Development of sensitive spectrofluorometric approach based on formation of pyrrolidone derivative for determination of linagliptin through condensation reaction with ninhydrin and phenylacetaldehyde: Application to content uniformity and real plasma.

The new drug linagliptin belongs to the class of dipeptidyl peptidase-4 enzyme inhibitors. Linagliptin is used to treat type 2 diabetes and is taken orally either alone or in combination with other drugs. In this instance, a new, simple, and economical technique for analyzing linagliptin was developed by the effective use of a pyrrolidone derivative. The primary amine group of linagliptin permits its condensation with ninhydrin (0.14% w/v) to produce a fluorescent product in the presence of phenylacetaldehyde (0.02% v/v). All experimental parameters were carefully examined and adjusted in order to monitor the generation of the pyrrolidone derivative at excitation and emission wavelengths of 385 and 475 nm, respectively. The calibration graph was made by plotting the intensity of the fluorescence in relation to linagliptin concentration. A significant linearity was found for values ranging from 20 to 460 ng/mL. The process's validity has been verified by a thorough assessment of the instructions provided by the International Conference on Harmonization (ICH). The results indicate excellent uniformity with a reference method, showing that there is no substantial difference in precision and accuracy. The proposed approach was utilized for determining linagliptin in real rat plasma successfully owing to its high sensitivity. Additionally, the proposed approach was evaluated using the Eco-Scale evaluation tool and showed a high degree of eco-friendliness (86/100).

Zinc(II) complexation strategy for ultra-sensitive fluorimetric estimation of molnupiravir: Applications and greenness evaluation.

The endemicity of the pandemic coronavirus disease 2019 (COVID-19) infection proved to be transitional only. Spikes are forming again in 2023, and high expectations are returning for reinfections and viral mutations. Molnupiravir (MOL) has been approved as an oral antiviral drug for the treatment of the COVID-19 causative virion. Therefore, the development of an ultrasensitive, instantaneous, and cost-effective method for the quantification of MOL in real plasma samples and formulated dosage form are mandatory. The proposed approach is based on the synthesis of a MOL metal-chelation product. MOL as a ligand was chelated with 1.0 mM zinc(II) in an acetate buffer (pH 5.3). After illumination at 340 nm, the intensity of the MOL fluorescence measured at 386 nm was increased by about 10-fold. The linearity range was found to be from 60.0 to 800.0 ng mL-1 with limit of quantitation (LOQ) of 28.6 ng mL-1 . Two methods were utilized for measuring the greenness of the proposed method (Green Analytical Procedure Index [GAPI] and analytical greenness metric [AGREE] methods), with results equal to 0.8. The binding stoichiometry of MOL with the zinc(II) ion was found to be 2:1. All the experimental parameters were optimized and validated using International Conference on Harmonization (ICH) and United States Food and Drug Administration (US-FDA) recommendations. Furthermore, the fluorescent probes were successfully utilized in real human plasma with high percentages of recovery (95.6%-97.1%) without any matrix interferences. The mechanism of fluorescent complex formation was confirmed using 1 H NMR in the presence and absence of Zn(II). The method was further utilized for testing content uniformity of MOL in its marketed capsule dosage forms.

NiFe-based Prussian blue analogue nanopolygons hybridized with functionalized glyoxal polymer as a voltammetric platform for the determination of amisulpride in biological samples.

A novel voltammetric platform based on pencil graphite electrode (PGE) modification has been proposed, containing bimetallic (NiFe) Prussian blue analogue nanopolygons decorated with electro-polymerized glyoxal polymer nanocomposites (p-DPG NCs@NiFe PBA Ns/PGE). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) were utilized to investigate the electrochemical performance of the proposed sensor. The analytical response of p-DPG NCs@NiFe PBA Ns/PGE was evaluated through the quantity of amisulpride (AMS), one of the most common antipsychotic drugs. Under the optimized experimental and instrumental conditions, the method showed linearity over the range from 0.5 to 15 × 10-8 mol L-1 with a good correlation coefficient (R = 0.9995) and a low detection limit (LOD) reached, 1.5 nmol L-1, with excellent relative standard deviation for human plasma and urine samples. The interference effect of some potentially interfering substances was negligible, and the sensing platform demonstrated an outstanding reproducibility, stability, and reusability. As a first trial, the proposed electrode aimed to shed light on the AMS oxidation mechanism, where the oxidation mechanism was monitored and elucidated using the FTIR technique. It was also found that the prepared p-DPG NCs@NiFe PBA Ns/PGE platform had promising applications for the simultaneous determination of AMS in the presence of some co-administered COVID-19 drugs, which could be attributed to the large active surface area, and high conductivity of bimetallic nanopolygons.

