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A ternary mixture incorporating Hydroxyzine hydrochloride (HYX), Ephedrine hydrochloride (EPH) and Theophylline (THP) frequently prescribed for the treatment of respiratory diseases. Herein, two spectrophotometric methods are designated and applied to resolve these three components in their mixture. Method A is ratio-subtraction combined with derivative spectrophotometry, where THP can be determined directly at its λmax 271 nm (neither HYX or EPH interfere), then for determination of HYX and EPH, the ternary mixture was divided by 22 μg/mL of THP and after subtraction of the plateau region, HYX can be determined directly at its λmax 234.2 nm (absence of EPH intervention). Finally, the third derivative (3D) spectrophotometric approach was utilized to estimate EPH by detecting the peak amplitude at 222 nm with Δλ = 4 and a scaling factor 100. Principal Component Regression (PCR) and Partial Least Squares (PLS), two multivariate calibration approaches, were applied effectively in Method B. This method effectively quantified the mixture under investigation by using the absorption spectra obtained from suitable solutions of the three components in the 210-230 nm region. The calibration models were evaluated using cross-validation with PCR and PLS, producing statistical characteristics that demonstrate the effectiveness of the calibration models. Synthetic and pharmaceutical preparations were also used to conduct external validation. In pharmaceutical formulation, these methods were successfully applied to analyze HYX, EPH, and THP without overlap from formulation's excipients. Moreover, the study's findings were statistically contrasted with those of earlier reported HPLC method. Appraisal approaches were used to determine whether the new spectrophotometric methods had an adverse environmental impact involving the Green Analytical Procedure Index (GAPI) and the AGREE (Analytical Greenness). These evaluations delivered information about the methods' eco-friendliness and sustainability, proving that they are in line with ecologically attributed practices. Furthermore, the Blue Applicability Grade Index (BAGI) was utilized to identify and verify the feasibility and practicality of the suggested approaches., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright: © 2024 AlSalem et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are two commonly used antioxidants with potential health risks associated with excessive intake from multiple sources. Several countries have implemented strict regulations to curb these risks. This study presents a simple LC-MS/MS method for estimating BHT and BHA levels in Salmo salar, butter, and milk. To mitigate any potential interference from the three complex matrices with the ionisation of the target analytes, the method utilised the standard addition approach. The mobile phase used to elute the analytes consisted of 0.1 % formic acid in a mixture of water and acetonitrile (25:75 v/v). Both antioxidants were detected in negative ionisation mode. BHT was identified through single-ion monitoring at a mass-to-charge ratio (m/z) of 219.4, while BHA was detected using multiple-reaction monitoring, with a transition from m/z 164.0 to 149.0. The environmental assessment of the applied procedures verified that the approach is eco-friendly., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A selective, precise, and accurate reversed HPLC method has been developed and validated for simultaneous separation and determination of two veterinary drugs, dipyrone and hyoscine, in their combined dosage form in the presence of their official impurities, namely 4-aminoantipyrine and tropic acid, in addition to the formulated preservative: phenol. The linearity range was found to be (1.00-35.00 µg/mL) for dipyrone and (2.50-50.00 µg/mL) for hyoscine. It exhibited a satisfactory linearity regression R (0.9999) for both drugs with LOD 0.22 µg/mL and 0.72 µg/mL and LOQ 0.65 µg/mL and 2.19 µg/mL for dipyrone and hyoscine, respectively. Additionally, the two cited drugs were also determined in the presence of dipyrone active metabolite 4-aminoantipyrine using diclofenac as an internal standard in bovine urine. The linearity range was found to be (15-75 µg/mL) for dipyrone, (2.5-60 µg/mL) for hyoscine, and (2.5-60 µg/mL) for 4-aminoantipyrine with linearity regression R (0.9999-0.9998). The LLOQ (15, 2.5, 2.5 µg/mL), LQC (45, 7.5, 7.5 µg/mL), MQC (55, 25, 25 µg/mL), and HQC (60, 50 50 µg/mL) were determined for dipyrone, hyoscine and 4-aminoantipyrine, respectively. UV detection was carried out at 220 nm. The method was validated according to the ICH guidelines, as well as according to FDA guidelines for determining both drugs in bioanalytical matrices and both proved accuracy and precision. A statistical comparison was made between the results obtained and those obtained by the reported method, showing no significant difference in accuracy and precision at p = 0.05. The suggested method was proved eco-friendly through a greenness assessment using two different tools (The analytical eco-scale scored 83, and the AGREE-Analytical Greenness Metric approach scored 0.83). The suggested method can be used in the routine work of quality control labs, screening for drug abuse, and ensuring clean sport for horse racing., (© 2024. The Author(s).)

Tulathromycin (TUL) is a widely used veterinary antibiotic for treating bovine and porcine respiratory infections. Consuming animal-derived food contaminated with this medication may jeopardize human health. This work adopted the first portable potentiometric platform for direct TUL sensing in pharmaceutical and food products. The sensor employed a plasticized PVC membrane on a glassy carbon electrode doped with calix[6]arene and multi-walled carbon nanotubes (MWCNT) in a single solid contact layer for selective binding and signal stability. Characterization via scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the material's integrity. The MWCNT-based sensor produced a stable Nernstian response (1.0 × 10 -7 to 1.0 × 10 -3 M) and a limit of detection (LOD) of 9.76 × 10 -8 M with instantaneous response (8 ± 2 s). IUPAC validation revealed high selectivity for TUL against interfering ions, minimal drift (0.6 mV/h), and functionality over a broad pH range (2.0-7.0), allowing direct application to dosage form, spiked milk, and liver samples. Eco-Scale, AGREE, and Whiteness assessment proved the method's ecological sustainability, economic viability, and practical feasibility, surpassing traditional approaches., (© 2024. The Author(s).)

A cost-effective, selective, sensitive, and operational TLC-densitometric approach has been adapted for the concurrent assay of Hydroxyzine Hydrochloride (HYX), Ephedrine Hydrochloride (EPH), and Theophylline (THP) in their pure powder and pharmaceutical forms. In the innovative TLC-densitometric approach, HYX, EPH, and THP were efficaciously separated and quantified on a 60F 254 silica gel stationary phase with chloroform-ammonium acetate buffer (9.5:0.5, v / v ) adjusted to pH 6.5 using ammonia solution as a mobile liquid system and UV detection at 220 nm. The novel TLC method validation has been performed in line with the international conference for harmonization (ICH) standards and has been effectively used for the estimation of the researched medicines in their pharmaceutical formulations without intervention from excipients. Additionally, parameters affecting the chromatographic analysis have been investigated. The new TLC approach's functionality and greenness were appraised using three modern and automated tools, namely the Blue Applicability Grade Index (BAGI), the Analytical Greenness metric (AGREE), and the Green Analytical Procedure Index (GAPI) tools. In short, the greenness characteristics were not achieved as a result of using mandatory, non-ecofriendly solvents such as ammonia and chloroform. On the contrary, the applicability and usefulness of the novel TLC approach were attained via concurrent estimation for the three drugs using simple and straightforward procedures. Moreover, the novel TLC method outperforms previously published HPLC ones in terms of the short run time per sample and moderate pH value for the liquid system. According to the conclusions of comparisons with previously recorded TLC methods, our novel HPTLC method has the highest AGREE score, so it is the greenest HPTLC strategy. Moreover, its functionality and applicability are very appropriate because of the simultaneous assessment of three drugs in one TLC run. Furthermore, no tedious and complicated extraction and evaporation processes are prerequisites.

Nowadays, scientists are currently attempting to lessen the harmful effects of chemicals on the environment. Stability testing identifies how a drug's quality changes over time. The current work suggests a first and sustainable differential pulse voltammetry technique for quantifying difluprednate (DIF) as an anti-inflammatory agent in the presence of its alkaline degradation product (DEG). The optimum conditions for the developed method were investigated with a glassy carbon electrode and a scan rate of 100 mV s -1 . The linearity range was 2.0 × 10 -7 -1.0 × 10 -6  M for DIF. DIF was found to undergo alkaline degradation, when refluxed for 8 h using 2.0 M NaOH, and DEG was successfully characterized utilizing IR and MS/MS. The intended approach demonstrated the selectivity for DIF identification in pure, pharmaceutical, and degradation forms. The student's t-test and F value were used to compare the suggested and reported approaches statistically. The results were validated according to ICH requirements. The greenness of the studied approach was evaluated using the Green Analytical Procedure Index and the Analytical Greenness metric. Additionally, the whiteness features of the proposed approach were examined with the recently released red, green, and blue 12 model, and the recommended strategy performed better than the reported approaches in greenness and whiteness., (© 2024. The Author(s).)

