Electrochemical Sensing of Favipiravir with an Innovative Water-Dispersible Molecularly Imprinted Polymer Based on the Bimetallic Metal-Organic Framework: Comparison of Morphological Effects

Molecularly imprinted polymers (MIPs) are widely used as modifiers in electrochemical sensors due to their high sensitivity and promise of inexpensive mass manufacturing. Here, we propose and demonstrate a novel MIP-sensor that can measure the electrochemical activity of favipiravir (FAV) as an antiviral drug, thereby enabling quantification of the concentration of FAV in biological and river water samples and in real-time. MOF nanoparticles’ application with various shapes to determine FAV at nanomolar concentrations was described. Two different MOF nanoparticle shapes (dodecahedron and sheets) were systematically compared to evaluate the electrochemical performance of FAV. After carefully examining two different morphologies of MIP-Co-Ni@MOF, the nanosheet form showed a higher performance and efficiency than the nanododecahedron. When MIP-Co/Ni@MOF-based and NIP-Co/Ni@MOF electrodes (nanosheets) were used instead, the minimum target concentrations detected were 7.5 × 10−11 (MIP-Co-Ni@MOF) and 8.17 × 10−9 M (NIP-Co-Ni@MOF), respectively. This is a significant improvement (>102), which is assigned to the large active surface area and high fraction of surface atoms, increasing the amount of greater analyte adsorption during binding. Therefore, water-dispersible MIP-Co-Ni@MOF nanosheets were successfully applied for trace-level determination of FAV in biological and water samples. Our findings seem to provide useful guidance in the molecularly imprinted polymer design of MOF-based materials to help establish quantitative rules in designing MOF-based sensors for point of care (POC) systems.

Simultaneous determination of hydrochlorothiazide, amlodipine, and telmisartan with spectrophotometric and HPLC green chemistry applications

For the quantifiable amounts of Telmisartan (TLM) and Hydrochlorothiazide (HYD) in the presence of Amlodipine (AML) in a ternary mixture of synthetic laboratory mixture, a novel, sensitive, quick, and practical reversed-phase high-performance liquid chromatography (RP-HPLC) method was given. In order to separate, a Waters Spherisorb ODS-2 C18 column was used. For HYD, TLM, and AML, these techniques were viable over linearity ranges of 4-12 μg/mL, 4-25 μg/mL, and 5-40 μg/mL, respectively. The mobile phase system was acetonitrile:methanol: phosphate buffer at pH 2.5 (65:5:30 v/v/v), and the flow rate was 1.5 mL/min. Novel spectrophotometric methods were applied for active substances to determine simultaneously. The first method is absorptivity centering using factorized spectrum, and the second method is dual amplitude difference coupled with absorbance subtraction. These approaches have been effectively applied to bulk, laboratory synthetic mixtures to employ active components quantitatively. Correlation coefficients were found to be higher than 0.99 and the limit of detection values lower than 0.49 μg/mL in both spectrophotometric methods. The methodologies were validated following ICH recommendations. In the developed HPLC method, the limit of detection values was found to be 0.01 μg/mL for HYD and 0.02 μg/mL for AML and TLM. The correlation coefficients for the HPLC method were found to be 0.9971 for HYD, 0.9990 for AML, and 0.9983 for TLM. The suggested HPLC technique is a simple, effective, sensitive, environmentally friendly, and time-saving approach for determining TLM and HYD in the presence of AML.

Determination of active ingredients in antihypertensive drugs using a novel green HPLC method approach

