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A simple and facile microwave-assisted method was developed for the synthesis of highly fluorescent silver-nanoparticles (Ag-NPs). The synthesis of silver-nanoparticles depends on a redox reaction between silver nitrate and ascorbic acid using chitosan as a stabilizing agent. The produced Ag-NPs were characterized using Zeta potential and transmission electron microscope micrograph where they are spherical in shape with smooth surface morphology and size of 26.81 ± 2.2 nm. Favipiravir (FAV) was found to cause an obvious enhancement in the fluorescence of Ag-NPs; hence, they were used for its spectrofluorimetric estimation. The fluorescence intensity was measured at 430 nm after excitation at 360 nm. Under optimum conditions, a good linear relationship was accomplished between the FAV concentration and the fluorescence intensity in a range of (5.0-200.0) ng/mL with a limit of detection of 1.59 ng/mL. The method was successfully applied for the assay of the drug in its commercial tablets and spiked human plasma samples, and the results obtained were satisfactory., (© 2024. The Author(s).)

A green and simple UPLC method was developed and optimized, adopting a factorial design for simultaneous determination of oseltamivir phosphate and remdesivir with dexamethasone as a co-administered drug in human plasma and using daclatasvir dihydrochloride as an internal standard within 5 min. The separation was established on UPLC column BEH C 18 1.7 μm (2.1 × 100.0 mm) connected to UPLC pre-column BEH 1.7 μm (2.1 × 5.0 mm) at 50 °C with an injection volume of 10 μL. The photodiode array detector (PDA) was set at three wavelengths of 220, 315, and 245 nm for oseltamivir phosphate, the internal standard, and both dexamethasone and remdesivir, respectively. The mobile phase consisted of methanol and ammonium acetate solution (40 mM) adjusted to pH 4 in a ratio of 61.5:38.5 (v/v) with a flow rate of 0.25 mL min -1 . The calibration curves were linear over 500.0-5000.0 ng mL -1 for oseltamivir phosphate, over 10.0-500.0 ng mL -1 and 500.0-5000.0 ng mL -1 for dexamethasone, and over 20.0-500 ng mL -1 and 500.0-5000.0 ng mL -1 for remdesivir. The Gibbs free energy and Van't Hoff plots were used to investigate the effect of column oven temperatures on retention times. Fluoride-EDTA anticoagulant showed inhibition activity on the esterase enzyme in plasma. The proposed method was validated according to the M10 ICH, FDA, and EMA's bioanalytical guidelines. According to Eco-score, GAPI, and AGREE criteria, the proposed method was considered acceptable green., (© 2024. The Author(s).)

One of the most common features of many different clinical conditions is pain; hence, there is a crucial need for eliminating or reducing it to a tolerable level to retrieve physical, psychological and social functioning. A first derivative synchronous spectrofluorimetry technique is proposed for the simultaneous determination of celecoxib and tramadol HCl, a recent coformulation authorized for treating acute pain in adults. The method includes using synchronous spectrofluorimetry at ∆λ = 80 nm where tramadol HCl was determined using first derivative technique at λ = 230.2 nm, while celecoxib was determined at λ = 288.24 nm. The proposed method was successfully applied to their co-formulated dosage forms in addition to spiked human plasma and validated in agreement with the guidelines of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH). The linear ranges were found to be 0.50-5.0 and 0.15-0.50, the limits of detection to be 0.088 and 0.011 and the limits of quantification to be 0.266 and 0.032 μg/ml for celecoxib and tramadol, respectively. Statistical analysis revealed no significant difference when compared with previously reported methods as evidenced by the values of the variance ratio F-test and Student t-test. The proposed method was successfully applied to commercial dosage forms and spiked human samples. Moreover, the greenness of the proposed method was investigated based on the analytical eco-scale approach, with the results showing an excellent green scale with a score of 95., (© 2024 John Wiley & Sons Ltd.)

A simple and facile microwave-assisted method was developed for the synthesis of highly fluorescent nitrogen-doped carbon quantum dots (N-CQDs) using sucrose and urea. The produced quantum dots exhibited a strong emission band at 376 nm after excitation at 216 nm with quantum yield of 0.57. The as-prepared N-CQDs were characterized using Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) images, and ultraviolet-visible (UV-visible) spectra. The average particle size was 7.7 nm. It was found that torsemide (TRS) caused an obvious quenching of the fluorescent N-CQDs; so, they were used for its spectrofluorometric estimation. An excellent linear correlation was found between the fluorescence quenching of N-CQDs and the concentration of the drug in the range of 0.10 to 1.0 μg/mL with limit of quantitation (LOQ) of 0.08 μg/mL and limit of detection (LOD) of 0.027 μg/mL. The method was successfully applied for the assay of the drug in its commercial tablets and spiked human plasma samples, and the results obtained were satisfactory. Complex GAPI was used for greenness assessment of the analytical procedures and the pre-analysis steps. Interference likely to be introduced from co-administered drugs was also studied., (© 2024 John Wiley & Sons Ltd.)

The study of the intermolecular binding interaction of small molecules with DNA can guide the rational drug design with greater efficacy and improved or more selective activity. In the current study, nintedanib's binding interaction with salmon sperm DNA (ssDNA) was thoroughly investigated using UV-vis spectrophotometry, spectrofluorimetry, ionic strength measurements, viscosity measurements, thermodynamics, molecular docking, and molecular dynamic simulation techniques under physiologically simulated conditions (pH 7.4). The obtained experimental results showed that nintedanib and ssDNA had an apparent binding interaction. Nintedanib's binding constant ( K b ) with ssDNA, as determined using the Benesi-Hildebrand plot, was 7.9 × 10 4 M -1 at 298 K, indicating a moderate binding affinity. The primary binding contact forces were hydrophobic and hydrogen bonding interactions, as verified by the enthalpy and entropy changes ( ΔH 0 and ΔS 0 ), which were - 16.25 kJ.mol -1 and 39.30 J mol -1 K -1 , respectively. According to the results of UV-vis spectrophotometry, viscosity assays, and competitive binding interactions with ethidium bromide or rhodamine B, the binding mode of nintedanib to ssDNA was minor groove. Molecular docking and molecular dynamic simulation studies showed that nintedanib fitted into the B-DNA minor groove's AT-rich region with high stability. This study can contribute to further understanding of nintedanib's molecular mechanisms and pharmacological effects.

