Synthesis of a Novel [diresorcinate‐1,10‐phenanthrolinecobalt(II)] Complex, and Potentiodynamic Fabrication of Poly(DHRPCo)/GCE for Selective Square Wave Voltammetric Determination of Procaine Penicillin G in Pharmaceutical and Biological Fluid Samples

Novel electrochemical sensor based on poly([Cu(H2O)2P2]I2)/GCE for the determination of trimethoprim in clinical samples and cow's milk samples

A Novel bioanalytical detector based on Poly(Diaquabis(1,10-phenanthroline copper (II) Iodide) (poly([Cu(H2O)2P2]I2)/GCE) has been fabricated by potentiodynamic polymerization of [Cu(H2O)2P2]I2. The synthesized complex and the fabricated electrodes showed a promising electrocatalytic behavior towards the electrooxidation of Trimethoprim (TPM). Based on the regression coefficient value of scan rate with peak current and square root of peak current, the oxidation of TMP at poly([Cu(H2O)2P2]I2)/GCE was dominated by diffusion. Under the optimized experimental conditions and square wave voltammetric parameters, the poly([Cu(H2O)2P2]I2)/GCE revealed very wide responses in the range of concentration of 500 nM-160 μM with a limit of detection of 3.91 nM and a Limit of quantification of 13.02 nM with the relative standard deviation below 1.75 %. The valuable applicability of the fabricated sensor for the determination of TMP in real samples, including cow's milk, blood serum, and human urine, was successfully investigated. The electroanalysis results from the spike recovery and interference study provided an excellent range of recovery with an error percent of below 3.0 % in the combination effect with the potential interferents. The sensor exhibited excellent reproducibility, sensitivity, long-term stability, high accuracy, and fast response. The developed bioanalytical sensor revealed the best application prospect for biomedicine and environmental monitoring activities.

Simultaneous Determination of Sulfamethoxazole and Trimethoprim from Clinical Urine and Blood Serum Samples by the Application of Poly(Cu2P4BCL4)/GCE

Synthetic antibiotics known as sulfonamides suppress the synthesis of tetrahydrofolic acid, which cures respiratory tract infections and protozoal infections by preventing the creation of dihydrofolic acid. Electrochemical sensors based on tetrakis(1,10-phenanthroline)-μ-(4,4'-bipyridine) dicopper(II) chloride monohydrate ([P2Cu-Bip-CuP2]Cl4·H2O or simply Cu2P4BCl4) have been successfully applied for the determination of sulfamethoxazole (SMX) and trimethoprim (TMP) from samples. The experimental conditions and parameters were optimized to achieve the best electrode performances for simultaneous quantification of SMX and TMP. Based on the analysis of the effect of scan rate on the peak parameters, the R 2 for the peak current vs square root of the scan rate was greater than that of the peak current vs scan rate, indicating diffusion-controlled behavior of both species. The current intensities of both SMX and TMP were highly improved due to surface activation of the electrodes by electropolymerization. For SMX, the limit of detection was determined to be 27.94 nM, while for TMP, it was 21.56 nM, and the limit of quantifications was 71.88 nM, and the corresponding relative standard deviation for each was 0.74% and 0.11%. The constructed electrode was stored for varying durations ranging from two h to 2 days, and it was found to be above 97% stable after storing for 15 days. The real applicability of the suggested sensor for the simultaneous determination of SMX and TMP was verified by sensing clinical serum and urine samples and their spike recovery studies.

Innovative voltammetric techniques for bumadizone analysis in pharmaceutical and biological samples: emphasizing green, white, and blue analytical approaches

There are no documented electroanalytical methods for quantifying the anti-inflammatory drug bumadizone (BUM) in pharmaceutical or biological matrices. So, a new voltammetric method was developed to determine BUM at nano concentrations in pharmaceutical forms, in the presence of its alkaline degradant, and in biological fluids. Five electrodes were tested, including three nano-reduced graphene oxide (nRGO) electrodes (5%, 15%, and 20%), a carbon paste electrode (CPE), and a 10% nRGO-modified CPE. The 10% nRGO-modified electrode showed the best performance, offering high selectivity and low detection limits, with good linearity in the concentration range of 0.9 × 102 to 15 × 102 ng mL-1. Differential pulse voltammetry successfully applied this electrode for BUM determination in various samples, achieving excellent recovery without preliminary separation. The method was validated according to ICH guidelines and compared favorably to the reference method. Its environmental impact was assessed using AGREE and Eco-scale metrics in addition to the RGB algorithm, showing superior greenness and whiteness profiles due to safer solvents and lower energy consumption, along with high practical effectiveness using the BAGI metric.