A novel, sensitive, fast, and pratic RP-HPLC methods were presented for the quantitative amounts of Telmisartan (TEL) and Olmesartan (OLM) in the presence of Amlodipin (AML) in a binary mixture of pharmaceutical preparation. Waters Spherisorb ODS-2 C18 column was used for separation. These methods were valid over linearity ranges of 2.5-30 μμg/mlL, 2-85 μμg/mlL, and 2-35 μμg/mlL for OLM, TEL, and AML, respectively. The mobile phase system consisted of acetonitrile:methanol: phosphate buffer at pH 3.0 (65:5:30 v/v/v), and the flow rate was 1,5 mlL/min for OLM and AML. The mobile system's other mixture (TEL and AML) was acetonitrile:methanol: phosphate buffer at pH 2.5 (65:5:30 v/v/v), and the flow rate was 1,5 mlL/min. These procedures were successfully applied to bulk, laboratory synthetic mixture, and medicinal dosage forms to use active ingredients quantitatively. The studied methods were validated according to ICH guidelines. In the developed HPLC method, the limit of detection values was found to be 0.020 μμg/mlL for TEL, 0.025 μμg/mlL for OML, and 0.070 μμg/mlL for AML. The correlation coefficients for the HPLC method were found to be 0.9938 for TEL, 0.9996 for OML, and 0.9982 for AML. The calibration range is between 2.5 and -30, 5-35, and 2-85 μμg/mlL for OLM, AML, and TEL, respectively. The proposed HPLC method is a convenient, effective, sensitive, green, and time-saving method for the rapid determination of TEL and OLM in the presence of AML.

A reusable and sensitive electrochemical sensor for determination of idarubicin in environmental and biological samples based on NiFe2O4 nanospheres anchored N-doped graphene quantum dots composite; an electrochemical and molecular docking investigation

An ultrasensitive and selective voltammetric sensor with ultra-trace level detection limit is introduced for idarubicin (IDA) determination in real samples. The as-synthesized nanocomposite was characterized by several techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, Energy-dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscopy (FE-SEM). The electrocatalytic performance of the developed electrode was observed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The limit of detection (LOD) of the developed sensor for idarubicin is 1.0 nM, and the response is found to be in the dynamic concentration range of 0.01-1.9 μmol/L in a Britton-Robinson buffer (B-R, pH = 6.0). Moreover, the fabricated electrode illustrated high selectivity with good repeatability and reproducibility for diagnosing idarubicin as an anthracycline antileukemic drug. Furthermore, to evaluate the validity of the recommended method, three real samples, including human plasma, urine, and water samples, were analyzed with satisfactory recovery and compared with high-performance liquid chromatography (HPLC). The minor groove-binding mode of interaction was also supported by docking simulation studies, emphasizing that IDA can bind to ds-DNA preferably and confirmed experimental results. The reduced assay time and the possibility of measuring a single sample with another anticancer drug without any interference are significant advantages compared to the HPLC. The developed and validated sensor could be a valuable point-of-care diagnostic tool for IDA quantification in patients.

A zinc oxide nanorods/molybdenum disulfide nanosheets hybrid as a sensitive and reusable electrochemical sensor for determination of anti-retroviral agent indinavir

This work aims to develop an electrochemical sensor for the reusable and selective detection of trace levels of indinavir (IDV) as an anti-retroviral drug by using zinc oxide nano-rods/molybdenum disulfide nanosheets on a screen-printed electrode (ZnO NRs/MoS₂ NSs/SPE). Quantitative IDV detection was achieved using differential pulse voltammetry (DPV). The assay specificity was illustrated using interfering species and exhibited high specificity toward the IDV. The developed displayed a wide dynamic range, from 0.01 to 0.66 and 0.66-7.88 μM in Britton-Robinson (B-R) buffer, with a 0.007 μM limit of detection. The fabricated ZnO NRs/MoS₂ NSs/SPE electrode exhibited high sensitivity, stability, good reproducibility, and repeatability towards the sensing of IDV. It turned out that the hybrid electrochemical sensor's sensing performance was remarkably improved due to the synergistic effect between MoS₂ NSs and ZnO NRs, where the former affords a large active surface area and quick electron transfer. The reported sensor provides a new alternative for electrochemical detection of IDV and could expand the applications of metal nanoparticles in emerging technologies for monitoring drugs in real samples.