Background: The increased use of cephalosporin antibiotics in the last few years as well as the detection of their residues in wastewater treatment plants and hospital wastewater poses a risk for infiltration of their residues into environmental water samples., Objective: A simplified, sensitive, and convenient solid-phase extraction (SPE) procedure coupled with either HPLC or fast HPLC methods with diode array detection was developed and validated to screen the residues of six different cephalosporin antibiotics: cefoperazone, cefipime, ceftazedime, ceftriaxone, cefdinir, and cefotaxime, along with amoxicillin, levofloxacin, and ciprofloxacin in water samples., Methods: An HPLC-diode array detector (HPLC-DAD) method and a fast HPLC method, based on a core-shell stationary phase, were developed for the fast screening of the antibiotic compounds. In addition, the SPE step was optimized to enable the extraction of the studied drugs with high accuracy of the recovered amounts of residues., Results: The method sensitivity was enhanced by the coupling of SPE with HPLC-DAD and fast HPLC to achieve low LODs; from 0.2 to 3.8 ng/mL and from 0.65 to 12.2 ng/mL, respectively. The developed methods were augmented by LC-MS/MS determination for confirmation of identity and quantity of any positively identified sample. The method was applied to the analysis of water samples collected from a rural site. In Addition, an example application of cleaning validation of cefotaxime-contaminated stainless-steel surfaces was provided., Conclusion: The method's simplicity and high sensitivity encourage its application in monitoring of antibiotic residues in different types of water samples such as environmental samples and samples from cleaning validation activities., Highlights: HPLC-DAD and fast HPLC methods were developed for separation of nine different antibiotics. The combination with the SPE procedure achieved low detection limits; from 0.2 to 3.8 ng/mL for SPE-HPLC-DAD and from 0.65 to 12.2 ng/mL for SPE-fast HPLC., (© The Author(s) 2023. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Solid phase extraction (SPE) techniques, based on computationally designed magnetic-based multi-targeting molecular imprinted polymer (MT-MIP), combined with UV spectrophotometric approaches provide advantages in the examination of counterfeit samples., Objective: The current work describes an innovative and sustainable methodology for the simultaneous determination of tadalafil (TAD) and dapoxetine hydrochloride (DAP) in aphrodisiac counterfeit products (honey and instant coffee) utilizing SPE exploiting MT-MIP. Additionally, an innovative UV spectrophotometric method capable of resolving TAD in its pharmaceutical binary mixtures with DAP was developed. A novel computational approach was implemented to tailor the synthesis and design of the MT-MIP particles., Methods: We applied a newly developed UV spectrophotometric method which was based on a Fourier self-deconvolution (FSD) method coupled with the isoabsorptive point for determination of TAD and DAP in pharmaceutical dosage form. We also applied an SPE process based on MT-MIP designed particles, assisting in the analysis of both drugs in counterfeit food samples. The SPE process and the UV spectroscopic methodology were assessed regarding their greenness using the pioneering green analytical procedure index (GAPI), analytical greeness including sample preparation (AGREEprep) and AGREE tools. The synthesized MT-MIP particles were characterized by scanning electron microscopy and energy-dispersive x-ray spectroscopy., Results: The suggested spectrophotometric methods revealed a wide linear concentration range of 2-50 µg/mL with lower LODs in the range of 0.604-0.994 µg/mL. Additionally, the suggested method demonstrated the utmost sensitivity and eco-friendliness for their target in its mixed dosage form and counterfeit food products., Conclusion: The SPE process and the developed analytical UV spectroscopic methodology were validated as per the ICH guidelines, and were found to be suitable for overseeing some counterfeiting activities in commercially available honey and instant coffee aphrodisiac products., Highlights: An SPE method based on MT-MIP magnetic-based polymer and a UV spectroscopic method were successfully developed for analysis of TAD and DAP in different matrices., (© The Author(s) 2023. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Highly fluorescent nitrogen doped carbon quantum dots (N-CQDs) were prepared by a single-step method based on microwave heating of cane sugar and urea. The produced N-CQDs were applied as nano-sensors for the spectrofluorimetric determination of eplerenone and spironolactone. A strong emission band at 376 nm was obtained after excitation at 216 nm due to the produced N-CQDs. The native fluorescence of N-CQDs was obviously quenched upon adding increased concentrations of each drug. A strong correlation was found between the fluorescence quenching of N-CQDs and the concentration of each drug. The method was found to be linear over the range of 0.5 to 5.0 μg/mL for eplerenone and 0.5 to 6.0 μg/mL for spironolactone with LOQ of 0.383 μg/mL and 0.262 μg/mL. The developed method was further extended for determination of both drugs in their pharmaceutical tablets and spiked human plasma. The results obtained were statistically compared with those of reported methods. The mechanism of fluorescence quenching of N-CQDs by the two drugs was discussed., (© 2023. The Author(s).)

Background: Cannabis has a long history of being credited with centuries of healing powers for millennia. The cannabis plant is a rich source of cannabinoids and terpenes. Each cannabis chemovar exhibits a different flavor and aroma, which are determined by its terpene content. Methods: In this study, a gas chromatography-flame ionization detector method was developed and validated for the determination of the 10 major terpenes in the main three chemovars of Cannabis sativa L. with n -tridecane used as the internal standard following the standard addition method. The 10 major terpenes (monoterpenes and sesquiterpenes) are α-pinene, β-pinene, β-myrcene, limonene, terpinolene, linalool, α-terpineol, β-caryophyllene, α-humulene, and caryophyllene oxide. The method was validated according to Association of Official Analytical Chemists guidelines. Spike recovery studies for all terpenes were carried out on placebo cannabis material and indoor-growing high THC chemovar with authentic standards. Results: The method was linear over the calibration range of 1-100 μg/mL with r 2 >0.99 for all terpenes. The limit of detection and limit of quantification were calculated to be 0.3 and 1.0 μg/mL, respectively, for all terpenes. The accuracy (%recovery) at all levels ranged from 89% to 104% and 90% to 111% for placebo and indoor-growing high THC chemovar, respectively. The repeatability and intermediate precision of the method were evaluated by the quantification of target terpenes in the three different C. sativa chemovars, resulting in acceptable relative standard deviations (less than 10%). Conclusions: The developed method is simple, sensitive, reproducible, and suitable for the detection and quantification of monoterpenes and sesquiterpenes in C. sativa biomass.

This study uses a liquid chromatography-electrospray ionization-tandem mass spectrometry method to determine β-Sitosterol and Ferulic acid in Pygeum africanum extract. Chromatographic separation of the two analytes was performed on an ACQUITY UPLC H-Class system coupled with Xevo TQD mass spectrometer and HSS T3 C18 column (2.1 X 50 mm, 1.8 μm). Mobile phase A consisted of an aqueous solution of 0.1% formic acid (v/v), and mobile phase B was 0.1% formic acid (v/v) in methanol pumped through a gradient elution mode. Mass spectrometer parameters were optimized using an electrospray ionization source in the positive and negative ionization modes. The quantification of the two analytes was performed using multiple reaction monitoring transitions. The method was fully validated per (FDA) guidelines regarding linearity, accuracy, precision, carryover and selectivity. The proposed method was applied successfully to determine the two investigated compounds in commercially available pharmaceutical products., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Greenness-by-design (GbD) is an approach that integrates green chemistry principles into the method development stage of analytical processes, aiming to reduce their environmental impact. In this work, we applied GbD to a novel univariate double divisor corrected amplitude (DDCA) method that can resolve a quaternary pharmaceutical mixture in a fixed-dose polypill product. We also used a genetic algorithm as a chemometric modeling technique to select the informative variables for the analysis of the overlapping mixture. This resulted in more accurate and efficient predictive models. We used a computational approach to study the effect of solvents on the spectral resolution of the mixture and to minimize the spectral interferences caused by the solvent, thus achieving spectral resolution with minimal analytical effort and ecological footprint. The validated methods showed wide linear concentration ranges for the four components (1-30 µg/mL for losartan, 2.5-30 µg/mL for atorvastatin and aspirin, and 2.5-35 µg/mL for atenolol) and achieved high scores on the hexagon and spider charts, demonstrating their eco-friendliness., (© 2023 Deutsche Pharmazeutische Gesellschaft.)

