High-performance Liquid Chromatography Grade Research Articles

Donepezil and Quercetin Simultaneous Estimation in Rat Plasma Using Developed Bioanalytical HPLC Method: Relevance in Pharmacokinetic Studies

The objective of this investigation was to create and apply a reliable reverse phase high performance liquid chromatography (RP-HPLC) technique for the concurrent measurement of donepezil (DPZ) and quercetin (QT) in rat blood samples for pharmacokinetic research. This is the first publication that introduces a method for DPZ and QT simultaneous determination in rat plasma by high-performance liquid chromatography (HPLC). Using a mobile phase of methanol and HPLC grade water (pH 2.8; adjusted with 0.05% v/v orthophosphoric acid) 45:55 v/v with 2-3 drops of triethylamine (TEA) in an isocratic elution mode at flow rate of 1.0ml/min, DPZ and QT were successfully separated chromatographically on a Hypersil gold C-18 column (250 mm × 4.6 mm, 5μm). The retention time for DPZ and QT was observed to be 6.3 and 12.3 minutes and was detected at an isobestic wavelength of 273 nm using a UV detector. The method was shown to be precise (%RSD < 2%), accurate (96–100%), and specific for the simultaneous detection of DPZ and QT. Several freeze-thaw cycles of the treated plasma samples did not significantly affect the analyte’s stability. The method’s applicability was subsequently confirmed through an oral pharmacokinetic investigation in rats. Since the results were deemed trustworthy, the validated RP-HPLC method may be used to simultaneously detect and quantify both drugs. The method worked well for evaluating the pharmacokinetic characteristics in wistar rats following a single oral dose of 5 mg/kg of QT and 10 mg/kg of DPZ. It is well acknowledged that the chromatographic process is straightforward, robust, accurate, exact, and repeatable.

Chromatographic method development for simultaneous determination of serotonin, melatonin, and L‐tryptophan: Mass transfer modeling, chromatographic separation factors, and method prediction by artificial neural network

AbstractThis work endeavored to develop a high performance liquid chromatography (HPLC) method for simultaneous quantification of three important biotherapeutic molecules namely, L‐tryptophan, serotonin, and melatonin, present in low amounts in agro‐commodities. In the first approach, using pure chemical standards of the same in a mixture, chromatogram separation parameters such as peak sharpness, peak shouldering, and peak separation were judged by a human panel and biasness‐cum‐decision uncertainties were averted using fuzzy logic analysis. In the second approach, the separation parameters such as peak resolution and separation factors were evaluated to obtain a well‐resolved chromatogram. The parameters of the said separation process were successfully modeled by dimensionless numbers of mass transfer of the analytes in the column; and post‐fitting of mass transfer equations, high R2 was obtained suggesting successful development of the chromatographic process. Euclidean distances between the values of each chromatographic separation parameter and their respective ideal values; the defuzzified scores; findings of mass transfer study; and separation factors concomitantly established that the mobile phase of composition 1% acetic acid in HPLC water (A)–HPLC grade methanol (B) in gradient elution conditions (90% A–10% B) at a flow rate of 1 mL/min could simultaneously quantify the three molecules (μg) in button mushrooms with good resolution. The presence of the said biomolecules in the extract of button mushrooms was also confirmed by electrospray ionization (ESI)‐mass spectrometer (MS). An artificial neural network model (high R2) was also developed for chromatographic users, which would allow accurate prediction of the chromatographic parameters by varying mobile phase composition and flow rates.

Validation of a HPLC method for the determination of diclofenac diethylamine and three of its impurities in a gel pharmaceutic form.

Monitoring impurities in drug products is a principal requirement of pharmaceutical regulatory authorities all over the world to ensure drug safety. For this reason, there is a great need of analytical quality control of dugs products. In this study, a simple, efficient and direct high performance liquid chromatography (HPLC) method was developed for the determination of three impurities of diclofenac. The HPLC method was developed using the mobile phase which consisted of HPLC grade mixture (Acetonitrile and 0.01M phosphoric acid adjusted to pH = 2.3) in the ratio of (25:75 v/v) respectively. The separation was performed in 15 minutes. The calibrations curve of the three impurities were linear; the correlation coefficient was 0.999 at a concentration of (0.00015 - 0.003 µg/mL). The validation of this method shows that this method meets all validation criteria. This shows the reliability of the use of this method for the routine control of diclofenac impurities. The validation of a robust HPLC method for the determination of diclofenac impurities is of great importance for the pharmaceutical industry to control its products.