An Innovative Polymer-Based Electrochemical Sensor Encrusted with Tb Nanoparticles for the Detection of Favipiravir: A Potential Antiviral Drug for the Treatment of COVID-19.

An innovative polymer-based electro-sensor decorated with Tb nanoparticles has been developed for the first time. The fabricated sensor was utilized for trace determination of favipiravir (FAV), a recently US FDA-approved antiviral drug for the treatment of COVID-19. Different techniques, including ultraviolet-visible spectrophotometry (UV-VIS), cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray Diffraction (XRD) and electrochemical impedance spectroscopy (EIS), were applied for the characterization of the developed electrode TbNPs@ poly m-THB/PGE. Various experimental variables, including pH, potential range, polymer concentration, number of cycles, scan rate and deposition time, were optimized. Moreover, different voltammetric parameters were examined and optimized. The presented SWV method showed linearity over the range of 10-150 × 10-9 M with a good correlation coefficient (R = 0.9994), and the detection limit (LOD) reached 3.1 × 10-9 M. The proposed method was applied for the quantification of FAV in tablet dosage forms and in human plasma without any interference from complex matrices, obtaining good % recovery results (98.58-101.93%).

Ultrasensitive green spectrofluorimetric approach for quantification of Hg(II) in environmental samples (water and fish samples) using cysteine@MnO2 dots.

Mercury (Hg2+ ) is a natural element present in foods such as fish, water and soil. Exposure to mercury leads to severe toxic effects on the nervous, digestive, and immune systems. Here, a novel, green, and environmentally friendly fluorescent probe decorated with cysteine/MnO2 quantum dots (Cys@MnO2 QDs) was synthesized. This synthesis was carried out using a simple ultrasound technique with the aid of cysteine for fabricating Cys@MnO2 QDs to estimate Hg levels in fish and water samples. In this morphological study, Cys@MnO2 QDs were fully characterized using high-resolution transmission electron microscopy, zeta potential analysis, fluorescence, ultraviolet-visible and infrared spectroscopy. The fluorescence of the synthesized Cys@MnO2 QDs was significantly quenched by gradually increasing the Hg(II) concentration. The quenching mechanism based on the Hg-S bonds strengthened the utility of the Cys@MnO2 QDs as a novel luminescent nanoprobe. The estimation of Hg was linear in the concentration range 0.7-100.0 ng mL-1 with a limit of quantitation equal to 0.30 ng mL-1 . The Cys@MnO2 QDs are fluorescent probes with various benefits such as speed, ease of use, cost- effective, and being environmentally friendly; they are easily applied in food manufacturing and for public health improvement.

Emphasis on the incorporation of Tropaeolin OO dye and silver nanoparticles for voltammetric estimation of flibanserin in bulk form, tablets and human plasma.

A novel electrochemical sensor based on the electro-deposition of silver nanoparticles (AgNPs) on Tropaeolin OO (poly-TO) layers over pencil graphite electrode (PGE) surface was fabricated for the first time for voltammetric determination of flibanserin (FBS); a drug enhances female sexual performance. Further characterization studies using cyclic voltammetry (CV), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were conducted. The AgNPs synergistic effect on poly-TO layers facilitates the FBS electro-oxidation in phosphate buffer solution (pH 6.0) and its determination in bulk form, tablets and in human plasma. Following ICH guidelines, validation of the proposed SWV method for FBS analysis was successfully achieved using the fabricated sensor (AgNPs@poly-TO/PGE). Under the optimal instrumental and experimental conditions, the anodic oxidation peak current was directly proportional to FBS concentration in the range from 0.1 to 8.5 µmol L-1 with low detection and quantitation limits (0.0286 and 0.0867 µmol L-1, respectively). High sensitivity, selectivity as well as easiness of fabrication are the main advantages of the modified sensor.

A bio-analytically validated HPLC-UV method for simultaneous determination of doripenem and ertapenem in pharmaceutical dosage forms and human plasma: a dual carbapenem regimen for treatment of drug-resistant strain of Klebsiella pneumoniae.