A facile, simple, green and sensitive spectrofluorometric method was developed for determination of the calcimimetic drug cinacalcet hydrochloride. It is used for the treatment of hyperparathyroidism. The drug showed high native fluorescence intensity at 320 nm after excitation at 280 nm. The method was linear over the range of 5.0-400.0 ng ml -1 with excellent correlation (R 2 = 0.9999). Limit of detection (LOD) and limit of quantitation (LOQ) values were 1.19 and 3.62 ng ml -1 , respectively. The percentage recovery was found to be 100.42% ± 1.39 (n=8). The proposed method was successfully applied for determination of cinacalcet in spiked human plasma samples with % recoveries of (87.23 to 109.69%). Two recent greenness metrics (GAPI and Analytical Eco-Scale) were chosen to prove the eco-friendly nature of the method. Furthermore, the proposed method was successfully applied to dissolution study of commercial cinacalcet tablets. The interference likely to be introduced by some commonly co-administrated drugs such as metoprolol and itraconazole was studied; the tolerance limits were calculated., (© 2023 IOP Publishing Ltd.)

Food and Drug Administration (FDA) recently approved co-formulated celecoxib and tramadol for the treatment of acute pain in adults. Three spectrophotometric methods were efficiently applied to estimate the co-formulated Celecoxib and Tramadol in their tablets; second derivative 2D-spectrophotometry technique (method I), induced dual-wavelength technique (method II) and dual-wavelength resolution technique (method III). The proposed methods were successfully validated following the International Council for Harmonisation (ICH) guidelines and statistically assessed based on the correlation coefficients, relative standard deviations as well as detection and quantitation limits. The obtained results revealed non-significant differences compared to the reported results as revealed by the variance ratio F test and Student t test. Moreover, the applied techniques were further assessed concerning their greenness based on the analytical eco-scale method revealing an excellent green scale with a final score of 95. The proposed spectrophotometric techniques could be applied for the routine analysis and quality control of the studied drugs in their dosage form., (© 2023. The Author(s).)

A green, rapid, and simple RP-UPLC method was developed and optimized by full factorial design for the simultaneous separation of oseltamivir phosphate, daclatasivir dihydrochloride, and remdesivir, with dexamethasone as a co-administered drug. The separation was established on a UPLC column BEH C 18 1.7 µm (2.1 × 100.0 mm) connected with a UPLC pre-column BEH 1.7 µm (2.1 × 5.0 mm) at 25 °C with an injection volume of 10 µL. The detector (PDA) was set at 239 nm. The mobile phase consisted of methanol and ammonium acetate (8.1818 mM) in a ratio of 75.7: 24.3 (v/v). The flow rate was set at 0.048 mL min -1 . The overall separation time was 9.5 min. The retention times of oseltamivir phosphate, dexamethasone, daclatasivir dihydrochloride, and remdesivir were 6.323 ± 0.145, 7.166 ± 0.036, 8.078 ± 0.124, and 8.572 ± 0.166 min (eight replicates), respectively. The proposed method demonstrated linearity in the ranges of 10.0-500.0 (ng mL -1 ) and 0.5-30.0 (µg mL -1 ) for oseltamivir phosphate, 50.0-5000.0 (ng mL -1 ) for dexamethasone, 25.0-1000.0 (ng mL -1 ) and 0.5-25.0 (µg mL -1 ) for daclatasvir dihydrochlorde, and 10.0-500.0 (ng mL -1 ) and 0.5-30.0 (µg mL -1 ) for remdesivir. The coefficients of determination (R 2 ) were greater than 0.9999, with percentage recoveries greater than 99.5% for each drug. The limits of quantitation were 6.4, 1.8, 7.8, and 1.6 ng mL -1 , and the limits of detection were 1.9, 0.5, 2.0, and 0.5 ng mL -1 for oseltamivir phosphate, dexamethasone, daclatasivir dihydrochloride, and remdesivir, respectively. The proposed method was highly precise, as indicated by the low percentage of relative standard deviation values of less than 1.2% for each drug. The average content and uniformity of dosage units in the studied drugs' dosage forms were determined. The average contents of oseltamivir phosphate, dexamethasone, daclatasivir dihydrochloride, and remdesivir were nearly 93%, 102%, 99%, and 95%, respectively, while the uniformity of dosage unit values were nearly 92%, 102%, 101%, and 97%. Two novel methods were established in this work. The first method was used to assess the stability of standard solutions. This novel method was based on the slope of regression equations. The second was to evaluate the excipient's interference using an innovative instrumental standard addition method. The novel instrumental standard addition method was performed using the UPLC instrument program. It was more accurate, sensitive, time-saving, economical, and eco-friendly than the classic standard addition method. The results showed that the proposed method can estimate the tested drugs' concentrations without interference from their dosage form excipients. According to the Eco-score (more than 75), the Green Analytical Procedure Index (GAPI), and the AGREE criteria (total score of 0.77), the suggested method was considered eco-friendly., (© 2023. The Author(s).)

Background: Carbon quantum dots (CQDs) are new class of carbon nanoparticles. Recently, they have been widely used as fluorescent probes due to their easy accessibility, optical properties and chemical inertness. Many available precursors are used in the synthesis of carbon quantum dots. The electrical and optical properties of CQDs could be enhanced by doping hetero atoms such as nitrogen or sulfur into their structure., Objective: The current work presents the synthesis and characterization of water-soluble nitrogen doped carbon quantum dots (N-CQDs) and their use as fluorescent nano-sensors for the spectrofluorimetric determination of furosemide in its pharmaceutical preparations and spiked human plasma., Methods: A domestic microwave was used to prepare the N-CQDs by heating a solution of sucrose and urea till complete charring (about ten minutes). The produced N-CQDs exhibit a strong emission band at 376 nm after excitation at 216 nm. Furosemide caused a quantitative quenching in the fluorescence intensity of the produced N-CQDs., Results: The proposed method was validated according to ICH Guidelines. The method was found to be linear over the range of 0.1-1.0 µg/mL with LOQ of 0.087 µg/ml., Conclusion: Ecofriendly nano fluorescent sensors (N-CQDs) were successfully synthesized. The size of N-CQDs was distributed in the range of 6.63 nm to 10.23 nm with an average of 8.2 nm. The produced N-CQDs were used as fluorescent probes for the estimation of furosemide in its pharmaceutical preparations as well as spiked human plasma samples., (© 2023. The Author(s).)

Telmisartan (TEL) and Nebivolol (NEB) are frequently co-formulated in a single dosage form that is frequently prescribed for the treatment of hypertension, moreover, telmisartan is currently proposed to be used to treat COVID19-induced lung inflammation. Green rapid, simple, and sensitive synchronous spectrofluorimetric techniques for simultaneous estimation of TEL and NEB in their co-formulated pharmaceutical preparations and human plasma were developed and validated. Synchronous fluorescence intensity at 335 nm was used for TEL determination (Method I). For the mixture, the first derivative synchronous peak amplitudes (D 1 ) at 296.3 and 320.5 nm were used for simultaneous estimation of NEB and TEL, respectively (Method II). The calibration plots were rectilinear over the concentration ranges of 30-550 ng/mL, and 50-800 ng/mL for NEB and TEL, respectively. The high sensitivity of the developed methods allowed for their analysis in human plasma samples. NEB`s Quantum yield was estimated by applying the single-point method. The greenness of the proposed approaches was evaluated using the Eco-scale, National Environmental Method Index (NEMI), and Green Analytical Procedure Index (GAPI) methods., (© 2023. The Author(s).)

