Acetate Buffer pH Research Articles

Mechanistic characterization of iron-catalyzed oxidation of polysorbate 80: the role of ferrous iron, hydrogen peroxide, and superoxide

We investigated the role of individual radical species during Fe-catalyzed oxidation of PS80. Solutions containing 1 gL-1 PS80 (0.1% w/v) in 10 mM acetate buffer (pH 6) were exposed to various amounts of either Fe(II) or Fe(III), hydrogen peroxide (H2O2), and various enzymes or antioxidants. PS80 oxidation was measured using a fluorescence micelle assay (FMA) alongside LC-MS. Hydrogen peroxide inhibited PS80 oxidation in the presence of Fe(II) but promoted oxidation in the presence of Fe(III). Furthermore, Ferrostatin-1 (Fer-1), an antioxidant which is known to preferentially react with alkoxy radicals, inhibited PS80 oxidation in the presence of Fe(II). Superoxide dismutase (SOD) partially inhibited PS80 oxidation in the presence of either Fe(II) or Fe(III), suggesting that superoxide plays a role in both cases. Ferryl species (FeIV=O) or hydroxyl radicals (HO•), produced by the Fenton reaction, do not play a major role in the oxidation of PS80. Rather, oxidation was initiated by the reaction of both Fe(II) and Fe(III) with pre-existing lipid hydroperoxides on PS80, as well as via superoxide.

Early developments toward HbA1c determination in whole blood by high-speed sample preparation and LC-MS/MS analysis.

We report a method to determine HbA1c (glycated hemoglobin) where whole blood samples are prepared by fast hemolysis (dilution with deionized water and vortex mixing), digestion with 0.6mg/mL endoproteinase Glu C (Glu C) in 30mM ammonium acetate buffer (pH 4.3) at 37°C for 45min, and termination of the digestion by diluting with 0.1% formic acid in water, and then analysis by a gradient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with a run time of 36s. The method is linear between 0 and 200 HbA1c/mol Hb (IFCC) with a correlation coefficient of 0.999, providing an inter-day reproducibility between 1.3 and 2.3% CV, and comparable with results from analysis of the same samples on the Roche Cobas® c 513 clinical analyzer with a correlation coefficient of 0.998. In two alternative detection workflows that were not characterized in detail, the same digested samples were purified by a magnetic bead-based solid-phase extraction (SPE) method requiring about 10min and then analyzed using either an isocratic LC-MS/MS method or a flow injection analysis (FIA)-MS/MS method with run times of 12s and 18s, respectively. Our work demonstrates the feasibility of LC-MS-based methods for HbA1c determination that minimize the time required for sample preparation and measurement while preserving analytical performance and are thereby more suitable for routine clinical settings compared to traditional methods which require up to 25h and 23min, respectively, to prepare and measure samples.

Green synthesis of self-oriented flower-like Ag@Ag2O nanostructures functionalized with L-Tryptophan for colorimetric simultaneous determination of ultra-trace level of thiamin and riboflavin

The study focuses on the green synthesis of Ag@Ag2O nanostructures using Padina algae extract and functionalizing them with L-tryptophan to enhance their properties as a colorimetric sensor for simultaneous detection of ultra-trace levels of thiamin and riboflavin. The nanostructures are characterized using techniques like XRD, FESEM, FTIR, TEM, AFM, and DLS to understand their morphology, structure, and interactions with target molecules. FESEM analysis revealed the hierarchical flower-like Ag@Ag2O nanostructures. The TEM image shows the formation of core-shell nanostructures. Also, DLS analysis and surface zeta potential spectra illustrated the aggregated nature of fabricated nanocomposites in the presence of vitamins. The study is the first to report simultaneous determination of thiamin and riboflavin using a colorimetric sensor based on Ag@Ag2O-L-Try nanocomposites using partial leas square (PLS). The dynamic range of thiamin and riboflavin was achieved in 0.1 mol L−1 acetate buffer pH 4 and the ratio Ag@Ag2O: L-try 1:1. The Ag@Ag2O-L-Try sensor exhibited two linear ranges of 0.1- 1.0 and 3-350 µMol L− 1 for riboflavin and a linear range 3.0–60 µMol L− 1 for thiamin. Also, low detection limit of 1.92 µMol L− 1 and 0.048 µMol L− 1 was obtained for riboflavin and thiamin, respectively. The results indicated that the success of the method depends on the selective and sensitive colorimetric assay of the sensor along with the simultaneous determination by the PLS algorithm. Hence, the proposed technique can be used for the accurate and precise determination of vitamins in different pharmaceutical syrup and tablet samples.

