Sensitive High-performance Liquid Chromatography Research Articles

Individualized medication of venetoclax based on therapeutic drug monitoring in Chinese acute myeloid leukemia patients using an HPLC method.

The aim of this study was to establish a simple and sensitive high-performance liquid chromatography method for therapeutic drug monitoring of venetoclax (VEN) and optimize regimens. The analysis required the extraction of a 50 μl plasma sample and the precipitation of proteins using acetonitrile extraction. The chromatographic method employed a mobile phase of acetonitrile: 0.5% KH 2 PO 4 (pH 3.5) (60/40, v/v) on a Diamond C 18 (4.6 mm × 250 mm, 5 μm) column at a flow rate of 1.0 ml/min. The quantitative method was validated based on standards described in 'Bioanalytical Method Validation: Guidance for Industry' published by the US Food and Drug Administration (FDA). The calibration curve was linear ( R2 = 0.9998) over the range of 75-4800 ng/ml, with limits of quantification of 25 ng/ml. The coefficients of intraday and interday validation, specificity, recovery, and stability all met the criteria of FDA guidance. The method was successfully applied to analyze VEN concentrations in 30 cases of acute myeloid leukemia patients. The peak concentration ( Cmax ) was 1881.19 ± 756.61 ng/ml, while the trough concentration ( Cmin ) was 1212.69 ± 767.92 ng/ml in acute myeloid leukemia patients. Our study establishes a simple, precise, and sensitive high-performance liquid chromatography method for monitoring VEN and confirms its applicability for therapeutic drug monitoring of VEN in hematological cancers.

Pharmacokinetics and tissue distribution of LN002, a new compound alternative oxidase inhibitor against Cryptosporidium in rats.

Cryptosporidiosis is considered a crucial zoonotic disease caused by widely distributing parasitic protozoa called Cryptosporidium spp. Nitazoxanide is the only FDA-approved drug but is only effective with a good immune response of the host. In addressing this unmet medical need, we previously identified a compound, namely, LN002, as a potent alternative oxidase inhibitor against cryptosporidiosis. To illustrate the pharmacokinetics, absolute bioavailability, and tissue distribution of LN002 in rats, rapid and sensitive high-performance liquid chromatography was developed and validated for the separation and detection of LN002 in plasma, tissue samples, and intestinal contents. In this study, a single dose of oral administration and intravenous injection of LN002 was used to determine the levels of LN002 in plasma, tissue samples, and intestinal contents by UHLC. Results of the study indicated that after intravenous administration of 1mg/kg LN002, the AUC0-24 h, T1/2,Vd, and Cl were 7024.86h·ng/mL, 10.91h, 1.69L/kg, and 0.11L/h/kg, respectively. After oral administration of a single dosage of 100, 200, and 400mg/kg LN002, the Tmax, Cmax, AUC0-24h, T1/2, F, Vd, and Cl/F in plasma of rats were 1h, 849.88-4033.21ng/mL, 2280.41-7498.10h·ng/mL, 17.96-18.83h, 0.27%-0.32%, 581.54-869.21L/kg, and 25.97-39.00L/h/kg, respectively. After oral administration of 200mg/kg, LN002 was extensively distributed in the main tissues of rats, and massive amounts of LN002 were distributed in the intestine and intestinal contents, indicating its potential as an effective anti-Cryptosporidium compound. After oral administration of a single dosage of 200mg/kg, LN002 has a low bioavailability and high levels in the intestine, which is crucial for the safe and effective treatment of cryptosporidiosis. Overall, the results of this study provide valuable data support for the future study of LN002.

Determination of Veratrum alkaloid contents in three Veratrum species by HPLC-MS/MS.

Veratrum alkaloids have gained attention due to their toxic effects and potential pharmaceutical applications, particularly in cancer and cardiology. Over 200 alkaloids are found in species of the Veratrum genus. The alkaloid composition and concentrations can greatly vary in plants depending on factors like species, plant part, location, season, weather, or nutrients. This study aims an analytical approach to analyze and quantify Veratrum alkaloids in different plant parts of Veratrum species. The purpose is to contribute essential alkaloid concentration data for future research on the pharmacological and toxicological aspects of Veratrum alkaloids. This study focuses on five Veratrum alkaloids (cevadine, jervine, protoveratrine A, veratramine, and veratridine) in three Veratrum species (Veratrum album L., Veratrum californicum Durand, and Veratrum nigrum L.) collected from four German botanical gardens (Dresden, Leipzig, Marburg, and Schellerhau). A liquid-liquid extraction method and a sensitive high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method operating in multiple reaction monitoring (MRM) mode were applied for the alkaloid determination. Quantification revealed varying alkaloid concentrations among plant parts and Veratrum species in the μg/g to mg/g range. Protoveratrine A exhibited the highest content, while veratramine concentrations were generally lower. Especially in fruit, roots and rootstock of Veratrum album L. alkaloid concentrations were significant high. The developed HPLC-MS/MS method successfully determined Veratrum alkaloid concentrations in plant samples. The study contributes valuable data on Veratrum alkaloid distribution in different species and plant parts, crucial for understanding their potential medicinal and toxicological significance.