Adsorbents composed of polyaniline nanostructures or their derivatives immobilized on magnetic nanoparticles had gained increasing interest for application in dispersive micro-solid phase extraction. However, reproducible binding between polymeric PANI nanopaterials and magnetic nanomaterials are still a challenging task. Furthermore, other challenges are the enhancement of physical and chemical stability of adsorbent magnetic nanoparticles as well as improvement of polymeric PANI nanoparticles selectivity towards target analytes. This work described the reproducible preparation of a nanocomposite of aniline-anthranilic acid co-polymeric nanorods with silica coated magnetite nanoparticles by physical mixing of its basic components. The prepared nanocomposite had proven stability against chemical and atmospheric attack. The formed nanocomposite in this work had advantages regarding stability and selectivity towards fluoroquinolones as compared with analogues prepared from polyaniline polymers and/or uncoated magnetite nanoparticles. The selectivity of the formed adsorbent was further optimized for microextraction of four fluoroquinolone antibacterial agents. The application of the prepared nanocomposite was exemplified in microextraction of the studied fluoroquinolones from spiked milk samples to enable their detection down to their stated maximum residue limits., (Copyright © 2022. Published by Elsevier B.V.)

Allergic rhinitis and urticaria are extremely prevalent among all age groups. From the clinical experience, usually, an essential second-generation non-sedating H 1 -antihistaminic drug, such as bilastine is given to relieve allergic symptoms. Bilastine is preferred to be used instead of oral corticosteroids and first -generation sedating H 1 -antihistaminics to avoid their side effects. A highly sensitive and simple spectrofluorometric method was developed and validated for the determination of bilastine in its dosage forms and biological fluids. The quantum yield was calculated and was found to be as high as 0.48. Aqueous water solution of bilastine gives high native fluorescence emission at 298 nm after excitation at 272 nm. A rectilinear calibration plot was obtained over the concentration range of 1.0-50.0 ng mL -1 . The limits of quantitation and detection were 1.0 and 0.33 ng mL -1 , respectively. The parameters influencing its spectrofluorimetric behavior, viz, type of solvent, pH and organized media were studied. The proposed method was successfully applied for the determination of the drug in pharmaceutical dosage form and the results obtained were in good agreement with those of given by reported method. The high sensitivity of the proposed method enabled the estimation of the drug in biological matrices, including human plasma and urine samples after simple protein precipitation, and the results obtained were satisfactory., 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.)

Medicinal plants are widely used in folk medicine to treat various diseases. Thonningia sanguinea Vahl is widespread in African traditional medicine, and exhibits antioxidant, antibacterial, antiviral, and anticancer activities. T. sanguinea is a source of phytomedicinal agents that have previously been isolated and structurally elucidated. Herein, gas chromatography combined with tandem mass spectrometry (GC-MS/MS) was used to quantify epipinoresinol, β -sitosterol, eriodictyol, betulinic acid, and secoisolariciresinol contents in the methanolic crude extract and its ethyl acetate fraction for the first time. The ethyl acetate fraction was rich in epipinoresinol, eriodictyol, and secoisolariciresinol at concentrations of 2.3, 3.9, and 2.4 mg/g of dry extract, respectively. The binding interactions of these compounds with the epidermal growth factor receptor (EGFR) were computed using a molecular docking study. The results revealed that the highest binding affinities for the EGFR signaling pathway were attributed to eriodictyol and secoisolariciresinol, with good binding energies of -19.93 and -16.63 Kcal/mol, respectively. These compounds formed good interactions with the key amino acid Met 769 as the co-crystallized ligand. So, the ethyl acetate fraction of T. sanguinea is a promising adjuvant therapy in cancer treatments.

Nine simple, cost-effective, and sensitive spectrophotometric methods were developed to simultaneously assay benoxinate HCl and fluorescein sodium in their co-formulated eye drops without barring common excipients. A direct UV spectrophotometric method (method I) was developed for their FLU assay at 481 nm over the concentration range of 0.6-10.0 μg mL -1 . Meanwhile, BEN was assayed over the concentration range of 1.0-25.0 μg mL -1 by different UV based methods, namely, conventional dual-wavelength method (DW) (method II), first derivative 1 D spectrophotometry (method III), second derivative 2 D spectrophotometry (method IV), ratio spectra difference spectrophotometry (method V), the first derivative of ratio spectra (method VI), ratio subtraction method (method VII), isosbestic point method (ISP) (method VIII) and absorption factor method (method IX). The performance of the proposed methods was assessed relying on the correlation coefficients, relative standard deviations, and limits of detection and quantitation. The variance ratio F-test and Student t-test showed no significant differences between the obtained results of the developed methods and those of reference methods. The proposed methods were also applied to determine studied drugs in commercial eye drops and aqueous humor., 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 © 2021 Elsevier B.V. All rights reserved.)

The novelty of this work is the simultaneous analysis of sulbactam (SUL), ampicillin (AMP), and paracetamol (PARA) in human urine samples, using the environmentally benign RP-HPLC method. A C18 column was used in chromatographic separation using potassium dihydrogen phosphate (10 mmol L -1 , pH 5)/ethanol (90 %, V / V ) as the mobile phase; flow rate was 1.00 mL min -1 . UV detection at 220 nm was used for quantification. The proposed method showed good linearity in the concentration ranges of 2.20-250.00 μg mL -1 for SUL, 2.50-250.00 μg mL -1 for PARA, and 14.50-250.00 μg mL -1 for AMP. Direct injection of urine samples with no prior extraction was performed. This method was found successful in moving towards greener studies of drugs' urinary excretion, by decreasing hazardous solvent consumption and waste. Moreover, the method was applied to investigate the urinary excretion of the drugs and possible interaction between ampicillin and paracetamol., (© 2022 Basma M. Selim., published by Sciendo.)

The current study was designed to investigate the antioxidant and cytotoxic activities of Thonningia sanguinea whole-plant extract. The total phenolic content was determined using Folin-Ciocalteu reagent and found to be 980.1 mg/g, calculated as gallic acid equivalents. The antioxidant capacity was estimated for the crude extract and the phenolic portion of T. sanguinea , whereupon both revealed a dose-dependent scavenging rate of DPPH • with EC 50 values of 36.33 and 11.14 µg/mL, respectively. Chemical profiling of the plant extract was achieved by LC-ESI-TOF-MS/MS analysis, where 17 compounds were assigned, including ten compounds detected in the negative mode and seven detected in the positive mode. The phenolic portion exhibited promising cytotoxic activity against MCF-7 and HepG2 cells, with IC 50 values of 16.67 and 13.51 μg/mL, respectively. Phenolic extract treatment caused apoptosis in MCF-7 cells, with total apoptotic cell death 18.45-fold higher compared to untreated controls, arresting the cell cycle at G2/M by increasing the G2 population by 39.7%, compared to 19.35% for the control. The apoptotic investigation was further validated by the upregulation of proapoptotic genes of P53, Bax, and caspases-3,8 9, and the downregulation of Bcl-2 as the anti-apoptotic gene. Bcl-2 inhibition was also virtualized by good binding interactions through a molecular docking study. Taken together, phenolic extract exhibited promising cytotoxic activity in MCF-7 cells through apoptosis induction and antioxidant activation, so further fractionation studies are recommended for the phenolic extract for specifying the most active compound to be developed as a novel anti-cancer agent.