Synthesis and Characterization of Acacia-Stabilized Doxorubicin-Loaded Gold Nanoparticles for Breast Cancer Therapy.

The targeted delivery of drugs is vital in breast cancer treatment due to its ability to produce long-lasting therapeutic effects with minimal side effects. This study reports the successful development of doxorubicin hydrochloride (DOX)-loaded colloidal gold nanoparticles stabilized with acacia gum (AG). Optimization studies varied AG concentrations (0.25% to 3% w/v) to determine optimal conditions for nanoparticle synthesis. The resulting acacia stabilized gold nanoparticles (AGNPs) were characterized using various techniques including high-resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), and selected area electron diffraction (SAED). In vitro drug release studies demonstrated a higher release rate of DOX in sodium acetate buffer (pH 5.0) compared to phosphate buffer saline (pH 7.4), suggesting an enhanced therapeutic efficacy in acidic tumor environments. Cytotoxicity of DOX-AGNPs and free DOX was assessed in human breast cancer cells (MDA-MB-231). The DOX-AGNPs exhibited significantly greater cytotoxicity, indicating enhanced efficacy in targeting cancer cells. This enhancement suggests that adsorbing DOX on the surface of gold nanoparticles can improve drug delivery and effectiveness, potentially reducing side effects compared to pure DOX and traditional delivery methods. Stability tests conducted over six months at 25±1°C showed significant changes in particle size and PDI, suggesting limited stability under these conditions. Overall, the acacia-stabilized gold nanoparticles synthesized in this study exhibit promising characteristics for drug delivery applications, particularly in cancer therapy, with effective drug loading, controlled release, and favorable physicochemical properties.

Determination of ursolic acid in ethanolic extract of Rotheca serrata (L.) Steane & Mabb. by HPLC method

Rotheca serrata (L.) Steane & Mabb. a plant having significant medicinal value is used in treating a fever, rheumatism, inflammation, pain, and malarial fever. Ursolic acid has a five-ringed pentacyclic structure belongs to the family of triterpenoids. It has antioxidant, antitumor, and hepato-protective properties. The method in HPLC was developed on a SHIMADZU, Shimpack ODS (25 cm × 4.6 mm, 5 µm) column. The mobile phase consisted of a 70:25:5 (v/v/v) mixture of methanol, acetonitrile, and 0.02 M ammonium acetate buffer (pH 3.5). A flow rate of 1.2 mL/min and λmax of 215 nm. Ursolic acid from the extract and standard was eluted at the same retention time of 4.1 min. 20–120 µg/mL was the linearity range chosen and was found to be linear (R 2=0.996). The value of LOD was 0.85 µg/mL and LOQ was 1.96 µg/mL. The method for analysis of ursolic was found to be accurate with good repeatability.

Enhanced production of bioethanol through supercritical carbon dioxide-mediated pretreatment and saccharification of dewaxed bagasse