The emergence of strains resistant to certain antibiotics is turning into an important issue worldwide that threatens global health with the increasing incidence of carbapenemase-producing Klebsiella pneumoniae (KPC). Thus, successful doripenem-ertapenem (DOR-ERTA) combination is highly recommended in treatment of bacteremic ventilator-associated pneumonia due to Klebsiella pneumoniae. Hence, a fast and highly-sensitive HPLC-UV method was developed for the estimation of the cited drugs simultaneously in their pure form, pharmaceutical dosage forms and in simulated synthetic mixtures. The DOR-ERTA mixture was successfully separated within 6 min on a reversed-phase ODS column using an isocratic elution; a mobile phase mixture consists of 0.05 M phosphate buffer (pH 3.0 adjusted by 85% ortho-phosphoric acid) : acetonitrile : methanol (86 : 12 : 2; % v/v/v). The proposed method was optimized and validated according to ICH guidelines, where the calibration graph was constructed from 0.04 to 50 µg mL-1 and from 0.05 to 50 µg mL-1 with low detection limits reached 1.7 and 1.4 ng mL-1 for DOR and ERTA respectively. The proposed method showed higher sensitivity than several previous methods, which allowed an effective estimation of the DOR and ERTA in human plasma after a simple extraction method with high recovery results ranged from 96.30% ± 1.55 to 97.90% ± 1.45 and without any interference from plasma components.

A selective and highly sensitive high performance liquid chromatography with fluorescence derivatization approach based on Sonogashira coupling reaction for determination of ethinyl estradiol in river water samples.

A selective and highly sensitive high performance liquid chromatography (HPLC) with fluorescence derivatization method was developed for determination of ethinyl estradiol (EE); one of endocrine-disrupting compounds (EDCs). The fluorescence derivatization procedure was based on Sonogashira coupling reaction using 4-(4, 5-diphenyl-1H-imidazole-2-yl) iodobenzene (DIB-I), a fluorescence labeling reagent, to derivatize EE in presence of copper and palladium ions. The formed fluorescent product was separated on Cosmosil 5C18 MS-II by an isocratic elution with a mobile phase composed of acetonitrile: 5.0 mM Tris-HNO3 buffer, pH 7.4 (60:40, v/v %). The detection wavelengths were set at 310 and 400 nm as excitation and emission wavelengths, respectively. Various parameters affecting derivatization reaction were optimized. Further, the proposed method was validated and a good linearity with low detection limit (S/N=3) 7.4 ng L-1 was obtained in water sample after a simple solid-phase disk extraction (C18 SPE disk) method. The proposed method was successfully applied for detection of EE in river water samples in order to monitor EE concentration and to distinguish its effect on the ecosystem and human health.

Applicability of ninhydrin as a fluorescent reagent for estimation of teicoplanin in human plasma using salting-out assisted liquid-liquid extraction technique.

The applicability of ninhydrin, a widely used derivatizing reagent, for determination of teicoplanin (TEIC) in its pure form, pharmaceutical vials, and in human plasma was investigated. The presented spectrofluorimetric method was based on a condensation reaction between ninhydrin and the primary amine group existing in TEIC (in the presence of phenylacetaldehyde) to produce a highly fluorescent product detected at 460 nm (λex ,390 nm). Calibration plots were constructed in the concentration range 60-600 ng mL-1 with a good correlation coefficient of 0.9998 and a low detection limit of 10.84 ng mL-1 . The method was subjected to a bioanalytical validation study according to US-FDA recommendations. The proposed method was applied for analysis of TEIC in commercial vials with high recovery result 101.88 ± 1.11%. In addition, the method was utilized efficiently for detection of TEIC in human plasma using salting-out assisted liquid-liquid extraction technique (SALLE) with a recovery range from 96.71 ± 1.08% to 97.71 ± 0.86%. SALLE is an effective approach used for extraction of TEIC from human plasma without interferences using ammonium sulphate. The proposed method is highly recommended to monitor TEIC in clinical laboratory samples and therapeutic drug monitoring systems.

Development of HPLC method for estimation of glyoxylic acid after pre-column fluorescence derivatization approach based on thiazine derivative formation: A new application in healthy and cardiovascular patients' sera.