In recent times, the counterfeiting of pharmaceuticals has been considered a serious trouble especially in developing countries that acquire poor inspection programs. Sildenafil, vardenafil and tadalafil (phosphodiesterase type 5 inhibitors) products have gained wide popularity in treating sexual disorders, for which they are subjected to counterfeiting. For this purpose, a simple, rapid, and novel HPLC method with ultraviolet detection has been simply developed for the simultaneous determination of vardenafil, sildenafil, and tadalafil, and their counterfeits (dapoxetine, paroxetine, citalopram, tramadol and yohimbine) in pharmaceutical dosage forms and counterfeit products such as instant coffee and honey. The separation was carried out on a C 18 column, with acetonitrile and an aqueous 0.05% formic acid solution as the mobile phase with a gradient program and at a flow rate of 1 mL min -1 . UV detection was accurately set at 230 nm. The total run time was 11 min for elution of these eight drugs. A UPLC-MS/MS method was also developed, by which compounds were separated in only 6 min, and it was used as a confirmatory tool for studied compounds by identification of their mass spectra. Proposed methods were validated by following ICH guidelines. Both methods were found to be linear, specific, precise and accurate, and they were efficiently applied to analyze 50 commercial products including honey sachets, instant coffee and pharmaceutical products marketed as aphrodisiacs and suspected to contain PDE5-inhibitors., Competing Interests: The authors have declared no conflict of interest., (This journal is © The Royal Society of Chemistry.)

The aim of this study was to investigate the stability of three major antioxidants of Nigella sativa: thymoquinone (TQ), carvacrol (CR) and thymol (THY), under different stress conditions using HPLC and LC-MS/MS. Forced degradation for each compound was performed under different conditions, including oxidation, hydrolysis, photolysis and thermal decomposition. The results showed that both CR and THY were stable under the studied conditions, whereas TQ was not affected by acidic, basic and oxidative forced conditions but the effect of light and heat was significant. The degradation products of TQ were further investigated and characterized by LC-MS/MS. HPLC-UV method has been fully validated in terms of linearity and range, the limit of detection and quantitation, precision, selectivity, accuracy and robustness. The method was successfully applied to quantitative analysis of the principal antioxidants of Nigella sativa TQ, CR and THY in different phytopharmaceuticals.

Cost-effective, green, simple and reliable transmission Fourier-transform infrared (FTIR) spectroscopic method was developed for simultaneous analysis of hypoglycemic drugs in their binary mixtures for the first time. The FTIR method was applied for the determination of vildagliptin (VILD), glimepiride (GLIM) and pioglitazone (PIOG) in binary mixture with metformin (METF). The method was validated according to the International Conference on Harmonization (ICH) guidelines. The obtained results (expressed in peak areas) are linear with concentration in the range of 0.61-20, 0.26-24 and 0.37-4 μg/mg for VILD, PIOG and GLIM, respectively while the linearity ranges for METF were 0.40-200, 0.26-800 and 0.19-1000 μg/mg with VILD, PIOG and GLIM, respectively. The limits of detection (LODs) were 0.20, 0.08 and 0.12 μg/mg for VILD, PIOG and GLIM, respectively while METF LODs were 0.13, 0.08 and 0.06 μg/mg with VILD, PIOG and GLIM, respectively. The FTIR method has been successfully applied for the determination of the cited binary mixtures in its pharmaceutical tablets and the obtained results showed satisfactory % recovery., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Terpenes are the major components of the essential oils present in various Cannabis sativa L. varieties. These compounds are responsible for the distinctive aromas and flavors. Besides the quantification of the cannabinoids, determination of the terpenes in C. sativa strains could be of importance for the plant selection process. At the University of Mississippi, a GC-MS method has been developed and validated for the quantification of terpenes in cannabis plant material, viz., α -pinene, β -pinene, β- myrcene, limonene, terpinolene, linalool, α -terpineol, β -caryophyllene, α -humulene, and caryophyllene oxide. The method was optimized and fully validated according to AOAC (Association of Official Analytical Chemists) guidelines against reference standards of selected terpenes. Samples were prepared by extraction of the plant material with ethyl acetate containing n -tridecane solution (100 µg/mL) as the internal standard. The concentration-response relationship for all analyzed terpenes using the developed method was linear with r2 values > 0.99. The average recoveries for all terpenes in spiked indoor cultivated samples were between 95.0 - 105.7%, with the exception of terpinolene (67 - 70%). The measured repeatability and intermediate precisions (% relative standard deviation) in all varieties ranged from 0.32 to 8.47%. The limit of detection and limit of quantitation for all targeted terpenes were determined to be 0.25 and 0.75 µg/mL, respectively. The proposed method is highly selective, reliable, and accurate and has been applied to the simultaneous determination of these major terpenes in the C. sativa biomass produced by our facility at the University of Mississippi as well as in confiscated marijuana samples., Competing Interests: The authors declare no conflict of interest., (Georg Thieme Verlag KG Stuttgart · New York.)

Sulfonamides and trimethoprim combinations have been used extensively as antimicrobial agents for prevention and treatment of human and animal infections. Although many microextraction methods were developed for monitoring their residues in environmental water, none of these methods applied liquid-liquid microextraction for this purpose. This work presents for the first time a simultaneous Salt Assisted Liquid-Liquid Microextraction SALLME coupled with HPLC-UV for determination of trimethoprim and six common sulfonamide residues (sulfathiazole, sulfadiazine, sulfadmidine, sulfamethoxazole sulfadoxine and sulfaquinoxaline) in water samples. Co-extraction of trimethoprim with sulfonamides was achieved by the addition of perchloric acid as a chaotropic agent to the extraction medium. Quality by Design framework was applied to develop and optimize both of SALLME and HPLC steps to ensure procedure robustness and sensitivity. Tolerance interval modeling of SALLME responses was applied to construct the design space of SALLME procedure. The optimized HPLC system enabled fast, sensitive and robust separation the extracted compounds within four minutes. The method detection limits of the method were in the range of 2.15-7.64 ng.mL -1 . These values were far below the guidelines recommended limits (35 and 70 ng.mL -1 for each individual sulfonamide and trimethoprim respectively)., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Cannabis ( Cannabis sativa L.) is an annual herbaceous plant that belongs to the family Cannabaceae. Trans -Δ 9 -tetrahydrocannabinol (Δ 9 -THC) and cannabidiol (CBD) are the two major phytocannabinoids accounting for over 40% of the cannabis plant extracts, depending on the variety. At the University of Mississippi, different strains of C. sativa, with different concentration ratios of CBD and Δ 9 -THC, have been tissue cultured via micropropagation and cultivated. A GC-FID method has been developed and validated for the qualitative and quantitative analysis of acid and neutral cannabinoids in C. sativa extracts. The method involves trimethyl silyl derivatization of the extracts. These cannabinoids include tetrahydrocannabivarian, CBD, cannabichromene, trans -Δ 8 -tetrahydrocannabinol, Δ 9 -THC, cannabigerol, cannabinol, cannabidiolic acid, cannabigerolic acid, and Δ 9 -tetrahydrocannabinolic acid-A. The concentration-response relationship of the method indicated a linear relationship between the concentration and peak area ratio with R 2  > 0.999 for all 10 cannabinoids. The precision and accuracy of the method were found to be ≤ 15% and ± 5%, respectively. The limit of detection range was 0.11 - 0.19 µg/mL, and the limit of quantitation was 0.34 - 0.56 µg/mL for all 10 cannabinoids. The developed method is simple, sensitive, reproducible, and suitable for the detection and quantitation of acidic and neutral cannabinoids in different extracts of cannabis varieties. The method was applied to the analysis of these cannabinoids in different parts of the micropropagated cannabis plants (buds, leaves, roots, and stems)., Competing Interests: The authors declare no conflict of interest., (Georg Thieme Verlag KG Stuttgart · New York.)