The pretreatment and saccharification of dewaxed bagasse (DWB) has been investigated under various reaction conditions ranging 2000 to 3200 psi, at 70 ± 1 °C in supercritical carbon dioxide (SCC). This has been in attempt to transform the DWB into fermentable sugar and bioethanol in high yields. The effect of SCC mediated pretreatment and enzymatic hydrolysis on structural and morphological alterations in DWB has been ascertained through diverse analytical methods. The sugar has been released through cellulase (40 FPU/mL) mediated enzymatic hydrolysis of pretreated DWB in sodium acetate buffer (pH 4.7) within 1 h at SCC 2800 psi, 70 ± 1 °C. The released sugar was subsequently fermented in the presence of yeast (Saccharomyces crevices, 135 CFU) at 28 ± 1 °C over 72 h to afford the bioethanol. The SCC mediated process conducted in acetic acid:water media (1:1) at 2800 psi, 70 ± 1 °C over 6 h has afforded the pretreated DWB with maximum yield towards the production of fermentable sugar and bioethanol. The production of fermentable sugar and bioethanol has been electrochemically estimated through cyclic voltammetry (CV) and square wave voltammetry (SWV) over glassy carbon electrode in KOH (0.1 M). The electrochemical methods were found selective and in close agreement for estimation of the yields (%) of fermentable sugars and bioethanol. The yield (%) of fermentable sugar estimated from CV and SWV were 80.10 ± 5.34 and 79.00 ± 5.09 respectively. Whereas the yield (%) of bioethanol estimated from CV and SWV were 81.30 ± 2.78% and 78.6 ± 1.25% respectively. Present investigation delivers a SCC mediated green and sustainable method of pretreatment of DWB to afford the enhanced saccharification, to produce bioethanol in high yields.

Development of a simple HPLC method for the determination of urinary O-aminohippuric acid (OAH) and an establishment of OAH reference interval

Background: O-aminohippuric acid (OAH) is considered a low-abundance urinary fluorescent metabolite with the potential to be an innovative lung cancer biomarker. There is a lack of simple methods for measuring urinary OAH metabolite, and the measurement needs to be normalized by urinary creatinine, which is produced at a constant rate. Thus, the newly developed method must be able to determine urinary creatinine and OAH simultaneously in the same run. Objective: This work aimed to develop and validate a simple high-performance liquid chromatography (HPLC) method for measuring urinary OAH and to establish the reference intervals of OAH in healthy individuals. Materials and methods: We synthesized OAH standard in a simple route and optimized simple HPLC method for simultaneous measurement of creatinine and OAH in a single run. Analysis was performed on a RP-C18 column with a gradient elution system of acetonitrile - ammonium acetate buffer (pH 6.5, 100 mM). After implementing optimal conditions, the procedure was compiled according to the International Council for Harmonisation (ICH) validation parameters. The developed method was used for the establishment of reference intervals of a total of 120 random urine samples of healthy individuals. Results: The linear range of the calibration curve for creatinine and OAH were 1-1000 µg/mL and 0.1-100 µg/mL, respectively. The recoveries ranged for both metabolites were between 91.35 % and 109.12%. The relative standard deviations (RSDs) for the intra-day and inter-day results ranged from 0.11-0.66 % to 0.16-1.73 %, respectively. The limits of detection (LOD) and quantification (LOQ) were 0.258 µg/mL and 0.783 µg/mL for creatinine, while OAH was 0.045 µg/mL and 0.137 µg/mL, respectively. The method was successfully applied to establish reference intervals of OAH in healthy individuals and was defined as 0.420-2.287 mmol/mol creatinine. Conclusion: According to various validated parameters, the proposed method was proven to quantify urinary OAH and creatinine in a single run. It can also be analyzed noninvasively without additional sample processing. Reported herein is the first establishment of OAH reference intervals in healthy individuals, which may benefit the utilization of OAH as a noninvasive biomarker for lung cancer detection in the future.

Development and Validation of an ICH-Compliant Optimized RP-HPLC Method for Quantitative Analysis of Favipiravir

