it was revealed that the sensitivity of the adsorption will be increased when the AMD molecule interacts with the decorated fullerenes and decrease the HOMO–LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanocarrier.

Green synthesis and characterization of DyMnO3-ZnO ceramic nanocomposites for the electrochemical ultratrace detection of atenolol

The present study is a first report about magnetic, optical and electrical as well as drug sensing properties of DyMnO₃-ZnO green-nanocomposites that are synthesized by Pechini modified method. Three natural compounds containing Vitis vinifera, Hibiscus sabdariffa and rhus juices are used as green and eco-friendly reagents for synthesis of the nanostructures. The nanostructures are characterized by various techniques containing Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), field emission scanning electron microscopes (FESEM), high resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometer (VSM) and diffuse reflectance spectroscopy (DRS). The calcination temperature, type of chelating agent and pH are optimized to achieve the best structural and smallest crystallite sizes of the systems via an eco-friendly approach. The studies show that the Vitis vinifera juice creates the best homogeneous sphere-like nanostructures. Therefore, the samples that are synthesized by Vitis vinifera juice are used for fabrication of a carbon paste electrode modified with DyMnO₃-ZnO nanocomposites (DMZN/CPE). The nanostructured modified electrode exhibits an excellent electrocatalytic effect for determination of atenolol (ATN) using voltammetry techniques. The results reveal that the DyMnO₃-ZnO green-nanocomposites have potential applications as a sensitive material in the drug analysis in biological samples.

Voltammetric Techniques for the Analysis of Drugs using Nanomaterials based Chemically Modified Electrodes

Background:

Electroanalytical techniques play a very important role in the areas of medicinal, clinical as well as pharmaceutical research. Amongst these techniques, the voltammetric methods for the determination of drugs using nanomaterials based chemically modified electrodes (CMEs) have received enormous attention in recent years. This is due to the sensitivity and selectivity they provide on qualitative as well as quantitative aspects of the electroactive analyte under study. The aim of the present review was to discuss the work on nanomaterials based CMEs for the analysis of drugs covering the period from 2000 to present employing various voltammetric techniques for different classes of the drugs.

Methods:

The present review deals with the determination of different classes of drugs including analgesics, anthelmentic, anti-TB, cardiovascular, antipsychotics and anti-allergic, antibiotic and gastrointestinal drugs. Also, a special section is devoted for enantioanalysis of certain chiral drugs using voltammetry. The detailed information of the voltammetric determination for the drugs from each class employing various techniques such as differential pulse voltammetry, cyclic voltammetry, linear sweep voltammetry, square wave voltammetry, stripping voltammetry, etc. are presented in tabular form below the description of each class in the review.

Results:

Various nanomaterials including carbon nanotubes, graphene, carbon nanofibers, quantum dots, metal/metal oxide nanoparticles, polymer based nanocomposites have been used by researchers for the development of CMEs over a period of time. The large surface area to volume ratio, high conductivity, electrocatalytic activity and biocompatibility make them ideal modifiers where they produce synergistic effect which helps in trace level determination of pharmaceutical, biomedical and medicinal compounds. In addition, macrocyclic compounds as chiral selectors have been used for the determination of enantiomeric drugs where one of the isomers captured in the cavities of chiral selector shows stronger binding interaction for one of the enantiomorphs.

Conclusion:

arious kinds of functional nanocomposites have led to the manipulation of peak potential due to drug - nanoparticles interaction at the modified electrode surface. This has facilitated the simultaneous determination of drugs with almost similar peak potentials. Also, it leads to the enhancement in voltammetric response of the analytes. It is expected that such modified electrodes can be easily miniaturized and used as portable, wearable and user friendly devices. This will pave a way for in-vivo onsite real monitoring of single as well as multi component pharmaceutical compounds.