Four accurate, sensitive and reliable stability indicating chemometric methods were developed for the quantitative determination of Agomelatine (AGM) whether in pure form or in pharmaceutical formulations. Two supervised learning machines' methods; linear artificial neural networks (PC-linANN) preceded by principle component analysis and linear support vector regression (linSVR), were compared with two principle component based methods; principle component regression (PCR) as well as partial least squares (PLS) for the spectrofluorimetric determination of AGM and its degradants. The results showed the benefits behind using linear learning machines' methods and the inherent merits of their algorithms in handling overlapped noisy spectral data especially during the challenging determination of AGM alkaline and acidic degradants (DG1 and DG2). Relative mean squared error of prediction (RMSEP) for the proposed models in the determination of AGM were 1.68, 1.72, 0.68 and 0.22 for PCR, PLS, SVR and PC-linANN; respectively. The results showed the superiority of supervised learning machines' methods over principle component based methods. Besides, the results suggested that linANN is the method of choice for determination of components in low amounts with similar overlapped spectra and narrow linearity range. Comparison between the proposed chemometric models and a reported HPLC method revealed the comparable performance and quantification power of the proposed models.

A new simple, sensitive, rapid and accurate gradient reversed-phase high-performance liquid chromatography with photodiode array detector (RP-HPLC-DAD) was developed and validated for simultaneous analysis of Metronidazole (MNZ), Spiramycin (SPY), Diloxanidefuroate (DIX) and Cliquinol (CLQ) using statistical experimental design. Initially, a resolution V fractional factorial design was used in order to screen five independent factors: the column temperature (°C), pH, phosphate buffer concentration (mM), flow rate (ml/min) and the initial fraction of mobile phase B (%). pH, flow rate and initial fraction of mobile phase B were identified as significant, using analysis of variance. The optimum conditions of separation determined with the aid of central composite design were: (1) initial mobile phase concentration: phosphate buffer/methanol (50/50, v/v), (2) phosphate buffer concentration (50 mM), (3) pH (4.72), (4) column temperature 30°C and (5) mobile phase flow rate (0.8 ml min -1 ). Excellent linearity was observed for all of the standard calibration curves, and the correlation coefficients were above 0.9999. Limits of detection for all of the analyzed compounds ranged between 0.02 and 0.11 μg ml -1 ; limits of quantitation ranged between 0.06 and 0.33 μg ml -1 The proposed method showed good prediction ability. The optimized method was validated according to ICH guidelines. Three commercially available tablets were analyzed showing good % recovery and %RSD., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The resolution of flubendazole (FLB) and its degradants has been accomplished by using liquid chromatography (LC) using an octadecylsilane column and a mobile phase that consists of methanol and (0.1%) formic acid (75:25, v/v). Identification of FLB degradants was achieved with positive electron spray spectrometry detection. Furthermore, high-performance thin layer chromatography (HPTLC) separation was carried out using ethyl acetate:formic acid:acetic acid:water (9.5:0.11:0.11:0.28, v/v/v/v) as a mobile phase. Quantitation was achieved using densitometry at 254 nm. FLB was subjected to conditions of hydrolysis, photolysis, oxidation and thermal degradation. The proposed LC method determined that the kinetics of acidic and basic degradation followed a first-order kinetics, with an activation energy of 17.80 and 13.93 kcal mol(-1) for acidic and alkaline degradation processes, respectively. The pH-rate profiles of degradation of FLB in Britton-Robinson buffer solutions within the pH range (2-12) were studied. The developed methods were validated within the corresponding linear ranges of 3-30 µg mL(-1) with detection limits of 0.11 and 0.13 µg mL(-1) for FLB and DG1, respectively, for the high-performance liquid chromatography method and 10-65 and 5-30 µg band(-1) with detection limits of 0.22 and 0.30 µg band(-1) for FLB and DG1, respectively, for the HPTLC method., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Chemometric-assisted spectrophotometric methods and high performance liquid chromatography (HPLC) were developed for the simultaneous determination of the seven most commonly prescribed β-blockers (atenolol, sotalol, metoprolol, bisoprolol, propranolol, carvedilol and nebivolol). Principal component regression PCR, partial least square PLS and PLS with previous wavelength selection by genetic algorithm (GA-PLS) were used for chemometric analysis of spectral data of these drugs. The compositions of the mixtures used in the calibration set were varied to cover the linearity ranges 0.7-10 μg ml(-1) for AT, 1-15 μg ml(-1) for ST, 1-15 μg ml(-1) for MT, 0.3-5 μg ml(-1) for BS, 0.1-3 μg ml(-1) for PR, 0.1-3 μg ml(-1) for CV and 0.7-5 μg ml(-1) for NB. The analytical performances of these chemometric methods were characterized by relative prediction errors and were compared with each other. GA-PLS showed superiority over the other applied multivariate methods due to the wavelength selection. A new gradient HPLC method had been developed using statistical experimental design. Optimum conditions of separation were determined with the aid of central composite design. The developed HPLC method was found to be linear in the range of 0.2-20 μg ml(-1) for AT, 0.2-20 μg ml(-1) for ST, 0.1-15 μg ml(-1) for MT, 0.1-15 μg ml(-1) for BS, 0.1-13 μg ml(-1) for PR, 0.1-13 μg ml(-1) for CV and 0.4-20 μg ml(-1) for NB. No significant difference between the results of the proposed GA-PLS and HPLC methods with respect to accuracy and precision. The proposed analytical methods did not show any interference of the excipients when applied to pharmaceutical products., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In this study, three-dimensional desirability spaces were introduced as a graphical representation method of design space. This was illustrated in the context of application of quality-by-design concepts on development of a stability indicating gradient reversed-phase high-performance liquid chromatography method for the determination of vinpocetine and α-tocopheryl acetate in a capsule dosage form. A mechanistic retention model to optimize gradient time, initial organic solvent concentration and ternary solvent ratio was constructed for each compound from six experimental runs. Then, desirability function of each optimized criterion and subsequently the global desirability function were calculated throughout the knowledge space. The three-dimensional desirability spaces were plotted as zones exceeding a threshold value of desirability index in space defined by the three optimized method parameters. Probabilistic mapping of desirability index aided selection of design space within the potential desirability subspaces. Three-dimensional desirability spaces offered better visualization and potential design spaces for the method as a function of three method parameters with ability to assign priorities to this critical quality as compared with the corresponding resolution spaces., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Tea bags including fruits of Ammi visnaga L. are used in Egypt as remedy for the treatment of kidney stones. Our study focuses on developing simple and rapid method utilising HPLC for quantitative estimation of khellol glucoside (KG), khellin (KH) and visnagin (VS) simultaneously. Their concentrations were determined in A. visnaga L. fruits at different developmental stages and in pharmaceutical formulations together with following up them during shelf life. Separation was accomplished using HPLC. Perfect resolution between KG, KH and VS was possible through using a mobile phase consisting of water:methanol:tetrahydrofuran (50:45:5, v/v/v). Peaks were detected at 245 nm. The suggested method for the determination of KG, KH and VS was successful in determining the analytes of interest without any interference of other compounds and matrix. All validation parameters were satisfactory and the procedure was relatively easy and fast as extracts are evaluated without previous steps of purification.