Two rapid, precise, and sensitive stability-indicating high performance chromatographic methods for the measurement of Teriflunomide in its degradation products' existence were developed. These were RP-HPLC and HPTLC using UV detector. HPLC separation was accomplished utilizing Thermo BDS hypercil C18 column (250 × 4.6 mm, 5 μm) and acetonitrile: 0.03 M potassium dihydrogen phosphate: triethylamine (50:50:0.1%, by volume) as mobile phase at flow rate of 1mL/min. The separated peaks were detected at 250.0 nm. The densitometric approach was conducted utilizing HPTLC 60 F254 silica gel plates, and a developing system of benzene: ethanol: acetic acid (7.5:1:0.25, by volume) and detection was done at 250.0 nm. The developed approaches were evaluated regarding the International Conference on Harmonization (ICH) instructions. The calibration curves of both techniques were constructed with linearity ranges of (5-100) µg/mL and (2-10) µg /band, for HPLC and densitometric determination, consecutively. Teriflunomide was exposed to base and acid hydrolysis, oxidation using H 2 O 2 and finally, thermal degradation as stated in ICH guidelines. The degradation product structures' elucidation was achieved through LC-MS., (© 2024. The Author(s).)

Two rapid, smart and validated stability indicating HPLC and TLC techniques were developed to determine atenolol (ATE) and lercanidipine HCl (LER) simultaneously in their pharmaceutical formulation. HPLC chromatographic separation was implemented by using Microsorb C18 (250 × 4.6 mm, 5 μm) column, with mobile phase of acetonitrile and 20 mM potassium dihydrogen phosphate buffer pH 3.5 adjusted by orthophosphoric acid in the ratio of (65:35, v/v) at a flow rate of 1.2 mL/min at 240 nm also the injection volume adjusted to be 30 μL. These selected conditions effectively separated ATE and LER at a retention time of 2 and 6.7 min, respectively, by isocratic elution mode without any interference from the obtained degradation products of LER. The densitometric determination was performed by using precoated silica gel 60F254 aluminum plates and chloroform, methanol and triethylamine (11.3:1.3: 0.3, by volume) as a developing system. The detection wavelength for simultaneous estimation of both drugs was 240 nm in the presence of the oxidative product of LER. The RF values for ATE and LER were 0.22 and 0.78, respectively. The calibration curves of both techniques were constructed with linearity ranges of (5-55) μg.mL-1 and (1-55) μg.mL-1 for both ATE and LER, respectively, for HPLC determination. While for TLC, the linearity ranges were (1-4) μg/band and (0.2-1.4) μg/band for ATE and LER, respectively. LER degradation products were characterized using UPLC/MS and the suggested mechanisms and degradation pathways were introduced., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are two antioxidants that have been extensively used in many applications. Both are well known for their debatable health risks due to their multiple intake sources. Therefore, conservative limits are set for them in different regulations adapted to the matrices in which they exist. Here we present a simple spectrofluorimetric method for the determination of BHT and BHA based on their native fluorescence and synchronous scanning mode. The type of solvent and the interval between emission and excitation wavelengths were carefully optimized. Under the optimized conditions, good linearities were obtained between the emission intensity and the corresponding concentrations of BHT and BHA over the range of 3-18 µg/mL and 0.1-7 µg/mL, respectively with a good correlation coefficient (r > 0.99). The limits of detection were 0.9 and 0.02 µg/mL, and the quantification limits were 3 and 0.05 µg/mL for BHT and BHA, respectively. The suggested procedure was validated according to ICH guidelines Q2 (R1). Furthermore, the method's greenness was assessed by three different methods, and it proved to be eco-reasonable. The method was successfully applied to the determination of BHT and BHA in pharmaceutical formulations. We also applied the suggested method for monitoring the residual BHA in conventional, powdered milk and butter, with good recovery in spiked samples., (© 2024. The Author(s).)

High performance liquid chromatography is one of the techniques of choice for the separation and quantitative determination of drugs in mixture form. Ipriflavone, ascorbic acid, pyridoxine, vitamin D3, and lysine are formulated together as an adjuvant combination in osteoporosis. In this work, we developed and validated two complementary high performance liquid chromatographic methods to determine the five compounds in their pharmaceutical dosage form. The first method (method A) was capable of determining ipriflavone, ascorbic acid, pyridoxine, and vitamin D3 in their bulk and combined pharmaceutical formulation. The method is based on Liquid Chromatographic separation with UV detection at 254 nm using Agilent Eclipse XDB-C18 column with a mobile phase consisting of 25 mM ammonium acetate buffer (pH 4.2): methanol in gradient mode. Due to the high polarity of lysine, it was difficult to achieve satisfactory retention on reversed phase columns. So, we separated it on a strong cation exchange column (Exsil 100 SCX) without derivatization with a mobile phase consisting of 10 mM sodium dihydrogen phosphate and 200 mM sodium chloride (pH 6) with UV detection at 210 nm (method B). Validation of the proposed methods was performed according to ICH guidelines Q2(R1). The proposed methods proved to be valid for selective analysis of the stated drugs in their bulk and combined pharmaceutical formulation. Greenness assessment of the developed methods was evaluated using three assessment tools: ESA, GAPI and the most recently developed tool AGREE, showing a satisfactory comprehensive guide of the greenness of the developed methods., (© 2024. The Author(s).)

Preserving the environment, reducing the amount of waste resulting from chemical trials, and reducing the amount of energy consumed have currently become a pivotal global trend. An analytical quality by design (AQbD) based eco-friendly TLC-densitometric method was implemented for quantifying two antihypertensive agents, captopril (CPL) and hydrochlorothiazide (HCZ), along with their impurities; captopril disulphide (CDS), chlorothiazide (CTZ) and salamide (SMD). The analytical target profile (ATP) was first identified, followed by selecting the critical analytical attributes (CAAs), such as retardation factors and resolution between the separated peaks. Critical method parameters (CMPs) that may have a crucial influence on CAAs were identified and emanated through the quality risk assessment phase. A literature survey-based preliminary studies were performed, followed by optimization of the selected CMPs through a custom experimental design to attain the highest resolution with optimum retardation factors. Moreover, method robustness was also tested by testing the design space. Complete separation of the drugs and their impurities was achieved using ethyl acetate: glacial acetic acid (6: 0.6, v/v) as a developing system applied to a 12 cm length TLC plate at room temperature with UV scanning at 215 nm. Calibration graphs were found to be linear in the ranges of (0.70-6.00), (0.10-2.00), (0.20-1.00), (0.07-1.50) and (0.05-1.00) µg/band corresponding to CPL, HCZ, CDS, CTZ, and SMD, respectively. Four different green metric tools were used to evaluate the greenness profile of the proposed method, and results showed that it is greener than the reported HPLC method. Method whiteness assessment was also conducted. Moreover, the method performance was evaluated following the ICH guidelines, and the outcomes fell within the acceptable limits. The developed method could be approved for routine assay of the cited components in their pharmaceutical formulations and bulk powder without interference from the reported impurities. The issue of concern is saving money, especially in developing countries., (© 2024. The Author(s).)