New method for determination of diclofenac sodium by High Performance Liquid Chromatography

In this study a simple, coast effective and direct simple High Performance Liquid Chromatography (HPLC) method has been developed for the determination of diclofenac sodium in it's pure form and different pharmaceutical preparations. Standard diclofenac sodium and its dosage forms were supplied from Ninava State Company For Drug Industries and Medical Appliances (NDI). HPLC method was developed by using mobile phase which was composed of a mixture of HPLC grade (methanol, acetonitrile and deionized water)in the ratio of (60:20:20) respectively. Separation has been completed within 2 min. Calibration curve was linear, coefficient correlation was found to be 1.00 at a concentration of (0.25-4.0 µg.ml-1). The relative standard deviation (RSD) was found to be >1.2%. The proposed method was successfully applied for the determination of diclofenac sodium in its pure form and different pharmaceutical preparations (injection, tablets, eye drops, suppositories and gel) without using buffer system and there is no inference with additives.

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO 2 Bioreduction

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO ₂ Bioreduction

Study of High Performance Liquid Chromatography Grade Water Quality in Iran

Background: The use of high performance liquid chromatography (HPLC) grade water is very important for laboratory studies, especially food quality control. These studies have a great impact on diagnosing food health. Food health improves the health of the community and these two parameters are closely related. HPLC grade water is ultra-pure water with low UV absorption ability. This water is often purified through a micron filter and all contaminants are removed. Methods: Thirty samples of HPLC grade water with Iranian and non-Iranian brands purchased from Tehran were tested for electrical conductivity and silica. Results: The quality of all the tested samples was approved which was lower than the allowable limit. None of the Iranian and non-Iranian samples exceeded the standard limit. Conclusion: This study indicated the good quality of this product. It was concluded that all the samples had desirable quality.

One-Pot Synthesis of Supertough, Sustainable Polyester Thermoplastic Elastomers Using Block-Like, Gradient Copolymer as Soft Midblock

It remains challenging to synthesize supertough thermoplastic elastomers (TPEs) since the stretchability and tensile strength are mutually exclusive. Here, we report a one-pot strategy for the prep...

Differential adsorption of analyte and deuterated analogue onto the rotor seal of the injector in high-performance liquid chromatography/electrospray ionisation mass spectrometry.

Samples were injected onto the HPLC system via either a Valco C14W.1 internal sample injector or a Rheodyne 7125 injector, both with dissimilar Vespel rotor seals, and linked to a quadrupole time-of-flight (QTOF) mass spectrometer. Alternatively, samples were infused directly into the mass spectrometer via a syringe-driver. Electrospray ionisation in positive mode was used in both cases. Experiments demonstrated significant differential adsorption of the analyte (RAC inhibitor, NSC23766) and its tri-deuterated internal standard onto the Vespel rotor seal, with the latter seeming to be preferentially adsorbed. The deuterated analogue also showed lower electrospray sensitivity, as demonstrated by syringe infusion of a mixture of the compounds, compared with their separate infusion at the same concentration. This study has demonstrated the problem of differential adsorption onto HPLC Vespel rotor seals, and that the use of a stable-isotope-labelled analogue as internal standard does not guarantee the constancy of the analyte/internal response ratio in quantitative methods. The partial solution was to work at much higher concentration where adsorption, whilst still apparent, was relatively insignificant.

Determination of Caffeine in Coffee Samples by High Performance Liquid Chromatography and Ultra Violet - Visible Spectrophotometry Methods from Wollega, Ethiopia