Metronidazole (MNZ) is a widely used antibacterial and amoebicide drug. Therefore, it is important to develop a rapid and specific analytical method for the determination of MNZ in mixture with Spiramycin (SPY), Diloxanide (DIX) and Cliquinol (CLQ) in pharmaceutical preparations. This work describes simple, sensitive and reliable six multivariate calibration methods, namely linear and nonlinear artificial neural networks preceded by genetic algorithm (GA-ANN) and principle component analysis (PCA-ANN) as well as partial least squares (PLS) either alone or preceded by genetic algorithm (GA-PLS) for UV spectrophotometric determination of MNZ, SPY, DIX and CLQ in pharmaceutical preparations with no interference of pharmaceutical additives. The results manifest the problem of nonlinearity and how models like ANN can handle it. Analytical performance of these methods was statistically validated with respect to linearity, accuracy, precision and specificity. The developed methods indicate the ability of the previously mentioned multivariate calibration models to handle and solve UV spectra of the four components' mixtures using easy and widely used UV spectrophotometer., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A high-performance liquid chromatography method employing diode array detection was developed to determine levels of the major catechins, proanthocyanidin (procyanidin B2), caffeine, thymoquinone and carvacrol and its isomer, thymol, which are present in different natural complex matrices found in commercial products of Camellia sinensis L. and/or Nigella sativa L. Reversed-phase separation was performed on a C18 column by using gradient elution by varying the proportions of solvent A (distilled water containing 0.05% orthophosphoric acid) and solvent B (acetonitrile), with a flow rate of 1.5 mL/min and duration of 31 min. Excellent linearity was observed for all standard calibration curves, and correlation coefficients were above 0.9996. The developed method is efficient, with high reproducibility and sensitivity, and is ideally suited for rapid and routine analysis of principal components in these promising medicinal plants., (© The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

An LC method was developed for the quantitative determination of pipoxolan hydrochloride (PPH) and its degradant. Forced degradation studies were performed on bulk sample using acid (1 M hydrochloric acid), alkaline (0.2 M sodium hydroxide), oxidation (0.33% hydrogen peroxide), heat (70 degrees C), and photolytic degradation. The chromatographic method was fine-tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponding to the degradants and the analyte was achieved on a Discovery C18 LC column (25 cm x 4.6 mm id, 5 pm particle size). The mobile phase was methanol-10 mM sodium dihydrogen phosphate (60+40, v/v); pH was adjusted to 6.5 using 0.2 M sodium hydroxide. Quantitation was achieved with UV detection at 214 nm based on peak area. The proposed LC method was used to investigate the kinetics of acidic and alkaline degradation processes of PPH at different temperatures, and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. The pH-rate profiles of degradation of PPH in Britton-Robinson buffer solutions within the pH range 2-12 were studied. The developed method was validated with respect to linearity, accuracy, precision, and robustness. Forced degradation studies proved the stability-indicating power of the method.

The present work describes validated high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) methods for the simultaneous determination of colchicine and khellin. The isocratic reversed-phase HPLC separation was performed on a 5 µm C18 column (Luna, Phenomenex, Torrance, CA). Good resolution between colchicine and khellin was achieved using a mixture of acetonitrile-10 mM NaH(2)PO(4) (pH 3.0, 35:65 v/v) as a mobile phase. Quantitation was achieved with ultraviolet detection at 245 nm based on peak area. The HPTLC separation was conducted on Merck HPTLC aluminum sheets of silica gel 60 F254 as stationary phase using methylene chloride-methanol (95:5 v/v) as a mobile phase. Quantification was also achieved using densitometric measurements at 245 nm. Both methods revealed reasonable validation parameters concerning selectivity, linearity, accuracy, precision and limits of detection and quantitation.

Sulfonamides are one of the most frequently used antibiotics worldwide. Therefore, mitigation processes such as abiotic or biotic degradation are of interest. Photodegradation and biodegradation are the potentially significant removal mechanisms for pharmaceuticals in aquatic environments. The photolysis of sulfamethoxypyridazine (SMP) using a medium pressure Hg-lamp was evaluated in three different media: Millipore water pH 6.1 (MW), effluent from sewage treatment plant pH 7.6 (STP), and buffered demineralized water pH 7.4 (BDW). Identification of transformation products (TPs) was performed by LC-UV-MS/MS. The biodegradation of SMP using two tests from the OECD series was studied: Closed Bottle test (OECD 301 D), and Manometric Respirometry test (OECD 301 F). In biodegradation tests, it was found that SMP was not readily biodegradable so it may pose a risk to the environment. The results showed that SMP was removed completely within 128 min of irradiation in the three media, and the degradation rate was different for each investigated type of water. However, dissolved organic carbon (DOC) was not removed in BDW and only little DOC removal was observed in MW and STP, thus indicating the formation of TPs. Analysis by LC-UV-MS/MS revealed new TPs formed. The hydroxylation of SMP represents the main photodegradation pathway., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A simple and fast reverse-phase high-performance liquid chromatography procedure coupled with photodiode array detector (RP-HPLC-DAD) was developed and validated for the analysis of major catechins, proanthocyanidin (procyanidin B2) and caffeine in 25 different natural complex matrices containing Camellia sinensis L. and/or grape seed extracts, two popular plant extracts that have been widely used as natural antioxidants in various food and beverage applications. Using an isocratic elution system, separation of all compounds was achieved within 12 min. Excellent linearity was observed for all of the standard calibration curves, and the correlation coefficients were above 0.9997. Limits of detection for all of the analyzed compounds ranged between 2.80×10(-3) and 2.51×10(-2) μg mL(-1); limits of quantitation ranged between 9.30×10(-3) and 8.36×10(-2) μg mL(-1). The developed method was found to be accurate and sensitive and is ideally suited for rapid, routine analysis of principal components in these well-known natural antioxidants., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A new, simple, sensitive, rapid, and accurate isocratic RP-HPLC method was developed and validated for simultaneous analysis of the principal antioxidants of Nigella sativa, i.e., thymoquinone (TQ), carvacrol (CR), and its isomer thymol (THY), in different phytopharmaceuticals. The mobile phase was water-methanol (40 + 60, v/v) at a flow rate of 1.5 mL/min. Quantification was achieved with UV detection at 254 nm, based on peak area. The method was validated for linearity, accuracy, precision, selectivity, and robustness. The proposed method is stability-indicating for determination of TQ in the presence of its degradants. The LOD and LOQ (microg/mL) were, respectively, 0.006 and 0.021 for TQ, 0.002 and 0.006 for CR, and 0.027 and 0.090 for THY. The mean recoveries measured at three concentrations were higher than 99%, with RSD <2%. This analytical method is suitable for quality control of the marker substances in this widely used natural protective and curative remedy.