Glyoxylic acid (GA) is the intermediate metabolite in various mammalian metabolic pathways. GA showed high reactivity towards formation of advanced glycation end-products (AGEs); the main cause of pathogenesis and complications of many diseases. The presented study aimed to detect GA in healthy and cardiovascular patients' (CV) sera; however analysis of GA in biological fluid is a challenge and requires chemical derivatization. Hence, a new, highly sensitive, time saving and reproducible pre-column fluorescence derivatization procedure coupled with high performance liquid chromatography (HPLC) method was developed. The derivatization method was based on reaction of 2-aminobenzenthiol (2-ABT), a fluorogenic reagent, with GA in acidic medium to form highly fluorescent thiazine derivative (290 and 390 nm for excitation and emission wavelengths respectively). The fluorescent derivative was separated within 6 min on a reversed-phase ODS column using an isocratic elution with a mixture of methanol-water (70:30, v/v%). The proposed method parameters were optimized and the method was validated. A good linearity in the concentration range (0.05-5.0 µM) was obtained with detection limit (LOD) of 10 nM (200 fmol/injection), which is more sensitive than several previous methods. Moreover, the recovery results were within the range of 85.0-95.5 % and the intra- and inter-day precision results were ≤3.5%. It should be emphasized that this method is the first one for monitoring of GA in CV patients; to investigate its role for diagnosis and monitoring the severity and complications of this disease in clinical laboratory.

Highly sensitive cadmium sulphide quantum dots as a fluorescent probe for estimation of doripenem in real human plasma: application to pharmacokinetic study.

Thioglycolic acid-capped cadmium sulphide quantum dots (TGA-CdS QDs) have been synthesized and utilized as a fluorescent probe for the estimation of doripenem (DOR). Monitoring of DOR in different biological fluids is required to estimate the efficient dose to avoid bacterial infections and resistance. The investigated method is based on the measurement of fluorescence quenching of TGA-CdS QDs after the addition of DOR. The synthesized TGA-CdS QDs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) and ZETA sizer. The TGA-CdS QDs showed unique photophysical properties with high quantum yield (0.32) using a comparison method with rhodamine B. Different experimental parameters affecting the synthesis process of the TGA-CdS QDs and their behavior with the studied drug DOR were examined and optimized. The values of the fluorescence quenching were linearly correlated to DOR concentration over the range of 10-500 ng mL-1 with a good correlation coefficient of 0.9991. The proposed method showed higher sensitivity over several reported methods, with LOD reaching 2.0 ng mL-1. The method was effectively applied for the estimation of DOR in human plasma and urine with good recovery results ranged from 95.16% to 99.51%. Furthermore, the stability of DOR in the human plasma was studied and a pharmacokinetic study of DOR in real human plasma was conducted.

Modification of N,S co-doped graphene quantum dots with p-aminothiophenol-functionalized gold nanoparticles for molecular imprint-based voltammetric determination of the antiviral drug sofosbuvir.

A molecularly imprinted polymer (MIP) was developed for the electrochemical determination of the antiviral drug sofosbuvir (SOF). The MIP was obtained by polymerization of p-aminothiophenol (p-ATP) on N,S co-doped graphene quantum dots (N,S@GQDs) in the presence of gold nanoparticles to form gold-sulfur covalent network. The presence of quantum dots improves the electron transfer rate, enhances surface activity and amplifies the signal. The nanocomposites were characterized by FTIR, TEM, EDX, and SEM. The electrochemical performance of the electrode was investigated by differential pulse voltammetry and cyclic voltammetry. The sensor uses hexacyanoferrate as the redox probe and is best operated at a potential of around 0.36 V vs. Ag/AgCl. It has a linear response over the concentration range of 1-400 nM SOF, with a detection limit of 0.36 nM. Other features include high selectivity, good reproducibility and temporal stability. The sensor was applied to the determination of SOF in spiked human plasma. Graphical abstract Novel sofosbuvir imprinted p-ATP polymer was synthesized by the aid of gold nanoparticles on N,S co-doped graphene quantum dots as a good conductive support. The imprinted polymer was used for detection of sofosbuvir in real samples by using the ferri/ferrocyanide redox probe.

Development of sensitive benzofurazan-based spectrometric methods for analysis of spectinomycin in vials and human biological samples.

Spectinomycin hydrochloride (SPEC) is an aminoglycoside antibiotic that has a broad spectrum against several bacterial strains of humans and veterinary infections. However, SPEC lacks a fluorophore or chromophore and this lack makes its analysis a challenge. Our study provides a simple, sensitive and low-cost spectrofluorimetric/spectrophotometric method based on the reaction between secondary amine groups and a benzofurazan reagent using borate buffer (pH 9.2). The yielding compound was measured fluorimetrically at 530 nm (excitation at 460 nm) with colorimetry at 410 nm. The calibration curves ranged from 30 to 400 ng ml-1 and from 0.2 to 6 µg ml-1 for spectrofluorimetric and spectrophotometric analyses, respectively. The limits of detection were calculated to be 4.15 ng ml-1 and 0.05 µg ml-1 for spectrofluorimetric and spectrophotometric processes, respectively. The ultra-affectability and high selectivity of the proposed method permitted analysis of SPEC in the dosage form and in human plasma samples, with good recoveries of about 101.19 and 97.11%, respectively, without any matrix interference. The proposed strategy was validated using International Conference on Harmonization standards and validated bioanalytically using USFDA recommendations.