In this research caffeine content in coffee sample from Abe Dongoro, Sasiga, Gida Ayana and Sibu Sire of Wollega administrative zone of Ethiopia were determined using High Performance Liquid Chromatography (HPLC) and UV-Vis Spectrophotometry methods. Caffeine in aqueous extract of coffee samples was extracted with dichloromethane prior to analysis by UV-Vis spectrophotometry method and dichloromethane was evaporated from the extract and the extract was dissolved in water (HPLC grade) to determine caffeine contents in coffee samples using HPLC method. The linearity of the HPLC and UV-Vis spectrophotometry methods were R² = 0.9999 and R² = 0.9997 respectively. HPLC and UV-Vis spectrophotometry methods were found to be accurate with recoveries of 97.5% and 117.4%, respectively. Limits of detection (LOD) obtained were 0.148 mg/L for HPLC method and 0.284 mg/L for UV-Vis spectrophotometric method. The caffeine contents in coffee samples obtained using UV-Vis spectrophotometry method was 3.42, 2.638, 2.207 and 2.986 mg/L for Abe Dongoro, Gida Ayana, Sasiga and Sibu Sire coffee samples respectively. Similarly, using HPLC method the caffeine contents in coffee samples obtained was 1.871, 1.601, 1.307, 1.83 mg/L for Abe Dongoro, Gida Ayana, Sasiga and Sibu Sire coffee samples. There is a significant difference between the caffeine contents in coffee samples obtained by the two methods.

Application of chemometric approach for development and validation of high performance liquid chromatography method for estimation of ropinirole hydrochloride.

A systematic Quality by Design approach was employed for developing an isocratic reversed-phase liquid chromatographic technique for the estimation of ropinirole hydrochloride in bulk drug and pharmaceutical formulations. LiChrospher RP 18-5 Endcapped column (25cm × 4.6mm id) at ambient temperature (25±2°C) was used for the chromatographic separation of the drug. The screening of factors influencing chromatographic separation of the active pharmaceutical ingredient was performed employing fractional factorial design to identify the influential factors. Optimization of the selected factors was carried out using central composite design for selecting the optimum chomatographic conditions. The mobile phase employed was constituted of Solvent A/Solvent B (65:35 v/v) (Solvent A [methanol/0.05M ammonium acetate buffer, pH 7, 80:20 v/v] and Solvent B [high performance liquid chromatography grade water]) and used at 0.6mL/min flow rate, while UV detection was performed at 250nm. Linearity was achieved in the drug concentration range 5-100µg/mL (R2 =0.9998) with limits of detection and quantification of 1.02 and 3.09µg/mL, respectively. Method validation was performed as per ICH guidelines followed by forced degradation studies, which indicated good specificity of the developed method for detecting ropinirole hydrochloride and its possible degradation products in the bulk drug and pharmaceutical formulations.

Development of method of quantitative determination of cardiazol substance with using highly efficient liquid chromatography

The aim. Development of methods of quantitative determination of Cardiazol substance using high-performance liquid chromatography.Materials and methods. The method of high-performance liquid chromato-graphy (HPLC) was to determine of quantitative determination of Cardiazol substance ([3-Allil-4-(41-methoxyphenyl)-3H-thiazole-2-ylidene]-(32-trifluoro-methylphenyl)amine hydrobromide) using Shimadzu Nexera X2 LC -30AD (Shimad-zu, Japan). The acetonitrile of the HPLC grade (Sigma-Aldrich GmbH, Switzerland) was used in the work and other chemicals and solvents were of analytical grade. The test substance was diluted in acetonitrile at a final concentration of 400 μg/ml.Results and discussion. The method of quantitative determination of Cardiazol substance with the help of highly effective liquid chromatography is developed. The developed conditions of testing are selected experimentally. The following optimal conditions for the chromatographic distribution were found: column C8 (250 *4.6 mm; speed of the mobile phase 1 ml/min; thermostat temperature of the column 35 ° C; detecting wavelength 300 nm; holding time of the test compound is 13.9 min. Suitability of determination methods.The following optimal conditions for chromatographic separation were revealed: a C8 column (250*4.6 mm, a mobile phase speed of 1 ml/min, a column thermostat temperature of 35 °C, a detection wavelength of 300 nm. Under the proposed conditions, the retention time of the tested component is 13.9 minutes. The performance of the column was determined for its main indicators, such as the theoretical number of plates (over 65000) and the coefficient of symmetry (about 1.00). The method of quantitative determination was tested in accordance with the recommendations of the Ukrainian and European Pharmacopoeia. The proposed method meets all requirements. The method has been tested for the effects of various factors such as flow rate, the composition of the mobile phase and the temperature of the column thermostat. It is established that the influence of these factors is insignificant and does not affect the results obtained by this method.Conclusions. An analytical method for quantitative determination of Сardiazole substance with cardioprotective action has been developed on the basis of the high-performance liquid chromatography method. The conditions for chromatographic analysis (HPLC) were standardized. Requirements for the test Checking the suitability of the chromatographic system were established. The statistical processing of the results of the experiment shows that the relative uncertainty of the average result was within the permissible limits. The developed method for the determination of Сardiazole will be used for further study of substance as a component of various dosage forms