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR ESTIMATION OF EZETIMIBE IN RABBIT PLASMA USING REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Objectives: The objective of the present work was to develop an analytical method and validation for the estimation of Ezetimibe in rabbit plasma using high-performance liquid chromatography (HPLC). Methods: A simple, rapid, sensitive, and accurate HPLC method was developed and validated for the quantification of Ezetimibe concentration in rabbit plasma using metoclopramide as an internal standard. Separation was performed on the Xerra C18 column (250 × 4.6 mm 5 μm) using a mobile phase consisting of 0.1% perchloric acid: acetonitrile(55:45 v/v) at a flow rate of 1 ml/min. Validation of the method was performed to demonstrate its selectivity, linearity, precision, accuracy, ruggedness, recovery, and matrix effect. Results: The calibration curves of Ezetimibe were linear over a concentration range of 5–1022 μg/mL. The with-in and between-day coefficients of variation were <10%. The extraction recoveries of Ezetimibe at the three levels of quality control samples were 99.961%, 99.767%, and 99.938%. Conclusion: The method was rapid with a retention time of Ezetimibe and the internal standard observed at 10 min, respectively. The developed method was successfully applied to studying the pharmacokinetics of Ezetimibe in rabbits.

Evaluation of aflatoxin content in “Cheka” (traditional beverage in South-Western Ethiopia) and its major ingredient (maize)

BackgroundAflatoxin is a toxic cancerous fungal secondary metabolite produced by Aspergillus species. Consumption of aflatoxin-contaminated cereals and their products can cause several health-related effects including acute and chronic aflatoxicosis. This study aims to evaluate the total aflatoxin content in “Cheka” and its major ingredients using the Immuno-Affinity Column Clean-up technique by sensitive HPLC (High-Performance Liquid Chromatography) with fluorescence detection.MethodsThis study followed a completely randomized experimental design to evaluate the level of aflatoxin in traditionally brewed “Cheka” and its major ingredients (maize) by HPLC from November 2019 to June 2020. Traditionally brewed 6 “Cheka” beverages and 6 maize seed samples were collected randomly from Konso and transported to Bless Agri Food Laboratory in Addis Ababa for laboratory evaluation of aflatoxin in samples. The data were analyzed by SPSS version 25.ResultsIn the present study aflatoxin contamination was detected in all maize and “Cheka” samples. A mean total aflatoxin level of 6.78 ± 8.28 μg/kg and 10.76 ± 4.50 μg/kg were observed in maize and “Cheka” samples respectively. The maize taken from above-ground storage (“Gotera”) and underground storage (pitfall) showed a mean total aflatoxin level of 10.23 ± 10.12 μg/kg and 3.35 ± 5.79 μg/kg respectively. The samples taken from “Cheka” prepared from maize of above-ground storage (“Gotera”) and underground storage (pitfall) showed a mean total aflatoxin level of 11.34 ± 3.06 μg/kg and 10.19 ± 6.35 μg/kg respectively. Aflatoxin G family was not detected in both maize and “Cheka” samples while aflatoxin B1 and B2 contributed to the total aflatoxin level. AFB1 predominantly contributed to the contamination of all samples. Although there was no significant difference while comparing between mean total aflatoxin of any other sample types, a significant difference was observed for the AFB1 mean level of pitfall maize and their respective “Cheka” samples (P = 0.033).ConclusionThe mean level of AFB1 in pitfall maize differs from a respective “Cheka” sample. As most of the samples evaluated for aflatoxin contamination showed levels above healthy cut-off points of aflatoxin set by different authorities like the European Union, CODEX, and Ethiopian Standards Agency, there must be a protracted interventional approach to reduce aflatoxin contamination in maize and its products in the region.

Characterization of Forced Degradation Products of Netarsudil: Optimization and Validation of a Stability-Indicating RP-HPLC Method for Simultaneous Quantification of Process-Related Impurities.