Highly sensitive UHPLC-DAD method for simultaneous determination of two synergistically acting antiepileptic drugs; levetiracetam and lacosamide: Application to pharmaceutical tablets and human urine.

A simple and highly sensitive ultra-high-performance liquid chromatographic-diode array (UHPLC-DAD) detection method was developed and validated for the simultaneous estimation of levetiracetam (LEV) and lacosamide (LAC). It was clinically proven that the combination of LEV and LAC exhibits a synergistic effect against refractory seizures in mice, which was the motivation for the analysis of this binary mixture both in bulk and in human urine samples. The binary mixture was resolved on a Hypersil BDS C18 analytical column, utilizing a mobile phase of 0.050 mol L-1 phosphate buffer (pH 5.60), methanol and acetonitrile in the ratio (80:10:10 v/v/v) using catechol as an internal standard. The mobile phase was pumped at a flow rate of 1.2 mL min-1 with diode array detection at 205 nm for both drugs and 270 nm for IS. Calibration curves were linear with correlation coefficient >0.9990 over the studied concentration range of 0.1-70.0 µg mL-1 for both drugs. The developed method was reproducible with low relative standard deviation values for intra- and inter-day precision (<2.0%). Both drugs were determined in bulk, pharmaceutical formulations and human urine samples without any interference from complex matrices.

Utility of the fluorogenic characters of benzofurazan for analysis of tigecycline using spectrometric technique; application to pharmacokinetic study, urine and pharmaceutical formulations.

Tigecycline (TIGE) is the newest tetracycline derivative antibiotic with low toxicity, it is used for management of infectious diseases caused by Gram-positive and Gram-negative bacteria. Hence, an efficient, selective and sensitive method was developed for analysis of TIGE in commercial formulations, human plasma and urine. The spectrofluorimetric technique based on the reaction of secondary amine moiety in TIGE with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in slightly alkaline medium producing a highly fluorescent product measured at 540 nm (λex at 470 nm) after heating for 15 min at 75°C. The proposed strategy was upgraded and approved by ICH rules and bio-analytical validated using US-FDA recommendations. A linear relationship between fluorescence intensity and TIGE concentration was observed over the concentration range 40-500 ng mL-1 with limit of quantification (LOQ) 21.09 ng mL-1 and limit of detection (LOD) 6.96 ng mL-1 .The ultra-affectability and high selectivity of the proposed strategy permits analysis of TIGE in dosage form, human plasma and urine samples with good recovery ranged from 97.23% to 98.72% and from 99.36% to 99.80% respectively, without any interfering from matrix components. Also, the developed strategy was used to examine the stability of TIGE in human plasma and applied for pharmacokinetic investigation of TIGE.

In situ polymerization and FT-IR characterization of poly-glycine on pencil graphite electrode for sensitive determination of anti-emetic drug, granisetron in injections and human plasma.

In situ polymerization is a simple and efficient technique for modification and fabrication of modified electrodes in voltammetry. An efficient and highly sensitive square wave voltammetric (SWV) method was developed for analysis of a 5-HT3 antagonist granisetron (GRN) using in situ polymerized glycine on pencil graphite electrode surface. It was found that the fabricated polymer enhanced the sensitivity by more than two times and enhanced the surface activity by more than three times. Surface area measurements showed that poly-Gly/PGE have large surface area of 44.3 mm2, when compared to that of bare PEG (12.1 mm2). Several methods as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) techniques were used to characterize the modified surface. Further, FT-IR spectroscopic study was used to predict the way of glycine polymerization on electrode surface and the possible interaction mechanism with GRN. After optimization, the proposed method showed a linear response of GRN concentrations in the range from 0.08 to 3.00 µmol L-1 with a limit of detection (LOD) of 26.2 nmol L-1 (9.14 ng mL-1). The method was utilized for GRN determination in ampoules and in real human plasma samples.

A comparative study of different electrodeposited NiCo2O4 microspheres anchored on a reduced graphene oxide platform: electrochemical sensor for anti-depressant drug venlafaxine.