Favipiravir (FAV) has emerged as a promising antiviral agent. It is particularly effective against influenza and other RNA virus infections. The aim and objective of the present study was developing and optimizing chromatographic conditions for faster analysis of FAV and demonstrating its applicability for tablet assay. The chromatographic separation was obtained using mobile phase with 90:10 % v/v ratio of ammonium acetate buffer (pH 4.5) and methanol on a Waters C18 column (250 x 4.6 mm, 5 µ). A flow rate of 1.4 mL/min was optimized. Chromatographic detection was perform at a wavelength of 323 nm. The FAV retention time was 6.46 min, indicating the efficiency and speed of the method. The developed method was rigorously validated according to ICH guidelines. A strong linear correlation (r2 = 0.9995) was established in the 5–60 μg/mL range, indicating adequacy for quantitative analysis. The method demonstrated high accuracy, with FAV recovery ranging from 98.77 % to 100.89 %. The % RSD results of less than 2% for intermediate precision and repeatability showed that the method exhibited high precision. The developed HPLC method reduces the Rt. Notably, this method complies with regulatory standards, establishing it as a valuable tool for quality assurance, pharmacological evaluation, and clinical monitoring of FAV. Thus, this validated RP-HPLC method provides a robust and sensitive method for routine FAV quantification, with high accuracy, precision, and compliance results, supporting its potential use in the clinical pharmaceutical industry.

PVC membrane bulk optode incorporating 4-nitrobenzo-15-crown-5 and sodium tetrakis(1-imidazolyl) borate for the pico-molar determination of silver ion in pharmaceutical formulation

Silver ion (Ag+) is of harmful effects to both environment and human health. Ag+ soluble compounds and salts is used in treating mental illness, epilepsy, nicotine addiction, gastroenteritis, and infectious diseases, including syphilis and gonorrhea, and as anti-infective dermatological agent for controlling nose bleeding. However, high Ag+ doses cause several harmful effects to human health such as irreversible pigmentation of skin and eye, and problems to liver and kidney. A bulk membrane Optode is proposed in this work to measure the Ag+ concentration in the pharmaceutical formulations. The membrane optode is prepared from the ionophore 4-nitobenzo-15-crown-5, the ion-exchanger sodium tetrakis (imidazolyl) borate, the plasticizer o-nitrophenyl octyl ether, and the chromoionophore ETH 5294; these components are dissolved in the PVC/THF slurry to form the membrane. The optode is studied by atomic force microscope and UV–visible spectrophotometer, and its spectrum exhibits two maximum wavelengths of 550 and 665 nm, and response for Ag+ at these maximum wavelengths is reproducible in the concentration range of 10–11 to 10–8 M using acetate buffer of pH 5.0, with very low detection limit of 8.8 × 10–12 M. The most important feature in this work is the selectivity improvement for Ag+ over all interfering ions; the selectivity coefficient logarithm logKAg+,cationopt\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${logK}_{Ag+, cation}^{opt}$$\\end{document} is found to be − 4.3 for Cu2+, − 5.6 for Ni2+ and − 5.0 for Cd2+. The response mechanism is studied by FTIR, and it depends on ion-exchange of Ag+ and sodium imidazolyl borate, followed by the host–guest complexation between Ag+ and the crown ionophore, which is accompanied by concomitant deprotonation of the chromoionphore. The optode has a response time of 2–3 min within lifetime of 10 days with the same response. The optode can be applied successfully for Ag+ determination in the pharmaceutical formulation, PinkEye Relief® eye drop, which is used for treating inflammation, redness and water discharge of the eye; the high recovery and low standard deviation of the results using calibration curve method confirm the accuracy and precision of the proposed optode for its application in real samples.