The aim of this study is to examine resolution, identification, and characterization of forced degradation products of netarsudil by liquid chromatography-tandem mass spectrometry by validating a simple and sensitive high-performance liquid chromatography method for the resolution, identification, and quantification of two process-related impurities in netarsudil. Chromatographic separation was accomplished on a ZORBAX Eclipse XDB C18 (250 x 4.6 mm; 5 µ id) column at room temperature as the stationary phase and 257 nm as the detector wavelength with the mobile phase consisting of acetonitrile, methanol, and pH 4.6 phosphate buffer in 45:35:20 (v/v) at 1.0 mL/min flow rate in isocratic elution. The method reported very sensitive detection limits of 0.008 µg/mL for impurity 1 and 0.003 µg/mL for impurity 1. The method produces a calibration curve linear in the concentration level of 25-200 for netarsudil and 0.025-0.2 µg/mL for impurities. The proposed method gives acceptable results for other validation parameters such as accuracy, precision, ruggedness, and robustness. The drug was subjected to various stress conditions such as acid, base, peroxide, and thermal and ultraviolet light to investigate the stability-indicating ability of the method. Considerable degradation was observed in stress studies, and the degradation products were well resolved from process-related impurities. The characterization of degradation products was performed on the basis of collision-induced dissociation mass spectral data, and the possible structures of the six degradation compounds of netarsudil were proposed. The outcomes of other validation studies were likewise satisfactory and proven adequate for the regular analysis of netarsudil and its process-related impurities in bulk drug and pharmaceutical dosage forms and can also be applied for the evaluation of the stress degradation mechanism of netarsudil.

Stability Indicating HPLC Method for In-vitro Determination of Pantoprazole Sodium and its Degradation Products in Simulated Gastric and Intestinal Fluids

Background: A high-performance liquid chromatography (HPLC) method was developed for the determination of Pantoprazole Sodium (PPZ) in the presence of its degradation products. The degradation of PPZ was studied in simulated intestinal fluid (SIF) and simulated gastric fluids (SGF) in various temperature conditions. Aim: This study aimed to establish a simple, sensitive, and rapid RP HPLC method for in-vitro determination of Pantoprazole Sodium and its degradation products in simulated gastric and intestinal fluids. Objective: Pantoprazole is acid labile drug. In order to determine pantoprazole in various oral dosage forms, the stability-indicating assay of PPZ was performed in phosphate buffer (pH 6.8) representing simulated intestinal fluid (SIF) and in 0.1 molars (M) Hydrochloric acid (HCl) as simulated gastric fluid (SGF) at two different temperature conditions, i.e., 25°C and 0°C, respectively. Method: Pantoprazole sodium was obtained from the Akums laboratory in Haridwar. The analysis was performed by high-performance liquid chromatography (HPLC), Shimadzu, equipped with two LC-10 AD VP solvent-delivery modules, a SPD-10A UV–-visible detector, and a manual injector valve with 20 μL sample loop. Phenomenex ODS analytical column (150 mm × 4.6 mm i.d., 5 μm particles) was done under reversed-phase partition chromatographic conditions. The mobile phase was phosphate buffer and acetonitrile (ACN) of pH 7.4, respectively, optimized in a 70:30 (v/v) ratio followed by filtration through a 0.45 μm membrane filter and degassed by ultrasonicator before use. The mobile phase was delivered at the flow rate of 2 mL/min. The various parameters, such as linearity, accuracy and precision of the analytical method, were studied. Result: The standard curve of PPZ was linear (R2>0.99) over the concentration range of 5-30 μg/mL, and the relative standard deviation (RSD) values for intra-day and inter-day variations were in the range of 1.0-1.8%. The range of RSD was within ±2. Conclusion: The stability of PPZ in aqueous solution was pH dependent. The rate of degradation increases with decreasing pH. The pH stability of pantoprazole was studied at the above-mentioned temperature conditions. The PPZ peaks were analyzed by comparing them with fresh samples and were stable in SIF solution after 24 hours elapsed time at pH 6.8. The obtained degraded peaks in SGF (pH 1) were successfully separated from the PPZ.

Investigating a Simple and Sensitive High-performance Liquid Chromatography Method for Simultaneous Determination of Apigenin, Catalpol, and Gallic Acid Contents in Plantago Lanceolata L. and Plantago Major L.

Investigating a Simple and Sensitive High-performance Liquid Chromatography Method for Simultaneous Determination of Apigenin, Catalpol, and Gallic Acid Contents in Plantago Lanceolata L. and Plantago Major L.

Highly selective and sensitive high performance liquid chromatography method for determination of fumonisins from feed samples with MIL-101 based dispersed micro-solid-phase extraction and precolumn fluorescence derivatization

A selective and rapid high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method for determining fumonisins was established and validated, which based on dispersed microsolid-phase extraction (D-μ-SPE) and precolumn derivatization. The MIL-101 was prepared as sorbents to selectively enrich two fumonisins from feed samples. The obtained extracts were labeled by a novel derivatization reagent 2,5-dioxopyrrolidin-1-yl 4-(1-methyl-1H-phenanthro[9,10-d]imidazol-2-yl)benzoate (MPIBA-Su). There was no fluorescence from fumonisins itself, while their derivatives exhibited considerable fluorescence with a maximum excitation at λex 255 nm and a maximum emission at λem 457 nm. Key factors affecting extraction efficiency and derivatization efficiency were fully optimized. Excellent linearity was achieved with correlation coefficients > 0.9935 under optimal conditions. The detection limits (LODs) were between 2.4 and 3.5 ng·mL−1, and the quantitation limits (LOQs) were between 8.1 and 11.7 ng·mL−1. With recoveries in the range of 83.8% − 94.3%, the established method has successfully been applied to the quantitative analysis of fumonisins in feed samples.