Pharmacokinetics of citicoline after intravenous and intramuscular administration in dogs

Background: New studies have confirmed the role of citicoline in reversing different pathological conditions in canine medicine, but dosing regimens of this drug has not yet been investigated in dogs. Using a high-performance liquid chromatography (HPLC) system, this study aims to quantify the levels of citicoline in dogs plasma after intravenous (IV) and intramuscular (IM) administration.Design and methods: The subjects of this study were 12 male, mixed breed healthy dogs that were approximately 2 to 3 years old and had a body weight between 15 and 25 kg. Plasma samples were extracted following protein precipitation. Samples were eluted from the column at flow rate of 0.7ml min-1. Solvents were degassed. The PH of the mobile phase of HPLC grade acetonitrile: water (20:80, v/v) was adjusted to 3.0 using 1% orthophosphoric acid. Both sample and standard solutions were filtered through 0.22 µm membrane filter. A sample volume of 20 microliter was injected to HPLC to obtain a standard curve.Results: No clinical signs or drug adverse effect was noticed in animals during and after the period of administration of citicoline. Measuring plasma concentration of citicoline sodium after IV and IM administration showed biphasic plasma peaks which occured at 15 minutes and 5 hours after the drug administration in dogs. Conclusions: Giving the drug once a day with 30-50 mg/kg dosage or twice daily with 15-30 mg/kg dosage would cause their levels to remain elevated for much of the day and doesn’t have any serious adverse effect.

VERSATILE RP-HPLC METHOD DEVELOPMENT FOR QUANTITATIVE ESTIMATION OF TELMISARTAN AND RAMIPRIL IN ANIMAL PLASMA

Objective: A fast, specific, and sensitive high-performance liquid chromatographic method has been developed and validated for the quantitative determination of unchanged Ramipril (RAM) and Telmisartan (TEL) in animal plasma.Methods: Analytes were extracted from animal plasma, 250 µl of animal plasma sample were mixed with internal working standard (25 ngmL-1) with the further addition of chloroform (HPLC Grade, Merck). The clear organic layer was separated and reconstituted to 1 ml in mobile phase and analysed by HPLC. The method was validated and evaluated in terms of linearity, accuracy, precision, specificity, limit of detection and limit of quantitation.Results: Absorption maxima of TEL and RAM was found to be 270 and 273 nm respectively. TEL and RAM with their respective internal standards (I. S.) were found to be well separated from the co-eluted components and there were no interferences from the endogenous material. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 2.01±.05; 4.88±0.10 and 0.11 and 0.25 for TEL and RAM respectively on the basis of a signal to noise ratio. The ruggedness of the method at various parameters was found to be±1.94% and±1.02% for TEL and RAM respectively. The low values of %RSD (<2.0) for each of the drug proposed that during all deliberate variations, middle-quality control (MQC) was not affected and it was in accordance with that of actual.Conclusion: Thus developed High-Performance Liquid Chromatography (HPLC) method was found to be more accurate, precise, sensitive, selective and reproducible.

Method development and validation for dieckol in the standardization of phlorotannin preparations

Phlorotannins are reported to have diverse biological properties. However, no analytical methods for the standardization of phlorotannin preparations have been reported. Herein, we developed and validated an analytical method for the determination of dieckol in phlorotannin extracts (PRT) using high-performance liquid chromatography (HPLC). The optimum HPLC conditions consisted of a Supelco Discovery C18 column stationary phase, a mobile phase (A: 15 % HPLC grade methanol in deionized water, B: methanol), UV detection at 230 nm, and a flow rate of 0.7 mL/min. The optimized chromatographic conditions were validated and exhibited good specificity and linearity (R 2 > 0.9994–1.0000). The recoveries were in the range of 100.9–102.3 %. The method had good intermediate (%RSD 1.2) and intra-day (%RSD 0.4–1.7) assay precisions. This HPLC method had good accuracy and quality in the determination of dieckol in PRT.