Benzodiazepines (BZDs) are a group of drugs prescribed for their sedating effect. Their misuse and addictive properties stipulate different authorities for developing simple, fast and accurate analytical methods for instantaneous detection. Differential pulse voltammetric technique (DPV) was utilized for the selective assay of midazolam hydrochloride (MDZ) in the pure, parenteral dosage forms and plasma samples. A chemically modified carbon paste electrode (CPE) was implemented during the study. The method depended on the electroreduction of MDZ on the surface of the electrode over a potential range of 0.0 V to -1.6 V. The electrode was fabricated using silica nanoparticles (Si-NPs) which were incorporated into the composition of the CPE and used to enhance the electrode performance. Then, to enhance the sensitivity of the method, a chronoamperometric modification step was applied for depositing gold nanoparticles (Au-NPs) on the carbon paste electrode surface. Modification with Au-NPs showed a higher reduction current peak for MDZ with well-defined peaks. Various parameters such as pH of the media and measurements scan rate were investigated and optimized to enhance the sensor sensitivity. The sensor showed a dynamic linear response over a concentration range of 4.0 × 10 -7  M to 2.9 × 10 -4  M of MDZ with a LOD of 2.24 × 10 -8  M using 0.1 M acetate buffer (pH 5.6). The sensor was validated in accordance with the ICH guidelines regarding accuracy, precision and specificity for the selective assay of MDZ in the presence of excipients. A greenness evaluation was performed using three different assessment tools, namely, the "Green Analytical Procedure Index" (GAPI), the "Analytical Greenness metric" (AGREE) and the "Whiteness Analytical Chemistry tool" (WAC) using the RGB12 model., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The use of sustainable solvents has increased significantly in recent years due to advancements in green analytical methods. The number of impurities in the drug substance determines how safe the finished product is. Therefore, during the whole medication planning process, contaminants need to be closely watched. Using chemometric models, the concentrations of hyoscine N-butyl bromide (HYO) and paracetamol (PAR) were determined in the presence of three PAR impurities [P-nitrophenol (PNP), P-aminophenol (PAP), and P-chloroacetanilide (PCA), as well as DL-tropic acid (TRO) as a HYO impurity]. It was possible to isolate and measure these dangerous impurities. Fever and spasms associated with COVID-19 are reported to be considerably reduced when PAR and HYO are taken together. Artificial neural networks, principal component regression, multivariate curve resolution-alternating least squares, and partial least squares are the four chemometric-assisted spectrophotometric models that were created and verified. All of the proposed methods' quantitative analytical potency was assessed using recoveries%, root mean square error of prediction, and standard error of prediction. For PAR, HYO, PNP, PCA, TRO, and PAP, respectively, the indicated approaches were used in the ranges of 4.00-8.00, 16.00-24.00, 1.00-5.00, 0.40-0.80, 4.00-12.00, and 2.00-6.00 µg/mL. They are able to get around difficulties like collinearity and spectral overlaps. After statistical testing, there was no discernible difference between the recommended methods and the published one. The degree of greenness of the established models was evaluated using three different green assessment methods. In the presence of their harmful impurities, PAR and HYO could be identified using the recommended methods., (© 2023. The Author(s).)

The multivariate models that are used for spectral data analysis have many beneficial applications, and one of the important applications is the analysis of drugs and their impurities. Three Chemometrically-assisted spectrophotometric models have been proposed and validated. The proposed models are Partial Least Squares (PLS), Artificial Neural Networks (ANN), and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). The advanced chemometric models were applied to resolve the significantly overlapping spectra of Etoricoxib (ETO) and Paracetamol (PCM), along with impurities of PCM namely; P-aminophenol (PAP) and P-hydroxy acetophenone (PHA). The proposed models succeeded in simultaneously analyzing the mixture of ETO and PCM along with the impurities of PCM. So, the proposed techniques can be used without requiring a separation step in the analysis of pharmaceutical formulation. Moreover, no significant differences were found when the results of the suggested and published chemometric models were compared statistically with the reported HPLC method., (© 2023. The Author(s).)

Two accurate, sensitive, and selective methods for simultaneous determination of miconazole nitrate (MIC), nystatin (NYS), and metronidazole (MET) in pure state or drug product were established and verified. First, RP-HPLC-DAD was designed. Separation was accomplished using a ZOBRAX Eclipse Plus RP-C 8 column that was running under an isocratic elution of methanol: 0.05% aqueous solution of sodium dodecyl sulphate (40: 60 v/v), with a flow rate that was regulated at 0.8 mL/min. The column temperature was adjusted at 25 °C and diode array detector was monitored at 220 nm. The linearity range of the proposed method was achieved at the concentration of 5-50, 4-50, and 4-40 µg/mL and the attained retention time for the studied drugs was 2.52, 3.52 and 4.99 min for MIC, NYS, and MET, correspondingly. Second, a TLC-densitometric approach was used to resolve the three compounds. Resolution of the three cited drugs was carried out using TLC aluminum plates pre-coated with 0.25 mm silica gel 60 F 254 . A developing solvent comprised ethyl acetate: toluene: methanol: triethyl amine: formic acid (3: 1: 7: 0.3: 0.1 by volume) (pH = 5.5) was utilized and scanning of the resolved bands at 215 nm. Linearity of the developed TLC method was evaluated and evident to be 0.4-2, 0.4-2.2, and 0.4-2 μg/band for MIC, NYS, and MET, in that order. The suggested chromatographic methods were verified according to ICH directives. The findings of the developed chromatographic procedures were statistically compared with the results of the reported ones using student's t-test and F-test. Furthermore, two green assessment tools evaluated the indicated methods' level of greenness (GAPI and AGREE)., (© 2023. The Author(s).)

Hypertension is described by the world health organization (WHO) as a serious medical problem that significantly affects the heart, brain and kidneys. It is a major cause of premature death worldwide. The present study aims to quantify the combination of captopril (CPL), hydrochlorothiazide (HCZ) and their harmful impurities; captopril disulphide (CDS), chlorothiaizde (CTZ) and salamide (SMD). In-silico study was conducted for estimation of pharmacokinetic parameters (ADMET) as well as toxicity profile of the proposed impurities. The results showed that the three impurities under investigation had poor permeability to CNS and cannot pass the blood-brain barrier (BBB), reducing the likelihood of causing side effects in the brain. On the other hand, all studied impurities were found to be hepatotoxic. In consequence, a highly sensitive and green ultra-performance liquid chromatography- tandem mass spectrometric (UPLC/MS/MS) method was developed and validated for separation of the cited drugs in the presence of their harmful impurities; methanol and 0.1% formic acid (90:10, v/v) mixture was used as a mobile phase, eluted at a constant flow rate of 0.7 mL/min at room temperature. Detection was adopted using a tandem mass spectrometer in a positive mode only for CPL and negative mode for HCZ, CDS, CTZ and SMD. Separation was performed within 1 min. Calibration graphs were found to be linear in the ranges of (50.0-500.0 ng mL -1 ), (20.0-500.0 ng mL -1 ), (10.0-250.0 ng mL -1 ), (5.0-250.0 ng mL -1 ) and (20.0-400.0 ng mL -1 ) corresponding to CPL, HCZ, CDS, CTZ and SMD, respectively. Additionally, comparative study of greenness profile was established for the proposed and reported methods using five green metric tools. The proposed method was found to be greener than the reported HPLC method. The developed (UPLC/MS/MS) method was validated according to (ICH) guidelines and it was found to has greater sensitivity, shorter analysis time and lower environmental impact compared to the reported methods., (© 2023. The Author(s).)

Three smart carbon paste electrodes were fabricated to quantify dorzolamide hydrochloride DRZ, including conventional carbon paste I, modified carbon paste embedding Silica II, and modified carbon paste embedding β-cyclodextrin III. This study is based on the insertion of DRZ with phosphomolybdic acid to create an electroactive moiety dorzolamide-phosphomolybdate ion exchanger using a solvent mediator dibutyl phthalate. The three constructed carbon paste electrodes displayed Nernstian responses and linear concentration ranges with lower detection limits. The vital performance of the created electrodes was verified in relation to various parameters. The electrodes enhance the selective determination of DRZ in the presence of inorganic ions, a co-formulated drug in the dosage form timolol maleate, and the excipient benzalkonium chloride. The modified carbon paste electrode including Silica was utilized to detect DRZ in ophthalmic eye drop form utilizing the direct calibration curve and potentiometric titration methods. Satisfactory findings were achieved by comparing them to other reported methods., (© 2023. Springer Nature Switzerland AG.)

An economical & eco-friendly spectrofluorometric method has been developed for the determination of prucalopride succinate (PRU) in human urine on the basis of the drug's native fluorescence. The type of solvent and the wavelengths of excitation and emission have been carefully selected for optimal experimental conditions. In deionized water, the fluorescence intensity was measured at λ emission 362 nm upon excitation at 310 nm. This bio-validated method was carried out using 30uL urine without any preliminary steps. The calibration curve for prucalopride succinate shows a linear relationship in a concentration range of 0.75-5.5 µg/mL. Accuracy and precision were obtained using 4 quality control samples which are: 0.75 μg/ mL (LLOQ), 2.25 μg/mL (QCL), 2.5 μg/mL (QCM) & 4.125 µg/mL (QCH). The validation of this proposed technique obeys European Medicines Agency (EMA) Guidelines for validating bioanalytical methods and the greenness assessment was evaluated according to the Analytical GAPI approach., (© 2023. The Author(s).)