Two different fabrication methods were performed and compared for preparation of binary metallic oxide microstructures supported on a reduced graphene oxide (rGO) modified graphite electrode. Nickel-Cobalt oxide microspheres (NiCo2O4 MSs) were prepared by two different deposition methods: wet chemical and in situ-electrical deposited methods. Different characterization methods were conducted, including cyclic voltammetry (CV), scanning emission microscopy (SEM), electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The deposition methods of NiCo2O4 MSs were found to affect the electrochemical behavior of the modified electrodes towards the oxidation of venlafaxine (VEN), an anti-depressant drug. The fabricated electrode showed linearity over the range 5-500 nmol L-1 and an excellent sensitivity with a limit of detection (LOD) and limit of quantitation (LOQ) of 3.4 and 10.3 nmol L-1, respectively. It was revealed that the wet-NiCo2O4@rGO modified electrode prepared by the wet chemical method showed an improved electrochemical behavior for determination of VEN in pharmaceuticals and human plasma with high recovery results in the range of 96.7-98.6% and 96.0-100.7%, respectively without any interference from the co-existing components.

Micelle and inclusion complex enhanced spectrofluorimetric methods for determination of Retigabine: Application in pharmaceutical and biological analysis.

Two new, simple, selective, and highly sensitive spectrofluorimetric methods were developed and validated for the determination of the antiepileptic drug; retigabine (RTG). The first method (Method-I) depends on enhancement of the weak native fluorescence of RTG via the use of an organized medium; sodium dodecyl sulphate (SDS) in acetate buffer (pH 3.74). The second method (Method-II) depends on the enhancement of RTG weak native fluorescence through complexation with a macromolecule; beta cyclodextrin (ß-CD) in phosphate buffer (pH 3.20). A full study of different experimental parameters influencing the fluorescence intensity was carried out. In addition, a thorough investigation of the fluorescence quantum yield, fluorophore brightness and mechanism of fluorescence enhancement was performed. A seven-fold improvement in the fluorescence intensity was brought by the first method, whereas a six and half-fold enhancement of the fluorescence intensity was obtained by the second one. Linearity was achieved over wide ranges (0.05-12.5 µg mL-1) and (0.05-15 µg mL-1) with low limits of detection (LOD) of 10.6 and 14.3 ng mL-1, and limits of quantification (LOQ) of 32.0 and 43.2 ng mL-1 for (Method-I) and (Method-II), respectively. The proposed methods were validated according to ICH and US-FDA guidelines. The applicability of the proposed methods was tested for determination of RTG in its pharmaceutical dosage forms, and to study the stability of RTG under different stress conditions according to ICH guidelines including alkaline, acidic, oxidative, thermal, and photolytic stress conditions. Moreover, the high sensitivity achieved by the proposed methods permitted the determination and detection of RTG in both spiked and real rabbit plasma samples utilizing a simple protein precipitation step followed by liquid-liquid extraction method. Percentage recoveries from rabbit plasma samples were within the acceptable limits; (93.47-104.74%) and (91.33-105.70%) for (Method-I) and (Method-II), respectively.

Enhancement effect of reduced graphene oxide and silver nanocomposite supported on poly brilliant blue platform for ultra-trace voltammetric analysis of rosuvastatin in tablets and human plasma.

The enhancement effect of reduced graphene oxide (rGO) combined with silver nanocomposite supported on poly brilliant blue (PBB) platform was investigated for ultra-trace analysis of rosuvastatin (RS). Herein, in situ electrochemical deposition of the silver nanoparticles (AgNPs) and rGO hybrid was performed on the surface of the polymerized brilliant blue (PBB) platform. The developed (AgNPs-rGO/PBB) electrode showed an enhanced catalytic activity toward the oxidation of RS. The modified electrodes AgNPs-rGO/PBB and AgNPs/PBB required an overpotential of 0.68 and 1.06 V to achieve a current density of 10 mA cm-2, and their corresponding Tafel slopes were calculated to be 70 and 105 mV dec-1, respectively. Further, rGO and silver nanocomposites properties were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), square wave voltammetry (SWV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). Additionally, the formation of GO and AgNPs-rGO was confirmed by Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Under the optimized conditions, the electrochemical sensor showed a remarkable response for quantitation of RS over a wide range of concentrations 5 × 10-9 to 5 × 10-7 mol L-1 (r = 0.9988), with a limit of detection 2.17 × 10-9 mol L-1. The electrochemical performance of the studied electrode showed high reproducibility and suitability for tablets and human plasma.