Evaluation of analytical greenness metric for an eco-friendly method developed through the integration of green chemistry and quality-by-design for the simultaneous determination of Nebivolol hydrochloride, Telmisartan, Valsartan, and Amlodipine besylate.

In recent years, the field of analytical chemistry has witnessed a notable shift towards the adoption of greener chromatographic methods, aiming to minimize the environmental impact. An effective strategy involves substituting conventional harmful organic solvents with environmentally friendly alternatives, reducing the use of hazardous chemicals that contribute to environmental concerns. However, separating drug substances without the use of buffers and organic solvents presence is a big challenge. To overcome this challenge, a combination of quality-by-design (QbD) and green analytical chemistry (GAC) was employed in this study for method development. A high-performance liquid chromatography (HPLC) method was successfully developed and validated for the simultaneous determination of Nebivolol hydrochloride, Telmisartan, Valsartan, and Amlodipine besylate. The method utilized a mobile phase composed of a mixture of 0.1 % formic acid in water (pH: 2.5) and ethanol. A regular octadecyl silica (ODS) column was employed, and UV detection at 220 nm was utilized. The method exhibited linearity within the concentration range of 25-75 µg/mL for Telmisartan and 150-450 µg/mL for Nebivolol Hydrochloride, Valsartan, and Amlodipine besylate and the correlation coefficient was greater than 0.999 for all the analytes. Limits of detection (LOD) and quantification (LOQ) were determined as 0.01 and 0.04 µg/mL for Telmisartan, 0.06 and 0.20 µg/mL for Nebivolol Hydrochloride, 0.08 and 0.25 µg/mL for Amlodipine besylate, and 0.14 and 0.46 µg/mL for Valsartan, respectively. The developed method underwent thorough validation, encompassing various parameters such as linearity, accuracy, precision, LOD, LOQ, robustness, and ruggedness. The mean recovery values were observed to range between 98.86 % and 99.89 %. The accuracy demonstrated was consistently above 98.98 % for both intra-day and inter-day precisions were with the relative standard deviations less than 2 %. To establish its robustness, a quality-by-design-based experimental design (DoE) approach was implemented. Additionally, the method's environmental friendliness was evaluated using the Analytical Greenness metric (AGREE) an analytical eco scale, both confirming its alignment with sustainable practices and reduced ecological impact. The sustainability of the solvent used in the current study was evaluated by Green Solvents Selecting Tool (GSST) Further, the developed method greenness was evaluated with the green analytical tools such as Analytical method greenness score (AMGS) and using the recently released White Analytical Chemistry (WAC) using RGB assessment tool. By employing this greener approach to chromatography method, this study contributes to the ongoing efforts in analytical chemistry to promote sustainable practices and minimize the environmental footprint of analytical methods.

Using the AQbD Approach, Development and Validation of a Simple, Rapid Stability Indicating Chromatographic Method for Quantification of Related Impurities of Apixaban.

Apixaban is a new oral anticoagulant that has been approved by the United States Food and Drug Administration for the prevention of stroke and other cardiovascular complications in people with non-valvular atrial fibrillation. Then, later, it was given the green light to treat deep venous thrombosis and pulmonary embolism. The biggest challenge in the development of pharmaceutical drugs is comprehending science- and risk-based techniques for developing and maintaining analytical procedures appropriate for evaluating the quality of drug substances and drug products. The improved technique provides a methodical strategy to acquire and improve understanding of an analytical method. The current study discusses the related substances method development for an apixaban drug substance employing a regulated authority refined and approved approach of the quality-by-design concept. For the quantification of impurities, and apixaban drug substance, a simple, quick and stability-indicating reverse-phase liquid chromatographic method was developed using a full factorial design. The separation between apixaban and its nine impurities was accomplished using an Zorbax Stable Bond Phenyl, 150 × 4.6 mm, 5 µm column. The mobile-phase components for gradient elution at a flow rate of 1.2 mL/min were chosen to be a mixture of water, acetonitrile, methanol and perchloric acid in various ratios with a total run time of 15 min. Chromatograms were extracted at 278 nm after a 5 µL solution injection. According to regulatory requirements, the developed method has been validated for its intended purpose.

Ferrocene tagged primary antibody generates electrochemical signal: An electrochemical immunosensing platform for the monitoring of vitamin D deficiency in clinical samples.