The power of High Impact Amplitude Manipulation (HIAM) technique for extracting the basic spectra of two Fixed-dose combinations (FDC) -Spectrophotometric purity analysis via spectral contrast angle

HIAM technique allows the extraction of the original constant signal of each single component out of interference signals of a mixture and further transformed into basic spectrum (D⁰). It includes the methods: ratio subtraction coupled with unified constant subtraction (RS-UCS), constant center (CC) and constant extraction (CE). The technique was introduced for the analysis of two pharmaceutical formulations used to treat cardiovascular diseases. The formulations are binary combinations of Amlodipine (AML) with either Atorvastatin (ATR) or Candesartan (CND) which shows interefernce absorbance signals. The technique was valid over the linearity range of (5.0-35.0 µg/ml) for AML, ATR and CND with recovery percentage 100.40 ± 1.88 , 100.00 ± 0.86 and 99.83 ± 1.07, respectively . The extracted signals were tested for its purity by spectral contrast angle (cos θ) to illustrate the efficency of the HIAM technique where cos θ values ranges from (0.9902 to 0.9986). The presented technique was fully validated regarding ICH guidelines and were statistically compared using one-way ANOVA at 95% confidence.

Cerium functionalized graphene nano-structures and their applications; A review

Graphene-based nanomaterials with remarkable properties, such as good biocompatibility, strong mechanical strength, and outstanding electrical conductivity, have dramatically shown excellent potential in various applications. Increasing surface area and porosity percentage, improvement of adsorption capacities, reduction of adsorption energy barrier, and also prevention of agglomeration of graphene layers are the main advantages of functionalized graphene nanocomposites. On the other hand, Cerium nanostructures with remarkable properties have received a great deal of attention in a wide range of fields; however, in some cases low conductivity limits their application in different applications. Therefore, the combination of cerium structures and graphene networks has been widely invesitaged to improve properties of the composite. In order to have a comprehensive information of these nanonetworks, this research reviews the recent developments in cerium functionalized graphene derivatives (graphene oxide (GO), reduced graphene oxide (RGO), and graphene quantum dot (GQD) and their industrial applications. The applications of functionalized graphene derivatives have also been successfully summarized. This systematic review study of graphene networks decorated with different structure of Cerium have potential to pave the way for scientific research not only in field of material science but also in fluorescent sensing, electrochemical sensing, supercapacitors, and catalyst as a new candidate.

An electrochemical molecularly imprinted sensor based on CuBi2O4/rGO@MoS2 nanocomposite and its utilization for highly selective and sensitive for linagliptin assay

The molecularly imprinted polymers (MIP) is an outstanding electrochemical tool that demonstrates good chemical sensitivity and stability. These main advantages, coupled with the material's vast microfabrication flexibility, make molecularly imprinted sensors an attractive sensing device. Herein, it was aimed to develop a state-of-art molecularly imprinted sensor based on CuBi₂O₄/rGO@MoS₂ nanocomposite to be utilized for the detection of linagliptin (LNG), a novel hypoglycemic drug. The electrochemical characterizations of linagliptin on the surface of the modified electrode was examined via cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Several characterization methods including transmission electron microscope (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Energy-dispersive X-ray spectroscopy(EDX), were utilized for electrode characterization. The LNG imprinted voltammetric sensor was developed in 80.0 mM phenol containing 20.0 mM LNG. CuBi₂O₄/rGO@MoS₂ nanocomposite on LNG imprinted screen-printed carbon electrode (SPCE) (MIP/CuBi₂O₄/rGO@MoS₂ nanocomposite/SCPE) exhibited a linear relationship between peak current and LNG concentration in the range 0.07-0.5 nM with a detection limit of 0.057 nM. In the existence of interfering substances, an LNG imprinted electrode was utilized to analyze urine, human plasma, and tablet samples with adequate selectivity. The developed sensor was also illustrated for stability, repeatability, reproducibility, and reusability.

Dual-response electrochemical electrode for sensitive monitoring of topotecan and mitomycin as anticancer drugs in real samples