A high-performance liquid chromatographic method was optimized and validated for the determination of desacetyl nitazoxanide (tizoxanide), the main active metabolite of nitazoxanide in human plasma, urine and breast milk. The proposed method used a CN column with mobile phase consisting of acetonitrile-12mM ammonium acetate-diethylamine in the ratio of 30:70:0.1 (v/v/v) and buffered at pH 4.0 with acetic acid, with a flow rate of 1.5 mL/min. Quantitation was achieved with UV detection at 260 nm using nifuroxazide as internal standard. A simplified direct injection of urine samples without extraction in addition to the urinary excretion pattern were calculated using the proposed method. Also, the effectiveness of protein precipitation and a clean-up procedure were investigated for biological plasma and human breast milk samples. The validation study of the proposed method was successfully carried out in an assay range between 0.2 and 20 µg/mL.

Chemometrics is the application of statistical and mathematical methods to analytical data to permit maximum collection and extraction of useful information. The utility of chemometric techniques as tools enabling multidimensional calibration of selected spectroscopic, electrochemical, and chromatographic methods is demonstrated. Application of this approach mainly for interpretation of UV-Vis and near-IR (NIR) spectra, as well as for data obtained by other instrumental methods, makes identification and quantitative analysis of active substances in complex mixtures possible, especially in the analysis of pharmaceutical preparations present in the market. Such analytical work is carried out by the use of advanced chemical instruments and data processing, which has led to a need for advanced methods to design experiments, calibrate instruments, and analyze the resulting data. The purpose of this review is to describe various chemometric methods in combination with UV-Vis spectrophotometry, NIR spectroscopy, fluorescence spectroscopy, electroanalysis, chromatographic separation, and flow-injection analysis for the analysis of drugs in pharmaceutical preparations. Theoretical and practical aspects are described with pharmaceutical examples of chemometric applications. This review will concentrate on gaining an understanding of how chemometrics can be useful in the modern analytical laboratory. A selection of the most challenging problems faced in pharmaceutical analysis is presented, the potential for chemometrics is considered, and some consequent implications for utilization are discussed. The reader can refer to the citations wherever appropriate.

A simple and reliable precolumn derivatization liquid chromatography method with ultraviolet detection has been developed and validated for the analysis of glucosamine (GS) in various dietary supplement formulations and raw materials. Additionally, the proposed method was used for analysis of carisoprodol (CR) found in ternary mixture with paracetamol (PR) and caffeine (CF). The linearity ranges were 1-100 μg/mL for GS, 1-150 μg/mL for CR, PR and CF. Derivatization was used with 1,2-naphthoquinone-4-sulphonic acid sodium salt in the presence of borate buffer. Chromatographic separation of GS-naphthoquinone derivative was achieved by using a mixture of acetonitrile and water (pH 7.3 adjusted with 0.1 M NaOH) in the ratio 10:90, v/v and flow-rate of 1.0 mL/min. UV detection was carried out at 280 nm. For PR, CF, and CR-naphthoquinone derivative, the chromatographic separation was achieved by using mixture of acetonitrile and 20 mM KH(2)PO(4) (pH 3.0 adjusted with phosphoric acid) in the ratio 20:80, v/v and flow-rate of 1.0 mL/min. UV detection was carried out at 275 nm. The limits of detection were 37.2, 35.9, 30.4 and 40.0 ng/mL for GS, CR, PR and CF, respectively., (© The Author [2012]. Published by Oxford University Press. All rights reserved.)

Application of a sensitive and rapid flow injection analysis (FIA) method for determination of topiramate, piracetam, and levetiracetam in pharmaceutical formulations has been investigated. The method is based on the reaction with ortho-phtalaldehyde and 2-mercaptoethanol in a basic buffer and measurement of absorbance at 295 nm under flow conditions. Variables affecting the determination such as sample injection volume, pH, ionic strength, reagent concentrations, flow rate of reagent and other FIA parameters were optimized to produce the most sensitive and reproducible results using a quarter-fraction factorial design, for five factors at two levels. Also, the method has been optimized and fully validated in terms of linearity and range, limit of detection and quantitation, precision, selectivity and accuracy. The method was successfully applied to the analysis of pharmaceutical preparations.

A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed which can separate and accurately quantitate paracetamol, dantrolene, cetirizine and pseudoephedrine. The method was successfully validated for the purpose of conducting stability studies of the four analytes in quality control (QC) laboratories. The stability-indicating capability of the method was demonstrated by adequate separation of these four analytes from all the degradant peaks. A gradient mobile phase system consisting of (A) 50 mmol L(-1) sodium dihydrogen phosphate, 5 mmol L(-1) heptane sulfonic acid sodium salt, pH 4.2 and (B) acetonitrile was used with Discovery reversed-phase HS C(18) analytical column (250 mm x 4.6 mm i.d., 5 microm particle size). Quantitation was achieved with UV detection at 214 nm, based on peak area. The proposed method was validated and successfully applied for the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the two multicomponent combinations.

High-performance liquid chromatographic method was developed for the quantitative determination of dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB) and its degradation products. Forced degradation studies were performed on bulk sample of DDB using acid (1N hydrochloric acid), alkaline (0.1N sodium hydroxide), oxidation (0.33% hydrogen peroxide), heat (70 degrees C) and photolytic degradation. The chromatographic method was fine tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponds to degradation products and the analyte was achieved on 5 microm ODS column (Luna, Phenomenex, USA). The mobile phase consists of a mixture of acetonitrile and water (60:40, v/v). Quantitation was achieved with UV detection at 235 nm based on peak area. The proposed HPLC method was utilized to investigate the kinetics of acidic, alkaline and oxidative degradation processes of DDB at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The pH-rate profiles of degradation of DDB in Britton-Robinson buffer solutions within the pH range 2-11 were studied. The developed method was validated with respect to linearity, accuracy, precision, robustness and forced degradation studies prove the stability-indicating power of the method.

High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C(18) analytical column with a mobile phase consisting of a mixture of 20mM potassium dihydrogen phosphate, pH 6-acetonitrile in ratio of (1:1, v/v) and UV detection at 245 nm. Also, the resolution has been accomplished by using numerical spectrophotometric methods as classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-1) applied to the UV spectra of the mixture and graphical spectrophotometric method as first derivative of the ratio spectra ((1)DD) method. Analytical figures of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of quantitation and limit of detection were determined for CLS, PLS-1 and PCR methods. The proposed methods were validated and successfully applied for the analysis of pharmaceutical formulation and laboratory-prepared mixtures containing the two component combination.