Triamterene (TRI) and xipamide (XIP) mixture is used as a binary medication of antihypertension which is considered as a major cause of premature death worldwide. The purpose of this research is the quantitative and qualitative analysis of this binary mixture by green univariate and multivariate spectrophotometric methods. Univariate methods were zero order absorption spectra method (D 0 ) and Fourier self-deconvolution (FSD), as TRI was directly determined by D 0 at 367.0 nm in the range (2.00-10.00 µg/mL), where XIP show no interference. While XIP was determined by FSD at 261.0 nm in the range (2.00-8.00 µg/mL), where TRI show zero crossing. Multivariate methods were Partial Least Squares, Principal Component Regression, Artificial Neural Networks, and Multivariate Curve Resolution-Alternating Least Squares. A training set of 25 mixtures with different quantities of the tested components was used to construct and evaluate them, 3 latent variables were displayed using an experimental design. A set of 18 synthetic mixtures with concentrations ranging from (3.00-7.00 µg/mL) for TRI and (2.00-6.00 µg/mL) for XIP, were used to construct the calibration models. A collection of seven synthetic mixtures with various quantities was applied to build the validation models. All the proposed approaches quantitative analyses were evaluated using recoveries as a percentage, root mean square error of prediction, and standard error of prediction. Strong multivariate statistical tools were presented by these models, and they were used to analyze the combined dosage form available on the Egyptian market. The proposed techniques were evaluated in accordance with ICH recommendations, where they are capable of overcoming challenges including spectral overlaps and collinearity. When the suggested approaches and the published one were statistically compared, there was no discernible difference between them. The green analytical method index and eco-scale tools were applied for assessment of the established models greenness. The suggested techniques can be used in product testing laboratories for standard pharmaceutical analysis of the substances being studied., (© 2023. The Author(s).)

Pholcodine and guaiacol are widely used together in pharmaceutical syrups for cough treatment. On the other hand, the Ultra Performance Liquid Chromatographic technique is characterized by having the power of increasing chromatographic efficiency and decreasing run time compared to the traditional High Performance Liquid Chromatographic one. In this work, this power was exploited for the simultaneous determination of pholcodine, guaiacol along with three guaiacol impurities, namely; guaiacol impurity A, guaiacol impurity B, and guaiacol impurity E. Good separation was achieved by employing Agilent Zorbax C8 column (50 × 2.1 mm) as the stationary phase, and acetonitrile: phosphate buffer pH 3.5 (40: 60, by volume) as a mobile phase. The proposed method was validated as per International Council for Harmonisation guidelines. Linear relationships, at ranges of 50-1000 µg mL -1 for pholcodine and 5-100 µg mL -1 for guaiacol and the three related impurities, were established. Finally, the proposed method was applied for pholcodine and guaiacol determination in Coughpent® syrup and compared favorably to the reported one., (© 2023. The Author(s).)

Two thin layer chromatography (TLC) methods have been developed for the determination of pesticides residues of imidacloprid (IMD) and deltamethrin (DLM) in thyme and guava leaves. In the two methods, the used stationary phase was silica gel 60 F 254 plates impregnated in chitosan nanoparticles (ChTNPs) 0.5% to improve separation using a green developing system consists of isopropyl alcohol for IMD and n-hexane-toluene-ethylacetate for DLM. The two pesticides were determined quantitatively, after TLC separation, at wavelengths 270.0 nm for IMD and 230.0 nm for DLM. Validation of both approaches was carried out in agreement with the guidelines of International Conference on Harmonization (ICH) and found to be selective, reliable and reproducible. Limits of detection of IMD and DLM were 0.002 and 0.00116 μg/spot, respectively. The newly developed TLC methods were used to monitor the pre-harvest interval estimation. Analytical eco-scaling depending on penalty points for IMD was calculated and showed that this method was eco-friendlier than the reported one., (© 2023. The Author(s).)

Misuse of illicit drugs is a serious problem that became the primary concern for many authorities worldwide. Point-of-care (POC) diagnostic tools can provide accurate and fast screening information that helps to detect illicit drugs in a short time. A portable, disposable and reproducible core-shell molecularly imprinted polymer (MIP) screen-printed sensor was synthesized as a POC analyzer for the assay of the date rape drug "ketamine hydrochloride" in different matrices. Firstly, the screen-printed electrode substrate was modified electrochemically with polyaniline (PANI) as an ion-to-electron transducer interlayer to improve the potential signal stability. Secondly, core-shell MIP was prepared, the core consisting of silica nanoparticles prepared by Stober's method, while the MIP shell was synthesized onto silica nanoparticles surface by copolymerizing methacrylic acid functional monomer and the crossing agent; ethylene glycol dimethacrylate in the presence of ketamine as a template molecule. Finally, the core-shell MIP was incorporated into the PVC membrane as an ionophore and drop-casted over PANI modified screen-printed carbon electrode. The imprinting process and the morphology of MIP were examined using scanning electron microscopy, Fourier-transform infrared and X-ray photoelectron spectroscopic methods. The sensor exhibited a short response time within 3-5 s in a pH range (2.0-5.0). The potential profile indicated a linear relationship in a dynamic concentration range of 1.0 × 10 -6  M to 1.0 × 10 -2  M with a slope of 54.7 mV/decade. The sensor was employed to determine ketamine in biological matrices and beverages., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: The combination of pyridoxine hydrochloride (PYR) and doxylamine succinate (DOX) as an antiemetic binary mixture is used to treat nausea and vomiting during pregnancy., Objective: Two validated, accurate, and selective chemometric models were developed to assay binary mixture in the presence of DOX oxidative degradation product (DOX DEG) that could be characterized using LC-MS., Methods: Partial least squares (PLS) regression and principal component regression (PCR) were selected for the determination of our binary mixture in presence of degradation. To exhibit a training set of 25 mixtures that had various percentages of tested substances in five level 3 variables, an experimental design was chosen. A set of 18 synthetic mixtures in the concentration range 10.0-50.0 μg/mL, 12.00-20.0 μg/mL, and 6.0-30.0 μg/mL for PYR, DOX, and DOX DEG, respectively, were used in the construction of the calibration models. Then set of seven synthetic mixtures with different concentrations were used in the construction of the validation models., Results: In validation samples with low root mean square error of prediction (RMSEP), the suggested models successfully predicted the concentrations of our drugs. The models developed were evaluated by RMSEP calculation, and the values obtained were 0.341, 0.196, and 0.388 for PYR, DOX, and DOX DEG, respectively, using PLS. While using PCR, RMSEP calculation and the values obtained were 0.400, 0.256, and 0.375 for PYR, DOX, and DOX DEG, respectively. The developed models were validated according to ICH strategies., Conclusions: The corresponding methods are suitable to determine PYR and DOX in pure form, pharmaceutical dosage form, and in the presence of DOX DEG product., Highlights: The study of drug breakdown pathways is very important nowadays, so even in the presence of degradation and extreme spectral overlapping, the suggested PLS and PCR spectrophotometric approaches were able to identify PYR and DOX., (© The Author(s) 2022. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Etoricoxib (ETO), Paracetamol (PCM), and two toxic impurities for Paracetamol impurity K (4-aminophenol (PAP)) and impurity E (para-hydroxy acetophenone (PHA)) were separated using a simple and selective HPLC method that was tested for the first time. PCM is a commonly used analgesic and antipyretic medication that has recently been incorporated into COVID-19 supportive treatment. Pharmaceuticals containing PCM in combination with other analgesic-antipyretic drugs like ETO help to improve patient compliance. The studied drugs and impurities were separated on a GL Sciences Inertsil ODS-3 (250 × 4.6) mm, 5.0 µm column, and linear gradient elution was performed using 50 mM potassium dihydrogen phosphate adjusted to pH 4.0 with ortho-phosphoric acid and acetonitrile as mobile phase at 2.0 mL/min flow rate at 25 °C and UV detection at 220 nm. The linearity range was 1.5-30.0 µg/mL for ETO and PCM while 0.5-10.0 µg/mL for PAP and PHA, with correlation coefficients (r) for ETO, PCM, PAP, and PHA of 0.9999, 0.9993, 0.9996, and 0.9998, respectively. The proposed method could be used well for routine analysis in quality control laboratory., (© 2022. The Author(s).)