Simultaneous determination of nifedipine and atenolol in combined dosage forms using a boron-doped diamond electrode with differential pulse voltammetry

Combinations of nifedipine (NIF) and atenolol (ATN) are used for the treatment of arterial hypertension. Dosages values different from those presented on the label of pharmaceuticals can significantly impact a consumer’s health. To control the quality of the pharmaceuticals effectively, a method for the simultaneous determination of these both drugs using an anodically pretreated boron-doped diamond electrode coupled to differential pulse voltammetry technique was developed. The influence of supporting electrolyte, pH and scan rate on the current response of these both antihypertensives was examined to select the optimum experimental conditions. It was found that NIF and ATN provided two well-shaped and reproducible oxidation peaks at 0.97 V and 1.36 V (vs. Ag/AgCl electrode), respectively, in TRIS buffer solution (pH 8.0). At optimized differential pulse voltammetric parameters, the current response of NIF and ATN was proportionally linear in the concentration range of 3.98–107 μmol L–1 and 1.99–47.2 μmol L–1, with detection limit of 0.612 and 0.999 μmol L−1, respectively. The proposed method was successfully applied in analysis of several commercial combined dosage forms, whose accuracy was attested by good agreement of the results (paired t test at a 95% confidence level) with those obtained using high performance liquid chromatography.

Carbon Nanomaterials in Electrochemical Detection

This chapter overviews the use of carbon nanomaterials in the field of electroanalysis and considers why carbon-based nanomaterials are widely utilized and explores the current diverse range that is available to the practising electrochemist, which spans from carbon nanotubes to carbon nanohorns through to the recent significant attention given to graphene.

Sensitive spectrophotometric determination of atenolol in pharmaceutical formulations using bromate-bromide mixture as an eco-friendly brominating agent

Three simple and sensitive spectrophotometric methods are proposed for the determination of atenolol (ATN) in bulk drug and tablets. The methods are based on the bromination of ATN by the bromine generated in situ by the action of the acid on the bromate-bromide mixture followed by the determination of unreacted bromine by reacting with a fixed amount of either meta-cresol purple (MCP) and measuring the absorbance at 540 nm (method A) and 445 nm (method B) or erioglaucine (EGC) and measuring the absorbance at 630 nm (method C). Beer's law is valid within the concentration ranges of 1.0-20.0, 2.0-40.0 and 1.0-8.0 μg/mL for method A, method B and method C, respectively. The calculated molar absorptivities were found to be 1.20×10(4), 4.51×10(3) and 3.46 × 10(4)  L/mol · cm for method A, method B and method C, respectively. Sandell's sensitivity values, correlation coefficients, limits of detection and quantification are also reported. Recovery results were statistically compared with those of a reference method by applying Student's t- and F-test. The novelty of the present study is the measurement of two different colors using MCP, that is, red-pink color of MCP in acid medium at 540 nm and yellowish-orange color of brominated MCP at 445 nm.

Determination of atenolol in pharmaceutical formulations by diffuse reflectance spectroscopy

A simple analytical method for quantification of atenolol in pharmaceutical formulations by diffuse reflectance spectroscopy is described. The method is based on the reaction, on the filter paper surface, between the drug and p-chloranil producing a colored compound. The best reaction conditions were obtained with 20 µL of atenolol solution and 20 µL of p-chloranil. All reflectance measurements were carried out at 550 nm and the linear range was from 1.13x10-2 to 7.88x10-2 mol L-1 (r = 0.9992). The limit of detection was 2.80 x 10-3 mol L-1. The proposed method was successfully applied to analysis of different commercial brands of pharmaceutical formulations and the results obtained by the proposed method were in good agreement with those obtained using the British Pharmacopoeia method.

Fullerene C60 modified gold electrode and nanogold modified indium tin oxide electrode for prednisolone determination

The electrochemical determination of prednisolone has been investigated at fullerene-C(60)-modified gold (C(60)/Au) electrode and gold nanoparticles modified indium tin oxide (nano Au/ITO) electrode in phosphate buffer solution (PBS) of pH 7.2. During oxidation of prednisolone, an anodic peak with peak potential (E(p)) at 570 mV and 400 mV appeared at nano Au/ITO and C(60)/Au electrode, respectively. The experimental results revealed that gold nanoparticles as well as fullerene (C(60)) promote the rate of prednisolone oxidation by increasing the peak current (i(p)) and oxidizing at lower peak potentials as compared to the respective bare electrodes due to their electrocatalytic effect. The linear concentration range at both the electrodes was in the range of 1 microM to 0.10 mM. The detection limit obtained at C(60)/Au electrode was 26 nM, while at nano Au/ITO electrode the detection limit was 90 nM. The applicability of the method to direct assays of human urine and whole blood sample is described to use the method for testing cases of doping by athletes.