Highly Specific Voltammetric Detection of Cephalexin in Tablet Formulations and Human Urine Samples Using a Poly(2,4,6-2',4',6'-hexanitrodiphenylamine)-Modified Glassy Carbon Electrode

β-Lactam antibiotics are employed to treat bacterial illnesses. Despite a high level of clinical success, they have encountered serious resistance that demands a high-dose regimen and a new pharmacokinetic combination. This requires continuous monitoring of their levels in pharmaceutical and biological samples. In this study, an electrochemical sensor was developed for the determination of cephalexin (CLN) in pharmaceutical formulations and biological fluid samples. The sensors were developed by modifying a glassy carbon electrode (GCE) using a conducting polymer (dipicrylamine) by potentiodynamic electropolymerization. Characterization (using cyclic voltammetry and electron impedance spectroscopy) results revealed modification of the electrode surface, leading to an enhanced effective electrode surface area and their conductivity. The appearance of an irreversible oxidative peak at much-reduced potential with 5-fold current enhancement at a poly(dipicrylamine)-modified glassy carbon electrode (poly(DPA)/GCE) verified the electrocatalytic role toward CLN. Under optimized conditions, a wider linear concentration range (5 × 10-8 to 3.0 × 10-4 M), lowest limit of detection (LoD) (2.5 nM), detected amount of each tablet brand above 97.00% of the labeled value (showing excellent agreement between the detected amount and company label), and excellent % recovery results in pharmaceutical and biological samples were obtained with an excellent interference recovery error of less than 4.05%. Its excellent accuracy, selectivity, reproducibility, and stabilities and only requiring a simple electrode modification step combined with its readily available and nontoxic modifier, which sets it apart from most previously reported methods, have validated the present method's potential applicability for determining CLN in biological and pharmaceutical samples.

Characterization and Application of a Synthesized Novel Poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II) chloride)-Modified Glassy Carbon Electrode for Selective Voltammetric Determination of Cefadroxil in Pharmaceutical Formulations, Human Urine, and Blood Serum Samples

Cefadroxil belongs to the β-lactam antibiotics, mainly used for the treatment of various bacterial infections, caused by Gram-positive and Gram-negative bacteria. However, it is also encountering serious bacterial resistance, necessitating continuous monitoring of its level in pharmaceutical and biological samples. This study presents a selective, accurate, and precise square-wave voltammetric method based on a novel poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II)chloride)-modified glassy carbon electrode (poly(CP₂RCoC)/GCE) for determination of cefadroxil (CDL). UV-vis spectroscopy, FT-IR spectroscopy, metal and halide estimation, CHN elemental analysis, and electrolytic conductivity measurement results confirmed the synthesis of the title complex modifier. Electrode characterization results revealed modification of the surface of the electrode by an electroactive and a conductive polymer film (poly(CP₂RCoC)/GCE), leading to an improved effective electrode surface area. In contrast to the bare electrode, the appearance of an irreversible oxidative peak at a much reduced potential with a 7-fold current enhancement at poly(CP₂RCoC)/GCE showed the catalytic effect of the modifier toward oxidation of CDL. The square-wave voltammetric current response of poly(CP₂RCoC)/GCE showed a linear dependence on the concentration of CDL in the range of 1 × 10^-7-3.0 × 10^-4 M with a detection limit of 4.3 × 10^-9. The CDL level in the selected two tablet brands was in the range of 97.25-100.00% of their labeled values. The spike recovery results in tablet, human blood serum, and urine samples were 98.85-101.30, 99.20-100.39, and 98.10-99.99%, respectively. Interference recovery results with a less than 4.74% error, lower LoD, and wider dynamic range than the previously reported methods validated the potential applicability of the present method with excellent accuracy and sensitivity based on the novel mixed-ligand complex-modified GCE (poly(CP₂RCoC)/GCE) for determination of CDL in various real samples with a complex matrix.