The experimental design extracts valuable information about the main effects and interactions from the least number of experiments. The current work constructs a solid-state sensor for selective assay of Ondansetron (OND) in pharmaceutical dosage form and plasma samples. During optimization, the Design Expert ® statistical package constructed a custom design of 15 sensors with different recipes. We fed the software with the experimentally observed performance parameters for each sensor (slope, LOQ, correlation coefficient, and selectivity coefficient for sodium ions). The computer software analyzed the results to construct a prediction model for each response. The desirability function was adjusted to optimize the Nernstian slope, minimize the LOQ and selectivity coefficients, and maximize the correlation coefficient (r). The practical responses of the optimized sensor were close to those predicted by the model (slope = 60.23 mV/decade slope, LOQ = 9.09 × 10 -6  M, r = 0.999, sodium selectivity coefficient = 1.09 × 10 -3 ). The sensor successfully recovered OND spiked to tablets and human plasma samples with mean percentage recoveries of 100.01 ± 1.082 and 98.26 ± 2.227, respectively. Results were statistically comparable to those obtained by the reference chromatographic method. The validated potentiometric method can be used for fast and direct therapeutic drug monitoring of OND co-administered with chemotherapeutic drugs in plasma samples., (© 2022. The Author(s).)

Cyclizine hydrochloride (CYC) and meclozine hydrochloride (MEC) are antihistaminic drugs generally co-formulated with pyridoxine hydrochloride (PYR) to treat nausea and vomiting in pregnancy. Several analytical techniques have been applied for the determination of CYC or MEC with PYR, but determination of CYC impurity; benzhydrol (BEH) or MEC impurity; or 4-chlorobenzophenone (BEP) has not been paid attention to. Therefore, micellar UPLC method is introduced for analysis of ternary mixtures containing PYR together with both CYC and BEH (mixture I) or MEC and BEP (mixture II). Chromatographic separation was achieved using a Hypersil gold C 8 column (50 × 2.1 mm, 1.9 μm) using 0.01 M sodium dodecyl sulfate modified to pH 3.5 using phosphoric acid:acetonitrile (45:55 by volume) for mixture I and 0.1% sodium dodecyl sulfate, 0.1% sodium bicarbonate adjusted to pH 2.6 by phosphoric acid:acetonitrile (47:53 by volume) for mixture II as mobile phases. The separated peaks were detected at 230 and 245 nm for mixtures I and II, respectively. The adopted methods were validated in conformance with the International Conference on Harmonization (ICH) recommendations and were properly applied in commercial pharmaceutical formulation analysis. Comprehensive ecological comparison was achieved, confirming a higher ecological value of the presented methods compared to the earlier reported methods., (© 2022 John Wiley & Sons, Ltd.)

Non-depolarizing neuromuscular blocking agent Rocuronium bromide was quantified in drug substance and drug product using reversed-phase liquid chromatographic method. Forced degradation studies were conducted for Rocuronium bromide in drug substance under acidic (2MHCl), basic (2MNaOH), oxidative (3% H2O2), thermal (135°C) and photolytic (254 nm) stress conditions. An Agilent H12 C18 column was used for separation using diammonium hydrogen phosphate buffer (pH 8; 0.04M)- acetonitrile (50:50; v/v) as mobile phase at flow rate of 1 mL/min. The quantification was done using UV detection at 210 nm. The limit of quantification and detection was 11.1 and 3.66 μg/mL, respectively, and the recovery percentage was 99% in drug substance and drug product. ICH guidelines were adopted for method validation. The proposed LC method monitored the degradation profile for Rocuronium bromide under various stress conditions and provided a specific LC method for its routine analysis. Besides, the MS data were used to identify all Rocuronium bromide degradation products and the possible degradation pathway was designated., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Turmeric is an indispensable culinary spice in different cultures and a principal component in traditional remedies. Toxic metanil yellow (MY), acid orange 7 (AO) and lead chromate (LCM) are deliberately added to adulterate turmeric powder. This work compares the ability of multivariate chemometric models with those of artificial intelligent networks to enhance the selectivity of spectral data for the rapid assay of these three adulterants in turmeric powder. Using a custom experimental design, we provide a data-driven optimization for the sensitive parameters of the partial least squares model (PLS), artificial neural network (ANN) and genetic algorithm (GA). The optimized models are validated using sets of genuine turmeric samples from five different geographical regions spiked with standard adulterant concentrations. The optimized GA-PLS and GA-ANN models reduce the root mean square error of prediction by 18.4%, 31.1% and 55.3% and 25.0%, 69.9% and 88.4% for MY, AO and LCM, respectively., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Background: Noising is an undesirable phenomenon accompanying the development of widely used chemometric models such as partial least square regression (PLSR) and support vector regression (SVR)., Objective: Optimizations of these chemometric models by applying orthogonal projection to latent structures (OPLS) as a preprocessing step which is characterized by canceling noise is the purpose of this research study. Additionally, a comprehensive comparative study between the developed methods was undertaken highlighting pros and cons., Methods: OPLS was conducted with PLSR and SVR for quantitative determination of pyridoxine HCl, cyclizine HCl, and meclizine HCl in the presence of their related impurities. The training set was formed from 25 mixtures as there were five mixtures for each compound at each concentration level. Additionally, to check the validity and predictive ability of the developed chemometric models, independent test set mixtures were prepared by repeating the preparation of four mixtures of the training set plus preparation of another four independent mixtures., Results: Upon application of the OPLS processing method, an upswing of the predictive abilities of PLSR and SVR was found. The root-mean-square error of prediction of the test set was the basic benchmark for comparison., Conclusion: The major finding from the conducted research is that processing with OPLS reinforces the ability of models to anticipate the future samples., Highlights: Novel optimizations of the widely used chemometric models; application of a comparative study between the suggested methods; application of OPLS preprocessing methods; quantitative determination of pyridoxine HCl, cyclizine HCl and meclizine HCl; checking the predictive power of developed chemometric models; analysis of active ingredients in their pharmaceutical dosage forms., (© AOAC INTERNATIONAL 2021. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Extraction is the leading critical stage in the analysis of nutraceuticals. Ginkgo biloba (GB) has gained interest because of its therapeutic usages., Objectives: The aim was to develop four cost-effective extraction techniques for the extraction of quercetin from GB in a sachet containing a mixture of nutraceuticals. These techniques are solid-phase extraction (SPE), liquid-liquid extraction, inverted dispersive liquid-liquid microextraction, and the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method., Method: Direct spectrophotometry was used to monitor the recovery of the standard quercetin throughout the optimization steps. The HPLC-UV method of analysis was optimized to quantify the yields from the extracts present in the complicated contents of the sachets. The present study was assessed by analytical Eco-Scale assessment (ESA) and the National Environmental Method Index (NEMI) for greenness in comparison with the literature., Results: SPE showed the best cleanup outcomes. ESA and NEMI showed an adequate greenness of the proposed extraction protocol., Conclusions: Quercetin (marker for GB) extraction from market nutraceutical sachets is considered an exemplar for analysis in the QC of nutraceuticals. Regarding the greenness results, the proposed method of extraction is better even with adequate greenness as the extraction was a one-step process, in comparison with multistep processes of previously published protocols. Accordingly, it is recommended for use in routine extraction and analysis of such nutraceuticals., Highlights: Four extraction protocols have been developed. For GB ternary-mixture sachets, proper recovery was obtained using C18 SPE. The assessment of greenness of the proposed protocol guaranteed the superiority of the presented method. Safer sorbents and chemicals are favored for use in routine extraction of nutraceuticals., (© AOAC INTERNATIONAL 2021. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The methacholine challenge test is considered to be the gold standard bronchoprovocation test used to diagnose asthma, and this test is always performed in pulmonary function labs or doctors' offices. Methacholine (MCH) acts by inducing airway tightening/bronchoconstriction, and more importantly, MCH is hydrolyzed by cholinesterase enzyme (ChE). Recently, the American Thoracic Society raised concerns about pulmonary function testing during the COVID-19 pandemic due to recently reported correlation between cholinesterase and COVID-19 pneumonia severity/mortality, and it was shown that cholinesterase levels are reduced in the acute phase of severe COVID-19 pneumonia. This work describes the microfabrication of potentiometric sensors using copper as the substrate and chemically polymerized graphene nanocomposites as the transducing layer for tracking the kinetics of MCH enzymatic degradation in real blood samples. The in-vitro estimation of the characteristic parameters of the MCH metabolism [Michaelis-Menten constant (K m ) and reaction velocity (V max )] were found to be 241.041 μM and 56.8 μM/min, respectively. The proposed sensor is designed to be used as a companion diagnostic device that can (i) answer questions about patient eligibility to perform methacholine challenge tests, (ii) individualize/personalize medical dosing of methacholine, (iii) provide portable and inexpensive devices allowing automated readouts without the need for operator intervention (iv) recommend therapeutic interventions including intensive care during early stages and reflecting the disease state of COVID-19 pneumonia. We hope that this methacholine electrochemical sensor will help in assaying ChE activity in a "timely" manner and predict the severity and prognosis of COVID-19 to improve treatment outcomes and decrease mortality., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Novel, accurate, selective, and rapid high-performance liquid chromatography mass spectrometry method was developed for simultaneous analysis of amoxicillin trihydrate, dicloxacillin sodium, and their official impurity 6-aminopenicillanic acid. The chromatographic separation was carried out by applying the mixture on a C 18 column (3.5  µ m ps, 100 mm × 4.6 mm id) using acetonitrile:water (65 : 35 by volume) as a mobile phase within only 4 min. The quantitative analysis was executed using single quadrupole mass spectrometer in which electrospray ionization, selected ion monitoring, and negative mode were operated. The retention times were 1.61, 2.54, and 3.50 mins for amoxicillin, 6-aminopenicillanic acid, and dicloxacillin, respectively. The method was validated in linear ranges of 2-28  µ g mL -1 , 2-35  µ g mL -1 , and 1-10  µ g mL -1 for amoxicillin, dicloxacillin, and 6-aminopenicillanic acid, respectively. The results obtained from the suggested HPLC/MS were statistically compared with those obtained from the reported HPLC method, where no significant difference appeared respecting accuracy and precision. According to the analytical eco-scale assessment method, the proposed method was proved to be greener than the reported one, where the analysis time and the amount of the wasted effluent decreased., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Atiah H. Almalki et al.)