This research paper employed an innovative electrochemical electrode to simultaneously determine topotecan (TPT) and mitomycin (MMC) as anticancer agents. For this purpose, a novel nanocomposite was synthesized using a hydrothermal procedure. The nanocomposites were characterized using FTIR, STEM, FESEM, mapping analysis, EDX, and XRD methods. The novelty of this work is the successful synthesis of Fe₃O₄ decorated on the surface of CuCo₂S₄ (Fe₃O₄@CuCo₂S₄) nanocomposites showed two separate anodic peaks at 0.8 V for TPT and 1.0 V for MMC with potential separation of 0.2 V. This was enough for the simultaneous electrochemical determination of topotecan and mitomycin on a glassy carbon electrode (GCE), simultaneously. At optimized conditions, the developed electrode exhibited linear responses with TPT and MMC concentration in the ranges of 0.01-0.89 and 0.89-8.95 μM for topotecan and 0.1-19.53 μM for mitomycin. The detection limits were observed as 6.94 nM and 80.00 nM for topotecan and mitomycin, respectively. The fabricated Fe₃O₄@CuCo₂S₄/GCE showed high sensitivity, long-term stability, and repeatability towards the sensing of TPT and MMC simultaneously and can be utilized in real samples. The obtained results confirmed that the fabricated Fe₃O₄@CuCo₂S₄/GCE nanocomposites can be utilize in the simultaneous electrochemical determination of topotecan and mitomycin in real samples.

A sensitive voltammetric sensor for specific recognition of vitamin C in human plasma based on MAPbI3 perovskite nanorods

A novel and sensitive electrode was suggested for the rapid determination of ascorbic acid (AA) using a glassy carbon electrode (GCE) modified with synthesized MAPbI3 and L-cys (L-cys/MAPbI3/GCE). Determination of ascorbic acid as an important component of the human diet due to help in decreasing blood pressure and improving endothelial function is crucial. The synthesized MAPbI3 was characterized by different methods, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The fabricated electrode exhibited superior electrical conductivity and fast electron transfer kinetics. The results illustrated that the developed electrode had an outstanding electrocatalytic activity towards the oxidation of AA in 0.1 M Britton–Robinson buffer(B-R) as a supporting electrolyte. The modified electrode demonstrated a linear range in differential pulse voltammetry of 0.02–11.4 µM with a low detection limit of 8.0 nM for ascorbic acid. It can be stated that the proposed sensor can be successfully applied to the determination of ascorbic acid in human plasma samples.

Electrochemical immunosensor for rapid and highly sensitive detection of SARS-CoV-2 antigen in the nasal sample

A label-free electrochemical biosensing approach as an appropriate analysis technique for SARS-CoV-2 spike protein (SARS-CoV-2 S-protein) was investigated to facilitate the diagnosis of coronavirus in real samples. It is crucial to construct diagnostic features that can rapidly identify infected individuals to limit the spread of the virus and assign treatment choices. Therefore, a novel and selective method using SiO₂@UiO-66 and a label-free electrochemical immunoassay for rapidly detecting spike protein. The development of innovative approaches for direct viral detection employing simplified and ideally reagent-free assays is a pressing and difficult topic. The absence of speedy and effective ways to diagnose viral diseases especially SARS-CoV-2 on demand has worsened the issue of combating the COVID-19 pandemic. The developed electrode illustrated a wide dynamic range of 100.0 fg mL⁻¹ to 10.0 ng mL⁻¹ with low limit detection. Therefore, the as-fabricated electrochemical SARS-CoV-2 S-protein sensor suggests an appropriate perspective in the point-of-care system, within 5.0 min, in nasal samples with satisfactory recovery.

Novel enzymatic graphene oxide based biosensor for the detection of glutathione in biological body fluids

In this work, we report a novel enzymatic biosensor based on glutathione peroxidase (GSH-Px), graphene oxide (GO) and nafion for the electrochemical sensing of glutathione (GSH) in body fluids. GSH-Px was immobilized covalently via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) onto modified glassy carbon electrode (GCE) decorated with GO and nafion and successfully used for sensing of GSH in the presence of H₂O₂ as catalyst with Michaelis-Menten constant about 0.131 mmol/L. The active surface are of GCE improve from 0.183 cm² to 0.225 cm² after modification with GO. The introduced biosensor (GSH-Px/GO/nafion/GCE) was used for monitoring of GSH over the range 0.003-370.0 μM, with a detection limit of 1.5 nM using differential pulse voltammetric (DPV) method. The GSH-Px/GO/nafion/GCE was successfully applied to the determination of GSH in real samples.