Determination of Enantiomeric Impurity in Tegoprazan Drug Substance by HPLC

ABSTRACTTegoprazan is a novel potassium‐competitive acid blocker used for gastroesophageal reflux disease. It is administered as the (S)‐ and (R)‐enantiomers are considered impurities that should be controlled. The objective of this work was to establish a chiral analytical method for the determination of the enantiomeric impurity of tegoprazan in the drug substance by high‐performance liquid chromatography (HPLC). Enantioselective separation was performed on a Chiralpak alpha1‐acid glycoprotein (AGP) column (4.6 mm × 250 mm, 5.0 µm) at 30°C utilizing a mobile phase consisting of 5 mmol L−1 ammonium acetate buffer (pH 6.0) and 2‐propanol (93:7, v/v) at a flow rate of 0.7 mL min−1 with a detection wavelength of 220 nm. The effects of chromatographic conditions, including the type and concentration of organic modifiers, buffer pH, buffer concentration, flow rate, and column temperature, were thoroughly investigated. Under the optimized conditions, the resolution between (S)‐ and (R)‐tegoprazan was greater than 3.0. Moreover, the developed method was validated in terms of linearity, limits of detection (LOD) and quantitation (LOQ), accuracy, precision, and stability. Each enantiomer showed a good linear relationship over the concentration range of 1.0–100 µg mL−1, with the correlation coefficient of 0.9999. The LOD and LOQ were 0.1 and 0.3 µg mL−1, respectively. In addition, the recoveries ranged from 94.10% to 99.39% with a relative standard deviation (RSD) of 1.9%. Application of this proposed method to determine the enantiomeric impurity in tegoprazan drug substance proved satisfactory. The quantitative results were about 2.0%, demonstrating that enantiomeric impurity remained in the tegoprazan drug substance and should be controlled in the quality criteria.

Ultra-sensitive detection of cadmium and lead in water using crown ether gel electromembrane extraction coupled with miniaturized electrochemical system

This study presents the development of an electrochemical technique combined with gel electromembrane extraction (G-EME) for the simultaneous detection of cadmium and lead in environmental water samples. Crown ether (18C6) was added to the gel as a complexing agent and cationic carrier. The electrochemical responses were evaluated using differential pulse anodic stripping voltammetry (DPASV) across various pH levels and deposition times. The most sensitive response (acetate buffer pH 4, deposition time 90 s) was selected for the development of the G-EME process. By applying a 30 V electrical potential across the gel membrane containing 1 % (w/v) of 18C6 for 10 min, positively charged Cd2+ and Pb2+ ions migrated from the donor phase (pH 5.0) through the 18C6@gel membrane (pH 5.0) into the acceptor phase (pH 5.0). This resulted in a linear range from 0.3 to 5 µg/L for Cd2+ and 0.5 to 5 µg/L for Pb2+, with detection limits of 0.10 µg/L and 0.19 µg/L, respectively— up to 120 times more sensitive than direct electrochemical measurements. Furthermore, the proposed technique maintained selectivity for cadmium and lead, despite the presence of other potential heavy metal ions in the environment.

Effects of Ethylenediaminetetraacetic Acid and Some Chlorides of Divalent Metals on the Initial Velocity of Crude Peroxidase from Watermelon Rind

Aim: This study investigated the effects of ethylenediaminetetraacetic acid (EDTA) and some chlorides of divalent metals on the initial velocity of crude peroxidase from watermelon rind Study design: In vitro enzyme assay. Place and Duration of Study: Department of Biochemistry, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Edo State, Nigeria between September 2023 to November 2023. Methodology: The kinetics of the oxidation of Guaiacol by the crude peroxidase from the rind of watermelon in the presence of varying concentrations of EDTA and the chloride salts of iron, copper was determined spectrophotometrically by monitoring the oxidation of Guaiacol to produce a brown tetraguaiacol at a wavelength of 470nm. The various salt concentrations were varied between 0.5 mM and 3 mM. Each of the reaction mixtures used in the kinetic study comprised; 2.3 mL of 0.6 M sodium acetate buffer (pH 5.4), 0.2 mL of 0.02 mM Guaiacol, 0.1 mL of crude extract, 0.2 mL of varying concentration chloride salt, 0.2 mL of 2 mM of H2O2 added last to start the reaction. The final concentration of H2O2 in the 3 mL assay was 0.13 mM. The total volume of the reaction mixture was 3 mL. The absorbance was read every 2 seconds for one minute after adding hydrogen peroxide using a stop-clock. The control had no metal ion but replaced with distilled water Results: Results showed that EDTA reduced the activity of the enzyme in a concentration dependent manner. CuCl2 and FeCl2 activated the enzyme and FeCl2 being a better activator within the salt concentration range of 0.5 mM to 3 mM. Conclusion: These findings are of great importance to industries in understanding the mechanism of action of peroxidase from the rind of watermelon, especially as the search for cheap and alternative sources of peroxidases continues.