A simple and reliable HPLC method is developed for isocratic separation of a ternary mixture of Salbutamol Sulfate (SAL), Guaifenesin (GUI) and its impurity Guaiacol (GUA) either in pure powder or in pharmaceutical formulation. Chromatographic separation was applied on a Hypersil GOLD CN column with a mobile phase consisting of 0.05 M KH2PO4 (containing 0.1% triethylamine, pH adjusted to 3.7 by phosphoric acid): methanol (60: 40 by volume) using 0.6 mL min-1 flow rate and detection of peaks at 275 nm at 25°C with run time around 6 min. The calibration plots were linear over the concentration ranges of 0.5-20, 0.5-30 and 0.1-10 μg mL-1 for SAL, GUI and GUA, respectively. ICH guidelines were used for the validation of presented method. The obtained results were compared with the results obtained from the reported HPLC method and no significant difference was found regarding accuracy and precision., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The combination of pyridoxine HCl (PYR) and doxylamine succinate (DOX) was proved to be effective and safe acting as the first line of pregnancy medication for vomiting and nausea under a trade name; Vomibreak® delayed release tablets. This combination has been available in the Egyptian market since 2016. Dissolution study is a meaningful tool that represents a predictor of output because the rate controlling steps in any drug's absorption is the rate of discharging from its medicinal formulation. Generally, the dissolution test of all delayed release tablets is operated at two stages: first the acid stage then the buffer stage. In our work, the acid stage was performed in 0.1 N hydrochloric acid (0.1 M HCl) and the buffer one was in 0.2 M sodium phosphate buffer (0.2 M Na-PB), pH = 6.8, according to FDA guidelines. In present work, for the first time, this binary mixture was quantitatively determined by applying four spectrophotometric methods. PYR was directly determined by zero order spectra method (D 0 ) at 291.0 nm in the range 2.0-26.0 μg/mL in the acid stage and at 325.0 nm in the range 5.0-35.0 μg/mL in the buffer stage, where DOX show no interference in both cases. However, DOX was determined by three methods, namely, Dual wavelength (DW), Ratio difference (RD) and Derivative ratio (DD 1 ). DD 1 was the chosen method for determination of DOX in the two-phase dissolution study of Vomibreak® tablets at 249.0 nm in the range 2.0-44.0 μg/mL and 273.0 nm in the range 5.0-100.0 μg/mL in acid and buffer phases, respectively. All of the suggested methods were tested in compliance with ICH guidelines, where all methods were found to be reliable, reproducible, and selective. A statistical comparison was computed between two analytical techniques of critical importance in the development of two media dissolution profile: proposed UV- spectrophotometric and reported HPLC methods where no significant difference was found. Difference (ƒ 1 ) and similarity (ƒ 2 ) factors were calculated for PYR and DOX and shown that ƒ 1 was 1.490 and 1.654 and ƒ 2 was 94.431 and 92.396 for PYR and DOX, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Three univariate and two multivariate spectrophotometric methods were developed and subsequently validated to determine phenazopyridine HCl (PHZ) and trimethoprim (TMP) in the presence of 2,6-Diaminopyridine (2,6-DAP). The first univariate method depends on direct determination of phenazopyridine by measuring its absorbance at 412 nm and performed in concentration range of 1.00-10.00 μg/mL. Then the contribution of phenazopyridine is removed by dividing the mixture spectrum with PHZ divisor (5 μg/mL) after that the constant is mathematically subtracted and finally the generated spectrum is multiplied with the PHZ divisor. These steps eliminate PHZ contribution and the recovered spectrum is that of TMP and 2,6-DAP only where different methods can be applied to determine TMP and 2,6-DAP through this binary mixture spectrum. The first method to determine both components depends on measuring both TMP and 2,6-DAP through their first derivative ( 1 DD) spectra at 244.70 and 259.60 nm for TMP and 2,6-DAP, respectively with concentration ranges of 4.00-24.00 μg/mL TMP and 4.00-26.00 μg/mL 2,6-DAP. The second method depends on application of the isoabsorptive method which was used for TMP determination at its isoabsorptive point with 2,6-DAP at 242.64 nm with concentration range 1.00-20.00 μg/mL for TMP. The developed univariate methods were successfully applied to determine PHZ, TMP and PHZ impurity (2,6-DAP). Two multivariate methods were applied for determination of PHZ and TMP in presence of 2,6-DAP namely, Principle Component Regression (PCR) and Partial Least Squares (PLS). The results of the two models show that simultaneous determination of PHZ and TMP in presence of PHZ impurity can be performed in the concentration ranges of 6.00-14.00 μg/mL PHZ and 24.00-56.00 μg/mL TMP. All the proposed methods were successfully applied to analyze PHZ and TMP in pharmaceutical formulations without interference from the dosage form additives and the results were statistically compared with the reported method., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The major objective of this work was to develop a portable, disposable, cost-effective, and reliable POC solid-state electrochemical sensor based on potentiometric transduction to detect benzodiazepine abuse, mainly diazepam (DZP), in biological fluids. To achieve that, microfabricated Cu electrodes on a printed circuit board modified with the conducting polymer poly(3-octylthiophene) (POT) have been employed as a substrate. This polymer was introduced to enhance the stability of the potential drift (0.9 mV/h) and improve the limit of detection (0.126 nmol mL -1 ). Nernstian potentiometric response was achieved for DZP over the concentration range 1.0 × 10 -2 to 5.0 × 10 -7  mol L -1 with a slope of 55.0 ± 0.4 mV/decade and E 0 ~ 478.9 ± 0.9. Intrinsic merits of the proposed sensor include rapid response time (11 ± 2 s) and long life time (3 months). In order to enhance the selectivity of the potentiometric sensor towards the target drug and minimize any false positive results, calix[4]arene (CX4) was impregnated as an ionophore within the PVC plastic ion-sensing membrane. The performance of the POC sensors was assessed using electrochemical methods of analysis and electrochemical impedance spectroscopy as a surface characterization tool. The studied sensors were applied to the potentiometric determination of DZP in different biological fluids (plasma, urine, saliva, and human milk) in the presence of its metabolite with an average recovery of 100.9 ± 1.3%, 99.4 ± 1.0%, 101.8 ± 1.2%, and 99.0 ± 2.0%, respectively. Graphical abstract.