Three-dimensional porous reduced graphene oxide decorated with carbon quantum dots and platinum nanoparticles for highly selective determination of azo dye compound tartrazine

In this work, an electrochemical sensor for the azo dye compound tartrazine (TRT) determination was proposed. A screen-printed carbon electrode (SPCE) was modified by depositing three-dimensional porous reduced graphene oxide decorated with carbon quantum dots and platinum nanoparticles (Pt/CQDs@rGO/SPCE). The resulting amount of TRT was observed by differential pulse voltammetry. Under optimal conditions, the sensor exhibited two wide linearities ranging from 0.01 to 1.57 μM and 1.57-9.3 μM with the reliability coefficient of determination of 0.991 and 0.992, respectively. The detection limit (LOD) was also estimated to be 7.93 nM. Moreover, the Pt/CQDs@rGO/SPCE suggested high selectivity in the presence of several interfering agents and azo dye compounds that have a similar structure. Additionally, the Pt/CQDs@rGO/SPCE revealed superior recovery values of about 96.5-101.6% for candy, 99.7-103.5% for soft drinks, 96.0-101.2% for jelly powder, and 98.0-103.0% for water samples. Furthermore, the fabricated sensor exhibits excellent selectivity, stability, reproducibility, and repeatability, indicating a great perspective in the monitoring of TRT. Therefore, it can be speculated that the proposed electrode could be effectively applied to determine TRT in food samples.

Voltammetric sensor based on bimetallic nanocomposite for determination of favipiravir as an antiviral drug

A novel and sensitive voltammetric nanosensor was developed for the first time for trace level monitoring of favipiravir based on gold/silver core–shell nanoparticles (Au@Ag CSNPs) with conductive polymer poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) and functionalized multi carbon nanotubes (F-MWCNTs) on a glassy carbon electrode (GCE). The formation of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT composite was confirmed by various analytical techniques, including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and field-emission scanning electron microscopy (SEM). Under the optimized conditions and at a typical working potential of + 1.23 V (vs. Ag/AgCl), the Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE revealed linear quantitative ranges from 0.005 to 0.009 and 0.009 to 1.95 µM with a limit of detection 0.46 nM (S/N = 3) with acceptable relative standard deviations (1.1-4.9 %) for pharmaceutical formulations, urine, and human plasma samples without applying any sample pretreatment (1.12–4.93%). The interference effect of antiviral drugs, biological compounds, and amino acids was negligible, and the sensing system demonstrated outstanding reproducibility, repeatability, stability, and reusability. The findings revealed that this assay strategy has promising applications in diagnosing FAV in clinical samples, which could be attributed to the large surface area on active sites and high conductivity of bimetallic nanocomposite.

Construction of a simple and selective electrochemical sensor based on Nafion/TiO2 for the voltammetric determination of olopatadine

A selective and facile voltammetric method based on titanium dioxide nanoparticles and Nafion (Nafion/TiO2 NPs) on the screen-printed electrode (SPE) was proposed for olopatadine determination. Followed by the synthesis of TiO2 nanoparticles, various methods, including high-resolution transmission electron microscopy (HR-TEM), ultraviolet-visible spectroscopy (UV-Vis), energy-dispersive X-ray (EDX) Raman spectrum, and electrochemical impedance spectroscopy (EIS) were utilized to characterize the nanomaterials. Nafion/TiO2 on the screen-printed electrode (NFN/TiO2/SPE) was used to determine olopatadine in concentration ranges of 0.01 to 0.07 and 0.07 to 14.6 µM with a limit of quantification as low as 7.0 nM, via differential pulse voltammetry technique. The NFN/TiO2/SPE offered a high-performance ability to determine olopatadine in the eye drop sample with satisfactory recovery data of 98.2–99.0 %. Also, the developed electrode showed good reproducibility, repeatability, and high selectivity features. The obtained results indicate that NFN/TiO2/SPE could be utilized as an appropriate candidate for electrochemical olopatadine sensing.