First voltammetric analysis of two possible anticancer drug candidates using an unmodified glassy carbon electrode

Dimethyl 2-[2-(1-phenyl-4,5-dihydro-1H-imidazol-2-yl)hydrazinylidene]butanedioate (DIHB) and 8-(3-chlorophenyl)-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-dione (HDIT) are promising candidates for anticancer agents, the first analytical procedures of which are presented in this paper. The commercially available unmodified glassy carbon electrode (GCE) was used as a sensor for the individual and simultaneous differential pulse voltammetric (DPV) determination of these possible anticancer drugs. The findings concerning the electrochemical behaviour indicated that DIHB and HDIT display at GCE, as a sensor, the oxidation peaks at 1.18 and 0.98 V, respectively (vs. Ag/AgCl, 3.0 mol L−1 KCl) in the 0.125 mol L−1 acetate buffer of pH = 4.5, which were employed for their quantification. Various experimental parameters were carefully investigated, to achieve high sensitivity in voltammetric measurements. Finally, under the optimised conditions (t of 60 s, ΔEA of 75 mV, ν of 225 mV s−1, and tm of 2 ms), the proposed DPV procedure with the GCE demonstrated broad linear sensing ranges (1–200 nmol L−1—DIHB and 5–200 nmol L−1—HDIT), boasting the detection limits of 0.18 nmol L−1 for DIHB and 1.1 nmol L−1 for HDIT. Moreover, the developed procedure was distinguished by good selectivity, repeatability of DIHB and HDIT signals and sensor reproducibility. The practical application of this method was demonstrated by analysing the urine reference material without any prior treatment. The results showed that this environmentally friendly approach, with a modification-free sensor, is suitable for the sensitive, selective and rapid quantification of DIHB and HDIT.

Freeze-drying cycle optimization of an amorphous solid dispersion of resveratrol

Resveratrol (RES) has demonstrated advantages as anti-cancer, anti-inflammatory, blood sugar-lowering agent and as cardioprotective agent, among others. Despite RES therapeutic advantages its use in pharmaceutical applications is limited by its low oral bioavailability, mainly due to its poor water solubility. Formulation of poorly water-soluble compound as solid dispersion (SD) converts a crystalline into a more soluble in water amorphous drug. Lyophilization or freeze-drying is a process in which water, an organic solvent, or a co-solvent system is frozen, followed by its removal from the sample, initially by sublimation (primary drying) and then by desorption (secondary drying). This study aimed the development and optimization of a bulk freeze-drying cycle by critical process parameters assessment in each phase to prepare a RES third-generation SD, containing Eudragit E PO as hydrophilic polymer at 1:2 ratio, and Gelucire 44/14 as surfactant at 16 % (w/w) to RES, using a tert-butanol (TBA)/Acetate buffer pH 4.5 (75:25) co-solvent system. A RES third-generation SD with good appearance, not cracked, collapsed, or melted was prepared by an optimized and robust bulk lyophilization process. A physicochemical characterization confirmed the conversion of RES to the amorphous state in the SD and formulation stability after 1 month at 40 °C/75 % RH. Increased solubility and higher dissolution rate compared with pure RES were also obtained.

Green and sensitive detection of olopatadine in aqueous humor using a signal-on fluorimetric approach: GREEnness assessment.