Background: Imidocarb dipropionate (IMD) is an immunomodulator agent commonly used for treatment of anaplasmosis in cattle., Objective: Thus, two sensitive, specific, and precise stability-indicating chromatographic methods have been developed, optimized, and validated for its determination in presence of its acid, alkaline, and oxidative stressed degradation products., Method: The first method is based on separation of IMD and its forced induced degradation products on reversed phase cyano column using isocratic elution system consisted of sodium acetate buffer-methanol-acetonitrile (55: 30:15, v/v/v), pH 4.6 at a flow rate of 1.2 mL/min, and UV detection at 254 nm. The second method utilized TLC combined with densitometric determination of the separated bands at 254 nm. The separation was achieved using silica gel 60 F254 TLC plates with a mixture of ethyl acetate-methanol-ammonia-water (8.5:1:0.5:0.2, v/v/v/v) as a developing system., Results: HPLC analysis was applied in range of 0.25-40 µg/mL with LOD of 0.073 µg/mL. While densitometric measurements showed linearity in the range of 0.1-1.8 µg/band with LOD of 0.02 µg/band., Conclusions: The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of IMD in its commercial veterinary formulations with good recoveries. Furthermore, the proposed HPLC method was extended to the determination of IMD residues in bovine meat and milk samples., Highlights: Bovine meat, HPLC, Imidocarb dipropionate, Milk, TLC., (© AOAC INTERNATIONAL 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Two robust and selective stability-indicating chromatographic methods were developed and validated for the determination of metolazone in drug substance and pharmaceutical dosage form in the presence of its degradation products. The HPLC method employed a Kromasil C18 (250 × 4.6,5 μm) column and a mobile phase of acetonitrile: 0.2% orthophosphoric acid (32:68 v/v) at a flow rate 2 mL/min and detection at 238 nm. The separation was performed in HPLC isocratic mode. The robustness of the suggested method was assessed using the Plackett-Burman design, parameters affecting system suitability were established and non-significant intervals for the significant parameters were considered. The HPTLC method employed Nano-SIL-20 UV254 HPTLC plates as adsorbent, ethyl acetate: toluene: acetic acid solution (4:4:0.5, v/v/v), as a developing solvent system and densitometric detection at 238 nm. Metolazone was exposed to different stress conditions, including acid and alkaline hydrolysis and oxidative and photolytic degradation. The main degradation products obtained have been characterized and interpreted based on LC-MS. The linearity of the suggested methods was proved in the concentration range of 20-75 μg/mL for the HPLC method and 100-900 ng/spot for the HPTLC method. The suggested methods were validated according to international conference on harmonization guidelines. These methods were successfully dedicated for the estimation of metolazone in drug substance and pharmaceutical dosage form in the presence of its degradation products. The results of the suggested methods were evaluated and compared statistically with results obtained by an official method without finding any significant difference., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Three chromatographic methods were developed, optimized and validated for Paracetamol (PAR), Orphenadrine citrate (Or.cit) and Caffeine (CAF) determination in their mixture and in presence of PAR toxic impurity; P-aminophenol (PAP) in tablets. The first method is based on a thin layer chromatography combined with densitometry. Separation was achieved using silica gel 60 F254 TLC plates and dichloromethane:methanol:acetone:glacial acetic acid (9:1:0.5:0.3, v/v/v) as a developing system at 230 nm. The second method is based on high-performance liquid chromatography with diode array detection. The proposed compounds are separated on a reversed phase C18 analytical column using phosphate buffer (pH 9; 0.05 M) and methanol (80:20, v/v) at 1.2 mL/min. Linear regressions are obtained in the range of 1-500 μg/mL, 25-1000 μg/mL and 1-400 μg/mL for PAR, Or.cit and CAF, respectively. Quantification of the toxic PAP is carried out using LC-MS-MS by electrospray ionization in the positive mode using triple quadrupole mass spectrometry. The limit of quantification for PAP is 1 ng/mL. All methods are validated according to the ICH guidelines and successfully applied to determine PAR, Or.cit, CAF and PAP in pure powder and in combined tablets dosage form without interference from excipients., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Neuromuscular blocker agent namely; Vecuronium bromide (VEC) was quantified through developing a simple reversed phase liquid chromatographic (RP-LC) method, in drug substance and in drug product. The proposed method could quantify VEC in the presence of its degradation products produced from exposing VEC to different stress conditions as recommended by the International Conference on harmonization (ICH) guidelines. Acidic (2M HCl), basic (2MNaOH) hydrolysis, oxidation (3% H 2 O 2 ), photolysis (UV light at 254nm), and thermal (135 °C) degradation were estimated by exposing the drug substances to different stress conditions. The separation of the drug from its degradation products was successfully conducted on Tracer Extrasil CN (150 × 4.6mm; 5μm) column using O-phosphoric acid (pH6; 0.05M)-acetonitrile (50:50v/v) as mobile phase. The detection and quantification was done with UV detection at210nm.The validation data were found to be acceptable over a concentration range10-120 μg/ml. The limit of quantification (LOQ) and detection (LOD) were 8.10 and 2.67 μg/ml, respectively. The proposed method met all criteria for validation in accordance with the International Conference on harmonization (ICH) guidelines. The presented work monitored the degradation profile for VEC under various stress conditions and provided a simple LC method for its routine analysis. The structures of the forced degradation products had been described in details using the MS data and the possible degradation pathways were outlined. Besides, the results obtained from the developed method compared statistically with that of the official method indicting high accuracy and precision., (© 2020 Published by Elsevier Ltd.)