Sensitive and Selective Electrochemical Detection of Epirubicin as Anticancer Drug Based on Nickel Ferrite Decorated with Gold Nanoparticles

The accurate and precise monitoring of epirubicin (EPR), one of the most widely used anticancer drugs, is significant for human and environmental health. In this context, we developed a highly sensitive electrochemical electrode for EPR detection based on nickel ferrite decorated with gold nanoparticles (Au@NiFe₂O₄) on the screen-printed electrode (SPE). Various spectral characteristic methods such as Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), energy-dispersive X-ray spectroscopy (EDX) and electrochemical impedance spectroscopy (EIS) were used to investigate the surface morphology and structure of the synthesized Au@NiFe₂O₄ nanocomposite. The novel decorated electrode exhibited a high electrocatalytic activity toward the electrooxidation of EPR, and a nanomolar limit of detection (5.3 nM) was estimated using differential pulse voltammetry (DPV) with linear concentration ranges from 0.01 to 0.7 and 0.7 to 3.6 µM. The stability, selectivity, repeatability reproducibility and reusability, with a very low electrode response detection limit, make it very appropriate for determining trace amounts of EPR in pharmaceutical and clinical preparations.

Trade-off efficacy and data processing strategy in the power of spectral resolution of co-formulated antihypertensive pharmaceuticals

Versatile, extraction-free univariate spectrophotometric methods have been modified to get effective spectral resolution of mixtures in accordance with their feature challenges. The proposed methods have been applied and validated for analyzing some antihypertensive medicines in their co-formulated medicinal products. Two mixtures have been used: the first one [Mix I _(OLM/ADB)] is composed of Olmesartan medoxomil (OLM) and Amlodipine besylate (ADB) with partly-overlapped spectra while the second [Mix II _(TEL/HCT)] is made up Telmisartan (TEL) and Hydrochlorothiazide (HCT) with total-overlapped spectra. Induced dual wavelength, absorbance correction and ratio subtraction coupled with constant multiplication methods were applied to Mix I _(OLM/ADB), while dual wavelength, advanced absorbance subtraction and constant center coupled with spectrum subtraction methods were applied to Mix II _(TEL/HCT). Calibration graphs were established with good correlation coefficients. The methods exhibit significant advantages as simplicity, sensitivity, minimal data manipulation besides optimum robustness. Selectivity was inspected using lab-mixtures with diverse ratios. Accuracy, precision and repeatability were found to be within the acceptable limits. The proposed methods are good enough to be used for co-assay of analytes in combined forms without any interfering from excipients. Moreover, all results were estimated in accordance with ICH criteria and successfully compared with those of the reported methods applying t-test and F-test at 95% confidence level. Generally, these methods can be used efficiently for routine quality control testing.

A novel stability-indicating method for determination of a new antidepressant effect of vortioxetine in a pharmaceutical formulation by using RP-HPLC

Background

A novel rapid, accurate, and stability-indicating reversed-phase high performance liquid chromatographic (RP-HPLC) and first derivative spectrophotometric determination were explained for the assay of vortioxetine (VRT) in bulk and pharmaceutical formulations. For RP-HPLC method, optimal separation and determination of VRT were achieved with a Waters Symmetry C18, (100 × 4.6 mm, 3.5 μm) analytical column using a mobile phase consisting of methanol:0.05 M potassium dihydrogen phosphate (pH:3.0 ± 0.05) (30:70, v/v) in isocratic mode with flow rate of 1.3 mL min−1. Injection volume was 20 μL. The maximum absorption wavelength of VRT is 225.0 nm; hence, 225.0 nm was studied as the detection wavelength and column at 50 °C temperature. The caffeine was used as the internal standard (IS). On the other hand, the first derivative spectrophotometric method for the analysis of vortioxetine was performed by measuring the amplitude at 251.7 and 272.6 nm.

Result

The HPLC method was found to be linear in the concentration ranges of 10.0-70.0 μg mL−1 with the coefficient value R2 of 0.9998, and the mean recovery value was 100.7%. Further stability studies were done through exposure of the analyte solutions to various stress conditions: acid, alkali hydrolysis, chemical oxidation, and exposure to UV radiation. For the first derivative spectrophotometric method, linearity was observed in the concentration range 6.0-30.0 μg mL−1 (for 237.7 nm R2 = 0.9999 and for 257.2 nm R2 = 0.9997).

Conclusion

The methods were validated in accordance with ICH guidelines with respect to linearity, accuracy, specificity, limit of detection, precision, and limit of quantification.