In this paper, a new kind of ultrasensitive and low-cost electrochemical immunosensing probe was designed to monitor vitamin D deficiency using 25(OH)D3 as a clinical biomarker. Ferrocene carbaldehyde conjugated on Ab-25(OH)D3 antibodies was used as an electrochemical probe for generating signals. The graphene nanoribbon-modified electrode (GNRs) was used to immobilize the (Ab-25(OH)D3-Fc) conjugate. The high electron transferability, greater surface area, and effective biocompatibility of GNRs enabled the capture of the greater number of primary antibodies (Ab-25(OH)D3). The developed probe was structurally and morphologically characterized. The step-wise modification was investigated by electrochemical techniques. The direct electrochemistry of ferrocene enabled 25(OH)D3 biomarker detection with excellent sensitivity. The reduction in peak current was proportional to the concentrations of 25(OH)D3 in the range of 1-100 ng mL-1 with a 0.1 ng mL-1 limit of detection. The probe was tested in terms of reproducibility, repeatability, and stability. Finally, the developed immunosensing probe was applied in serum samples for 25(OH)D3 quantification, and no significant difference was noticed in the assay results when compared with the standard chemiluminescent immunoassay (CLIA) method. The developed detection strategy has a wider scope for future potential clinical diagnostics applications.

Fabrication of electrochemical immunosensor based on GCN-ß-CD/Au nanocomposite for the monitoring of vitamin D deficiency.

Serum 25-hydroxyvitamin D (25(OH)D) has been clinically considered as a novel biomarker for vitamin D deficiency. The current standard technologies for the detection of 25(OH)D are performed in sophisticated laboratories exhibiting the practical limitations for onsite and affordable testing. Therefore, the development of a cost-effective device for Vitamin D is extremely necessary to provide an earlier diagnosis. Herein, for the first time, we propose a novel label-free impedimetric immunosensor for the detection and quantification of 25-hydroxyvitamin D3 (25(OH)D3) biomarker in serum samples based on the Au nanoparticles functionalized GCN-ß-CD nanocomposite. To fabricate the sensing probe, Ab-25(OH)D3 antibodies were covalently immobilized on GCN-ß-CD@Au/GCE using carbodiimide chemistry. The surface morphology and structural properties of constructed immunosensor were confirmed by different analytical techniques. Electrochemical impedance spectroscopy technique (EIS) has been selected as the main detection method to measure the Antibody (Ab) and Antigen (Ag) interaction at the immunosensor surface because it is label-free, less destructive to the activities of the biomolecule, and highly sensitive. The as-prepared immunosensor exhibited an excellent concentration range from 0.1 ng/ml to 500 ng/ml with the lowest limit of detection of 0.01 ng/ml. Furthermore, the sensing probe was validated in serum samples and obtained results were compared with the standard CLIA technique. The results have revealed that the sensing probe could be used for clinical diagnosis of Vitamin D deficiency in the clinical laboratories.

Development of an electrochemical immunosensor based on gold nanoparticles incorporated chitosan biopolymer nanocomposite film for the detection of prostate cancer using PSA as biomarker.

In this study, we have developed an electrochemical immunosensor for the detection of prostate-specific antigen (PSA) based on gold nanoparticles (AuNPs) and a chitosan (CHI) nanocomposite film coated on a screen printed electrode (SPE). The modified SPE was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The immunosensor was fabricated by sequential immobilization of anti-PSA primary antibody, PSA antigen and HRP-tagged secondary antibody on the surface of AuNPs/CHI/SPE. When this immunosensor was placed in 2.5mM H2O2, as HRP substrate, and 1mM methylene blue (MB), as redox mediator, greatly amplified immunosensing signals were observed. Immunosensing signals for the reduction of H2O2 were monitored in phosphate buffer (pH 7.0) by CV and square wave voltammetry (SWV). Under optimized conditions steady state current increased linearly with PSA concentration over the range 1-18ng/ml with a detection limit of 0.001ng/ml. The fabricated immunosensor demonstrated excellent sensitivity, stability and reproducibility and therefore was successfully applied to analyse PSA in biological samples. Finally, the results indicate that the proposed immunosensor has potential in clinical screening of cancer biomarkers.

Fabrication of highly sensitive and selective nanocomposite film based on CuNPs/fullerene-C60/MWCNTs: An electrochemical nanosensor for trace recognition of paracetamol.