Electrochemical Determination of Chloroquine Phosphate in Real Samples Using a Diresorcinate-1,10-phenanthrolinecobalt(II)-Modified Glassy Carbon Electrode

Chloroquine phosphate (CQP) is used for malaria treatment. As it is facing increasing resistance, it needs continuous monitoring using sensitive and specific detection methods. In this work, a voltammetric sensor was prepared by electropolymerization of a diresorcinate-1,10-phenanthrolinecobalt(II) complex on a glassy carbon electrode (poly(DHRPCo)/GCE) which was followingly characterized. Compared with a bare GCE, CQP showed single well shaped irreversible oxidative peak at the poly(DHRPCo)/GCE. The peak current showed excellent linearity with CQP concentration in the range of 0.005-300.0 μm with a detection limit of 0.39 nm. The response of CQP at poly(DHRPCo)/GCE was not influenced by the presence of amoxicillin, ciprofloxacillin and paracetamol in addition to its high stability and reproducibility. It was applied for detection of CQP in various real samples, including three brands of tablets, human blood serum, and urine samples. The detected amount in tablets were in the range 98.4-103.2 % of their labeled value. Spike recovery results in human blood serum, urine, and tablet samples were 99.35-100.28 %, 99.03-100.32 %, and 98.40-100.41 %, respectively. Interference recovery results with less than 4.60 % error, the lower limit of detection and the wider dynamic range than most of the previously reported methods validate the potential applicability of the proposed method for CQP determination in various real samples with complex matrices.

Synthesis of a novel diaquabis(1,10-phenanthroline)copper(II)chloride complex and its voltammetric application for detection of amoxicillin in pharmaceutical and biological samples

A one step facile synthesis of the novel diaquabis(1,10-phenanthroline)copper(II)chloride (A₂P₂CuC) complex is demonstrated. Cyclic voltammetric and electrochemical impedance spectroscopic results revealed potentiodynamic deposition of a conductive electroactive poly(A₂P₂CuC) film on the glassy carbon electrode surface increasing its effective surface area. In contrast to the unmodified glassy carbon electrode, appearance of an oxidative peak at a reduced potential with over two fold current for amoxicillin at poly(A₂P₂CuC)/GCE demonstrated its electrocatalytic property attributed to reduce charge transfer resistance and the improved surface area of the electrode surface. Better correlation of the oxidative peak current with square root of scan rate (R² = 0.99779) than with scan rate (R² = 0.96953) supplemented by slope of 0.58 for log(current) versus log(scan rate) confirmed diffusion controlled irreversible oxidation of amoxicillin. At optimized solution and SWV parameters, current response of poly(A₂P₂CuC)/GCE showed linear dependence on concentration of amoxicillin (2.0–100.0 μM) with LoD 0.0115 μM. While no amoxicillin was detected in the human blood serum sample, an amount 89.40–100.55% of the nominal level was detected in the analyzed eight tablet brands. Spike recovery in tablet samples (98.90–101.95%) and blood serum sample (102.20–101.37%); interference with an error (%RSD) of 0.00–4.51% in tablet and 0.00–2.10% in serum samples; excellent stability and reproducible results, added with the wide dynamic range and low LoD validated the method for amoxicillin determination in pharmaceutical formulations and human urine samples.

Potentiodynamic Poly(resorcinol)-Modified Glassy Carbon Electrode as a Voltammetric Sensor for Determining Cephalexin and Cefadroxil Simultaneously in Pharmaceutical Formulation and Biological Fluid Samples

This study covers the development of a fast, selective, sensitive, and stable method for the simultaneous determination of cephalosporins (cephalexin (CLN) and cefadroxil (CFL)) in biological fluids and tablet samples using potentiodynamic fabrication of a poly(resorcinol)-modified glassy carbon electrode (poly(reso)/GCE). The results of cyclic voltammetry and electrochemical impedance spectroscopy supported the modification of the GCE by a polymer layer that raised the electrode surface area and conductivity. At the poly(reso)/GCE, an irreversible oxidative peak with four- and fivefold current enhancement for CLN and CFL, respectively, at a substantially lower potential demonstrated the catalytic action of the modifier. Under optimized solution and parameters, the peak current response at the poly(reso)/GCE revealed a linear dependence on the concentration of CLN and CFL within the range 0.1-300 and 0.5-300 μM, respectively, with a limit of detection (LoD) of 3.12 and 8.7 nM, respectively. The levels of CLN in four selected tablet brands and CFL in two tablet brands were in the vicinity of 91.00-103.65% and 97.7-98.83%, respectively, of their nominal values. The recovery results for CLN in pharmaceutical samples were in the range of 99.00-100.67% and for CFL 97.9-99.75% and for blood serum and urine samples 99.55-100.55% and 99.33-100.34% for CLN and 97.13-100.60% and 96.73-102.50% for CFL, respectively. Interference recovery results with errors less than 4.81%, lower LoD, wider dynamic range, excellent recovery results, and good stability of the modifier compared to those for the previously reported methods validated the use of the poly(reso)/GCE for determining CLN and CFL simultaneously in various real samples.