Olopatadine (OLP) is widely utilized as an effective antihistaminic drug for alleviating ocular itching associated with allergic conjunctivitis. With its frequent usage in pharmacies, there arises a pressing need for a cost-effective, easily implementable, environmentally sustainable detection method with high sensitivity. This study presents a novel signal-on fluorimetric method for detecting OLP in both its pure form and aqueous humor. The proposed approach depends on enhancing the weak intrinsic fluorescence emission of OLP, achieving a remarkable increase of up to 680% compared to its intrinsic fluorescence. This enhancement is achieved by forming micelles around protonated OLP using an acetate buffer (pH 3.6) and incorporating a solution of sodium dodecyl sulfate (SDS) surfactant. A strong correlation (R = 0.9996) is observed between the concentration of OLP and fluorescence intensities ranging from 1.0 to 100.0 ng mL-1 with a limit of detection of 0.22 ng mL-1. This described method is successfully employed for quantifying OLP in both its powder form and pharmaceutical eye drops. Furthermore, it demonstrates robust performance in determining OLP in artificial aqueous humor with a percentage recovery of 99.05 ± 1.51, with minimal interference from matrix interferents. Moreover, the greenness of the described method was evaluated.

A new process related impurity identification, characterization, development of analytical method by HPLC and method validation for Voriconazole API

AbstractDuring the testing of laboratory Voriconazole API batches, one unidentified impurity (IMP-5.312) was detected employing the Pharmeuropa HPLC technique at a level in excess of 0.10%. This IMP-5.312 was synthesized and then characterized as 6-(3-(2,4-difluorophenyl)-3-hydroxy-4-(1H-1,2,4-triazol-1-yl) butan-2-yl)-5-fluoropyrimidin-4-ol by the corresponding spectral information (MS, 1H-NMR, 13C-NMR, and IR). The IMP-5.312 impurity was effectively quantified using an enhanced HPLC based-technique that was developed as well as validated. The approach made use of a Novapak C18 column with an inner diameter of 3.9 mm and a length of 150 mm (4.0 µm) for chromatographic separation. The analysis of IMP-5.312 was made at 45 °C, with a flow rate (isocratic) of 1.0 mL min−1 and a 256 nm detection wavelength. Acetonitrile, methanol, and 0.1% aqueous trifluoro acetate buffer (pH 4.0) were mixed at a ratio of 15:30:55 (v/v/v) to create the mobile phase for a 20 μL sample injection. The linearity range of 0.25281–1.51690 μg mL−1 had a correlation coefficient more than 0.99942, and the accuracy ranged from 89.3 to 100.3%. It was noted that the established HPLC based-technique was sensitive, specific, and precise. The technique was executed on the current batches of VRC API for IMP-5.312 analysis, and the outcomes were good. For quality control purposes during the manufacturing procedure of VRC, the identification as well as analysis of IMP-5.312 should be helpful. The in silico approach was applied to predict the IMP-5.312 toxicity. The reports indicated that IMP-5.312 in non-mutagenic and categorized as ICH M7 class-5 impurity.

β-galactosidase immobilization on ceramic ultrafiltration membrane for simultaneous lactose hydrolysis and protein separation

Protein and lactose of cheese whey can be separated using ultrafiltration membranes and lactose can be hydrolyzed by β-galactosidase. This study investigated the integration of ultrafiltration and enzymatic hydrolysis for simultaneous protein concentration and lactose hydrolysis. β-galactosidase was immobilized on ceramic membrane via surface activation with gelatin and subsequent enzyme cross-linking with glutaraldehyde. Membrane geometries, buffer types, gelatin and enzyme concentrations were optimized. The optimal results yielded a 63 % enzyme immobilization efficiency and a 93 % lactose hydrolysis rate by using disc membrane, sodium acetate buffer (pH 4.8), sodium phosphate buffer (pH 7.5), 0.1 g/L gelatin concentration, and 5.0 g/L enzyme concentration. The optimized enzymatic membrane was evaluated with synthetic and real whey. In synthetic whey, 85 % lactose hydrolysis and 89 % protein rejection were achieved. While in real whey, 72 % lactose hydrolysis and 83 % protein recovery were obtained. This approach offers a single-step, efficient, and scalable method for whey valorization with potential for industrial applications.

Effect of Temperature on the Removal of Interferences in the Voltammetric Procedure for the Determination of Cr(VI).