A new validated HPLC method for the determination of sulforaphane: application to study pharmacokinetics of sulforaphane in rats

A simple, accurate and reproducible high-performance liquid chromatography (HPLC) method has been developed and validated for the quantification of sulforaphane (SF) in rat plasma. The method involves a simple liquid-liquid extraction procedure to extract both SF and 7-hyrdoxycoumarin, the internal standard. The chromatographic analysis was achieved on a Shimadzu LC 20A HPLC system equipped with a Zorbax Eclipse XDB C18 column and an isocratic mobile phase consisting of 10 mm KH2 PO4 (pH 4.5) and acetonitrile HPLC grade (40:60, v/v) run at a flow rate of 1 mL/min for 10 min. The UV detection wavelength was set at 202 nm. The method exhibited good linearity (R(2) > 0.999) over the assayed concentration range (0.05-2 μg/mL) and demonstrated good intra- and inter-day precision and accuracy (relative standard deviations and the deviation from predicted values were <15%). This method was also successfully applied for studying the pharmacokinetics of SF in spontaneously hypertensive rats following single oral dietary doses of SF. The pharmacokinetics of SF show linear behavior at the dose range investigated in this study. Copyright © 2015 John Wiley & Sons, Ltd.

Overexpression and optimization of glutamate decarboxylase in Lactobacillus plantarum Taj-Apis362 for high gamma-aminobutyric acid production.

Gamma-aminobutyric acid (GABA) is an important bioactive compound biosynthesized by microorganisms through decarboxylation of glutamate by glutamate decarboxylase (GAD). In this study, a full-length GAD gene was obtained by cloning the template deoxyribonucleic acid to pTZ57R/T vector. The open reading frame of the GAD gene showed the cloned gene was composed of 1410 nucleotides and encoded a 469 amino acids protein. To improve the GABA-production, the GAD gene was cloned into pMG36e-LbGAD, and then expressed in Lactobacillus plantarum Taj-Apis362 cells. The overexpression was confirmed by SDS-PAGE and GAD activity, showing a 53 KDa protein with the enzyme activity increased by sevenfold compared with the original GAD activity. The optimal fermentation conditions for GABA production established using response surface methodology were at glutamic acid concentration of 497.973 mM, temperature 36°C, pH 5.31 and time 60 h. Under the conditions, maximum GABA concentration obtained (11.09 mM) was comparable with the predicted value by the model at 11.23 mM. To our knowledge, this is the first report of successful cloning (clone-back) and overexpression of the LbGAD gene from L. plantarum to L. plantarum cells. The recombinant Lactobacillus could be used as a starter culture for direct incorporation into a food system during fermentation for production of GABA-rich products.

Pharmacokinetics of Maraviroc, Raltegravir, Darunavir, and Etravirine in the Semen of HIV-Infected Men

Pharmacokinetics of Maraviroc, Raltegravir, Darunavir, and Etravirine in the Semen of HIV-Infected Men

Properties of a Model Aryl Boronic Acid and Its Boroxine

Many boronic acid-containing molecules are currently under investigation as possible therapeutics. An increase in the knowledge of the physical and chemical properties of these compounds will lead to their improved formulation into usable dosage forms. The current study describes the formation and characterization of a boronic acid anhydride, called a boroxine. The model boronic acid, 4-methoxybenzeneboronic acid is used. The current study demonstrates the utility of thermal (differential scanning calorimetry and thermogravimetric analysis) and spectral (solid-state nuclear magnetic resonance and ultraviolet spectroscopy) methods to quantitate and characterize the boronic acid and its boroxine, validated against definitive structures solved by single-crystal X-ray diffraction. The present work also demonstrates that the hydrolysis of the boroxine in the presence of water is very rapid in a time scale relative to drug substance manufacture and product formulation.

How to write a paper for Rapid Communications in Mass Spectrometry

How to write a paper for <i>Rapid Communications in Mass Spectrometry</i>

Stability of docetaxel infusions

BackgroundAccording to the manufacture, docetaxel infusions should be used within four h at room temperature (<25°C).PurposeTo determine the stability of intravenous mixtures (IVM) at a concentration of 0.7 mg/mL in...