Designing an electrochemical sensor for versatile clinical applications is a sophisticated task and how dedicatedly functionalized composite materials can perform on this stage is a challenge for today and tomorrow's Nanoscience and Nanotechnology. In the present work, we demonstrate a new strategy for the development of novel electrochemical sensor based on catalytic nanocomposite film. Fullerene-C60 and multi-walled carbon nanotubes (MWCNTs) were dropped on the pre-treated carbon paste electrode (CPE) and copper nanoparticles (CuNPs) electrochemically deposited on the modified CPE to form nanocomposite film of CuNPs/C60/MWCNTs/CPE. In this work, an electrochemical method based on square wave voltammetry (SWV) employing CuNPs/C60/MWCNTs/CPE has been presented for the recognition and determination of paracetamol (PT). Developed electrochemical sensor was characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronocoulometry. The composite film made the fabricated sensor to display high sensitivity and good selectivity for PT detection. The influence of the optimization parameters such as pH, accumulation time, deposition potential, scan rate and effect of loading of composite mixture of C60-MWCNTs and CuNPs on the electrochemical performance of the sensor were evaluated. A linear range from 4.0 × 10(-9) to 4.0 × 10(-7) M for PT detection was obtained with a detection limit of 7.3 × 10(-11) M. The fabricated sensor was successfully applied to the detection of PT in biological samples with good recovery ranging from 99.21 to 103%.

Fullerene-C60-MWCNT composite film based ultrasensitive electrochemical sensing platform for the trace analysis of pyruvic acid in biological fluids.

We propose development of a novel electrochemical sensor based on fullerene-multi-walled carbon nanotubes composite film for the sensitive determination of the pyruvic acid in biological fluids. The developed sensor was characterized by cyclic voltammetry. The nanocomposite film of C60-MWCNTs on GCE exhibits electrocatalytic activity towards pyruvic acid reduction and also decreases the reduction overpotential. The influence of the optimization parameters such as pH and effect of loading of composite mixture of C60 and MWCNTs on the electrochemical performance of the sensor were evaluated. Various kinetic parameters such as electron transfer number (n=2), proton transfer number (m=2) and charge transfer coefficient (α=0.56) were also calculated. Under optimized conditions, the squarewave reduction peak current was linear over the concentration range of 2.0-55 nM with the detection and quantification limit of 0.1 nM and 0.8 nM respectively. The fabricated sensor was successfully applied to the detection of pyruvic acid in biological samples with good recovery ranging from 97.6% to 103.6%.

Electrochemical determination of atropine at multi-wall carbon nanotube electrode based on the enhancement effect of sodium dodecyl benzene sulfonate.

Herein, a new electrochemical method was described for the determination of atropine based on the enhancement effect of an anionic surfactant: sodium dodecyl benzene sulfonate (SDBS). In pH 10.5 tetramethyl ammonium hydroxide as supporting electrolyte and in the presence of 0.4×10(-4)M SDBS, atropine yields a well-defined and sensitive oxidation peak at the multi-wall carbon nanotube electrode (MWCNTE). Compared with that in the absence of SDBS, the oxidation peak current of atropine remarkably increases in the presence of SDBS. The experimental parameters, such as supporting electrolyte, concentration of SDBS, and accumulation time, were optimized for atropine determination. The oxidation peak current is proportional to the concentration of atropine over the range from 3.98 ng/ml to 27.23 ng/ml. The detection limit is 0.449 ng/ml after 2 min of accumulation. This new voltammetric method was successfully used to determine atropine in Indian traditional medicine (seeds and leaves of Datura stramonium) with satisfactory recoveries. The developed method was also used for the analysis of atropine in pharmaceutical formulation of ophthalmic solution (eye drop). The relative standard deviations of intraday and interday analyses for atropine were 0.67% and 0.86% respectively (n=3) for the accumulation time of 120 s.

Electrochemical studies of quinine in surfactant media using hanging mercury drop electrode: a cyclic voltammetric study.

The electrochemical behavior of quinine was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) using surfactant. The reduction peak current of quinine increases remarkably in presence of 1% CTAB. Its electrochemical behavior is quasi-reversible in the Britton-Robinson buffers of pH 10.38 by exhibiting the well-defined single cathodic and anodic waves and the ratio of I(p)(a)/I(p)(c) approaching one at the scan rate of 500 mVs(-1). On the basis of CV, SWV and Coulometry, electrochemical reduction mechanism of quinine has been proposed which has shown that protonation occurs on the nitrogen of the quinoline moiety. Linearity was obtained when the peak currents (I(p)) were plotted against concentrations of quinine in the range of 30.0-230.0 ng mL(-1) with a detection limit of 0.132 ng mL(-1) in SWV and 90.0-630.0 ng mL(-1) with a detection limit of 0.238 ng mL(-1) in DPV. Fast and sensitive SWV has been applied for the quantitative analysis of quinine in bark of Cinchona sp. and in soft drinks and a good recovery was obtained. The accuracy and precision of the method are determined and validated statistically. No interferences from other food additives were observed. The relative standard deviation for intraday and interday assay was 0.89 and 0.73% (n=3) respectively.