The aim of this paper was to investigate the effect of temperature on the removal efficiency of surfactant-induced interferences. Surfactants were removed as a result of mixing with XAD-7 resin. The study was carried out using the example of Cr(VI) determination by adsorption stripping voltammetry (AdSV). Measurements were carried out using a solution containing Cr(VI), acetate buffer (pH = 6.2), DTPA, KNO3, and different surfactants. Ten mL of the solution was mixed with 0.5 g of XAD-7 resin at different temperatures for 5 min prior to voltammetric measurement. The effect of the mixing temperature of the sample with the resin on the voltammetric Cr(VI) signal in the presence of different surfactants was studied in the range from 20 to 60 °C. The proposed method of removing interference from surfactants by mixing the sample with the XAD-7 resin at 60 °C was used for the determination of trace amounts of Cr(VI) in river water containing non-ionic, anionic, cationic surfactants, and biosurfactants.

Antiproliferative activity of syringic acid-loaded nanostructured lipid carriers against MCF-7 human breast carcinoma cells

Syringic acid (SA) is a phenolic herbal compound known to exert antiproliferative properties. However, its poor aqueous solubility and low bioavailability lead to limited therapeutic efficacy in treating breast cancer. Hence, to overcome the above problems, the current study aims to explore the quality by design (QbD) optimized syringic acid loaded nanostructured lipid carriers (SA-NLCs) to treat breast cancer. Here, SA-NLCs were formulated via the hot-melt emulsification method and optimized using the Box-Behnken design. The SA-NLCs exhibited spherical shapes with a particle size and zeta potential of 142.7 ± 4 nm and −14.5 ± 3.6 mV, respectively. The differential scanning calorimetry and powder XRD analyses showed the conversion of crystalline to amorphous form of SA after entrapping into NLCs. Also, the optimized SA-NLCs showed sustained drug release of 75.5 % and 97.6 % in pH 5.5 acetate buffer solution and pH 7.4 phosphate buffer saline respectively. The drug release kinetics study revealed that the optimized SA-NLCs exhibit the Weibull model with the Fickian drug release mechanism. Further, a significantly improved cytotoxicity of the optimized SA-NLCs (IC50: 3.8 ± 0.2 μg/mL) was observed as compared to free SA (IC50: 14.5 ± 1.2 μg/mL) on MCF-7 human breast carcinoma cell lines. Thus, the improved cytotoxicity of SA-NLCs on MCF-7 cell lines can be a suitable strategy for breast cancer treatment.

Electrochemical Detection of Heavy Metal Ions using Gold Nanoparticles on Carbon Dots Extracted from Curry Leaves

Carbon dots (CDs) have attracted attention due to their versatility in electronic and optical properties based on precursor and type of synthesis process. Recently, many researchers have focused on using natural resources or wastes to form CDs. Four samples of CDs have been synthesized from curry leaves using a microwave-assisted approach at heating powers of 700 and 800 V with durations of 5 and 8 minutes. UV-Vis and FTIR spectra reveal the existence of carbon graphitic elements with carboxyl and hydroxyl functional groups on the surfaces of CDs. CVs of AuNPs/CDs/GS electrodes in ferricyanide disclosed that as-synthesized CDs produced using a lower heating power of 700 W exhibit pronounced electrocatalytic activity with sluggish electron transfer kinetics. Conversely, as-synthesized CDs created with a higher heating power of 800 W demonstrate reduced electrocatalytic activity but rapid electron transfer kinetics. Electrochemical detection of Pb2+ ions was observed through a sharp peak around -0.42 to -0.438 V, while detection of Hg2+ ions was observed through two anodic peaks around +0.334 to +0.408 V during a forward scan in acetate buffer (pH 4.5) on AuNPs/CDs/GS electrodes when tested individually. These distinct peaks also appeared in mixture solutions, with a slight reduction in peak current density that suggests the selectivity of the AuNPs/CDs/GS electrodes towards Pb2+ and Hg2+ ion detection. The optimum AuNPs/CDs/GS electrode for sensitive and selective detection of Pb2+ and Hg2+ was recorded using CDs D as a functional supporting matrix for AuNPs that was synthesized using a heating power of 800 W for 8 minutes.