Reasons for formulation instability were investigated either encountered during production or analytical processes of azilsartan medoxomil (AZM)/chlorthalidone hydrochloride (CLT) tablets. Through the identification of the most feasible degradation pathways, several strategies were proposed to enhance the stability of AZM/CLT formulation. Furthermore, a robust HPLC-UV method was developed and validated for the determination of AZM, CLT in the presence of their possible degradation products. For chromatographic method development, typical quality by design (QbD) approach was implemented. In order to optimize fourteen chromatographic responses, we have used a central composite design with four factors (pH, temperature, flow rate, and acetonitrile %). However, the developed method provides a design space, but optimum parameters were Inertsil C8 column (150 x 4.6 mm, 5 μm), mobile phase composed of 0.025 M phosphate buffer pH 2.7 and acetonitrile (52.5: 47.5%), with flow rate of 1.5 mL.min -1 and detection wavelength 225 nm at 33 °C. The method was then validated according to ICH guidelines and applied to quantitate AZM and CLT in the pharmaceutical formulation. To the best of our knowledge, this manuscript is the first attempt to discuss such instability issues, to propose strategies that enhance the stability of AZM/CLT tablet formulation, to develop robust stability-indicating method taking into consideration the realistic degradation products in addition to minor ones., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: The utilization of selection methods such as genetic algorithm (GA) aims to construct better partial least squares (PLS) and principal component regression (PCR) models than those established from the full-spectrum range., Objective: Determination of paracetamol (PAR), orphenadrine citrate (Or.cit), and caffeine (CAF) in the presence of PAR nephrotoxic impurity [p-aminophenol (PAP)]. GA was applied to select the optimum wavelengths used., Methods: A calibration set was prepared in which the three drugs, together with PAP, were modeled by multilevel multifactor design. This calibration set was used to build the PLS and PCR models, either with or without preprocessing the data using GA., Results: Results were compared with and without preprocessing, and this revealed that GA can find an optimized combination of spectral wavelengths, yielding a lower root mean square error of prediction as well as a lower number of latent variables used. The results of the two models show that simultaneous determination of the aforementioned drugs can be performed in the concentration ranges of 20-60, 3-11, and 1-9 μg/mL for PAR, Or.cit, and CAF, respectively., Conclusions: The proposed models were applied for the determination of the three drugs in their pharmaceutical formulations, and the results were verified by the standard addition technique., Highlights: GA can be useful as a wavelength selection tool before applying multivariate PLS and PCR methods. GA gives an improvement in the predictive ability of the models with lower RMSEP and less number of latent variables (LVs). The proposed PLS, PCR, GA-PLS, and GA-PCR spectrophotometric methods were able to determine paracetamol, orphenadrine citrate, and caffeine in the presence of p-aminophenol and severe spectral overlapping., (© AOAC INTERNATIONAL 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Eptifibatide (EPT) is a cyclic heptapeptide derived from a protein found in the venom of the south-eastern pygmy rattle snake used as an antiplatelet drug. In this study, a newly developed HPLC method demonstrating no interference from the different degradation products of EPT has been optimized and validated. The method was based on HPLC separation of eptifibatide from its degradation products using reversed phase C18 column at ambient temperature with mobile phase consisting of acetonitrile: 50 mM sodium dihydrogen orthophosphate dihydrate, pH was adjusted to 2.2 with orthophosphoric acid (25:75 v/v). Quantitation was achieved with UV detection at 220 nm based on peak area. The proposed method was validated according to the ICH guidelines and applied to evaluate the stability of EPT under different stress conditions including temperature, oxidation and hydrolysis over wide pH range (2-10). Moreover, kinetic study of EPT oxidation and its hydrolysis at pH 10 was demonstrated. The proposed method was successfully applied to quantify EPT in bulk powder and in pharmaceutical formulation with a runtime shorter than all the reported methods., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Two sensitive chromatographic methods have been developed, and validated for chlorpheniramine maleate (CM), phenylephrine (PE) and guaifenesin (GF) determination in their mixture and in presence of GF related substance guaiacol (GL) and preservative namely; sodium benzoate (NaB). The first method was based on thin layer chromatographic separation (TLC) followed by densitometric determination of the separated spots. The separation was achieved using silica gel 60 F254 TLC plates and ethyl acetate: methanol: toluene: ammonia (7:1.5:1:0.5, by volume) as a developing system. Densitometric quantification of the three drugs was carried by the reflectance mode at 270 nm. The second method was based on the use of high-performance liquid chromatography with diode array detection, by which the proposed components were separated on a reversed phase C18 analytical column using phosphate buffer pH 2.9 (containing 0.1 g Heptane-1-sulphonic acid sodium salt) and acetonitrile (85:15, v/v) at 0.8 mL/min for 4 minutes then 1 mL/min till end of the run using flow rate online switching technique. Both methods were validated according to the ICH guidelines and successfully applied for the determination of CM, PE, and GF in pure powder and in combined cough syrup without interference from the excipients., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Rocuronium bromide (ROC) is currently regarded as the 'gold-standard' in emergency medicine and anesthesia. Globally, millions of human beings are daily administered ROC at emergency settings where it is favored among all the neuromuscular blockers, particularly succinylcholine, for both its fast onset of action and short duration. However, it has been reported that 45% of patients in the post-anesthesia care unit are susceptible to residual postoperative paralysis, undesired ventilator effects and incomplete recovery after ROC administration. From an analytical chemistry perspective, direct determination of ROC is a difficult approach due to the complexity in isolation from biological specimens as well as the lack of a sensitive detection techniques and detectable chromophore. This contribution describes the development of a calix[6]arene-based screen-printed electrode (SPE) that is capable of ROC detection in biological samples at the point of care. This fabricated SPE (sensor 1) exhibited superior performance characteristics (slope, LOD and life time) with respect to an ionophore-free liquid-contact electrode, LCE, (sensor 2). The proposed SPE showed a linear response over a concentration from 1 µM to 10 mM, with a Nernstian slope of 57.9 mV/decade and a detection limit of 0.39 µM. Moreover, this sensor showed a considerable selectivity towards ROC in presence of the anticipated interfering ions. To investigate the ability of the SPE to detect ROC in real biological specimens, ROC has been spiked at a concentration comparable to its anticipated level in human plasma (C max ~ 40 µM) and the proposed SPE displayed an excellent platform for therapeutic drug monitoring (TDM) of ROC with respect to UV-spectrophotometry and LC/MS. Finally, the developed SPE was used for the determination of ROC in its commercial pharmaceutical formulation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Traditional methods for Lomefloxacin hydrochloride (LOM) determination involve pretreatment steps, which extend analysis time and use hazardous chemicals. Objective: The ability to provide a rapid route without sample pretreatment for quantitative determination of compounds via a low-cost instrument is a challenging task. In this work, a simple potentiometric method was developed to determine the antibacterial LOM via in-house fabricated ion selective electrodes. Methods: Different sensors were fabricated using a poly vinyl chloride-based membrane, potassium tetrakis(4-chlorophenyl) borate as a cation exchanger, and 2-Nitrophenyl octyl ether as a plasticizer (sensor 1). To increase the selectivity of sensor 1, a selective molecular recognition component 2-hydroxypropyl-β-cyclodextrin was used as ionophore (sensor 2). Results: The proposed method was validated according to International Union of Pure and Applied Chemistry recommendations, in which the proposed sensors show a linear dynamic range from 1 × 10 -5 to 1 × 10 -2 mol/L, with Nernstian slopes of 55.829 and 58.229 mV/decade for sensors 1 and 2, respectively. It was applied to determine LOM in bulk powder, in different dosage forms, and in plasma with no sample pretreatment. Also, the suggested method can be used as a green, in-line bench top real-time analyzer for in-process monitoring of LOM release from its tablets, under U.S. Food and Drug Administration dissolution regulations, with clear discrimination from common excipients. Results obtained by the proposed potentiometric method were compared with those obtained by a reported HPLC method. Conclusions: The proposed method is considered as a perfect alternative to traditional reported methods for LOM determination.

Background: Oxyclozanide (OXY) is a veterinary medicine used for control of fascioliasis in farm animals. Literature review shows absence of sufficient information regarding its stability. Such information is important as it affects many stages of a drug's life cycle, from pharmaceutical manufacturing to its environmental fate understanding of the degradation of the drug once it is placed in the environment. Objective: An HPLC method was developed to address the impact of different stress conditions on OXY's stability. Methods: OXY's stability was investigated by exposure to forced acid and alkaline hydrolysis, thermal, oxidative and photolytic degradation, which are different stress conditions applied to the forced degradation study. Separation was performed on Eurosphere C18 analytical column (125 × 4.6 mm, 5 μm particle size) using 50 mM sodium acetate trihydrate (pH 4.5) and acetonitrile (50:50, v/v) as mobile phase and UV detection at 254 nm. A photolytic kinetics study was conducted by monitoring OXY photolysis under monochromatic and polychromatic light sources (UV lamp at 366 nm and natural sunlight) in aqueous buffers of different pHs (5, 7, and 9). LC-MS was used to identify the major photolytic degradate. Results: OXY was quantified over a concentration range of 1-80 μg/mL with mean recovery of 99.32 ± 1.80%. The drug was susceptible to oxidative and photolytic degradation. The photolytic kinetics were pH dependent. The LC-MS result supported photo-dehalogenation degradation mechanism. Conclusions: The developed method could be used in OXY stability testing. The results of the photolytic kinetics study can address OXY aquatic photo-transformation, thereby predicting its environmental fate and risks imposed on the ecosystem. Highlights: An HPLC method was developed for monitoring OXY degradation behavior and studying its photolytic kinetics with identification of its photodegradate.

A spectrofluorimetric method for the determination of eptifibatide is presented based on its native fluorescence. The type of solvent and the wavelength of maximum excitation and emission were carefully selected to optimize the experimental conditions. Under the specified experimental conditions, the linearities obtained between the emission intensity and the corresponding concentrations of eptifibatide were in the range 0.1-2.5 μg/ml for the calibration curve constructed for direct determination of eptifibatide in dosage form and 0.05-2.2 μg/ml for the calibration curve constructed in spiked human plasma with a good correlation coefficient (r > 0.99). The lower limit of quantification for the calibration curve constructed in human plasma was 0.05 μg/ml. Recovery results for eptifibatide in spiked plasma samples and in dosage form, represented as mean ± % RSD, were 95.17 ± 1.94 and 100.29 ± 1.33 respectively. The suggested procedures were validated according to the International Conference on Harmonization (ICH) guidelines for the direct determination of eptifibatide in its pure form and dosage form and United States Food and Drug Administration (US FDA) Guidance for Industry, Bioanalytical Method Validation for the assay of eptifibatide in human plasma., (© 2018 John Wiley & Sons, Ltd.)

Traditional Partial Least Squares (PLS) and Advanced Artificial Neural Network (ANN) models were applied for the quantitative determination of paracetamol (PAR) and chlorzoxazone (CZX) together with their process-related impurities namely; 4-aminophenol (AP), 4‑chloroacetanilide (AC), 4‑nitrophenol (NP), 4‑chlorophenol (CP) and 2‑amino-4-chlorophenol (ACP). Both models were applied first to full spectrum data then the results were compared to those obtained after wavelength selection using Genetic Algorithm (GA). A 5-level 7-factor experimental design was used giving rise to 25 mixtures containing different proportions of the seven compounds. The calibration set was composed of 15 mixtures while 9 mixtures were used in the validation set to test the predictive ability of the suggested models. The four models PLS, ANN, GA-PLS and GA-ANN were successfully applied for the determination of PAR and CZX in their pure and pharmaceutical dosage form. One way ANOVA was carried out between the developed methods and the official ones for PAR and CZX and no significant difference was found. The four models can be easily applied for the determination of the selected drugs in quality control laboratories lacking expensive HPLC instruments., (Copyright © 2018 Elsevier B.V. All rights reserved.)