Development and validation of an effective and sensitive technique for nitrate determination in fruits and vegetables using HPLC/PDA.

This study aims to develop an effective and sensitive HPLC (High Performance Liquid Chromatography) method to determine the nitrate concentration in fruits and vegetables (F & V) using a C18 column (ZORBAX Eclipse XDB-C18, 80Å, 250 × 4.6mm, 5μm (Agilent Technologies)) maintained at 40 0C, a mobile phase made up of methanol and buffer (pentane sulfonic acid sodium salt solution), and a Photo Diode Array Detector (PDA) at 225nm. The developed method is validated in terms of selectivity, linearity, accuracy, precision, suitability, the limit of detection (LOD), and the limit of quantification (LOQ) according to the European Union Decision 2002/657/EC. The result revealed that a ratio of 30: 70 of the organic modifier methanol and buffer with pH 2.8 shows the highest efficiency. The calibration curve shows linearity with a correlation coefficient (r) of 0.9985. The LOD and LOQ were found to be 2.26mg/kg and 7.46mg/kg. The recovery was in the range of 98.96-100.21%. Moreover, the greenness assessment scores of different approaches (eco-scale score of 76, AGREE score of 0.71, and few red shades in GAPI portray) were at a very excellent level. Thus, our developed method is fully validated and can determine the nitrate content in F & V.

Rapid Determination of Lignans in Schisandra chinensis by Supramolecular Solvent (SUPRAS)-Based Extraction and High-Performance Liquid Chromatography–Tandem Mass Spectrometry (HPLC-MS)

A supramolecular solvent (SUPRAS)-based sample preparation method was proposed for the determination of lignans in Schisandra chinensis (S. chinensis) fruit. The optimal conditions were: proportion of hexafluoroisopropanol in SUPRAS: 35% (v/v), solid-to-liquid ratio: 20:1 mg/mL, and vortex time: 30 s. Additionally, simple, rapid, and sensitive high-performance liquid chromatography coupled with triple quadrupole mass spectrometry and multiple reaction monitoring was employed to simultaneously quantify seven lignans in S. chinensis. The validation showed that the linearity from 0.01 to 20.83 µg/mL was excellent (all R 2 ≥ 0.99). The lowest limits of quantification were from 0.14 to 17.79 ng/mL. The relative standard deviation (RSD) of the intra-day retention time and peak area were from 0.12% to 0.21% and 2.35% to 6.41%. The RSD of retention time and peak area for the inter-day precision ranged from 0.17% to 0.32% and 3.83% to 7.39%. The average recoveries (80.21%–114.53%) demonstrated good accuracy for all analytes. The developed procedure was employed to determine lignans in processed and raw S. chinensis fruit. The lignans were concentrated in the seeds and the wine-processed material had the highest content. This study provides a reference for the analysis of S. chinensis fruit for lignans.

Development of HPLC-DAD method for the quantification of pentostatin in the fruiting body of Cordyceps militaris

Cordyceps militaris is an important medicinal mushroom in traditional medicine. It contains many bioactive compounds that have applications in medicine, such as cordycepin, adenosine... Recently, through genome analysis, C. militaris has been shown to have the ability to synthesise pentostatin. Pentostatin is an important active ingredient in the production of chemotherapy drugs used in cancer treatment. However, there have been few studies on the development of methods for quantifying pentostatin in C. militaris. In this study, a simple and sensitive high-performance liquid chromatography with diode-array detection (HPLC-DAD) method for the quantification of pentostatin in C. militaris was developed and validated. The chromatographic separations were obtained by an Agilent C18 column (250x4.6 mm i.d., 5 μm particle size) using gradient elution with acetonitrile and water. The flow rate of 0.6 ml/min and detection wavelength of 280 nm were selected. The calibration curve displayed a good linear correlation (R2>0.99). The validation results displayed great accuracy, repeatability, linearity, and selectivity according to The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guideline.

Assessment on compatibility and safety of labels for pharmaceutical packaging

Although the secondary packing materials do not directly contact the finished drug products, compound migration may still happen between them. To ensure drug quality and safety, extractables and leachables of the packing materials should be analyzed. In this study, 2,6-di-tert-butyl-4-methylphenol (BHT) was first found in the labels for pharmaceutical packaging. For the identification of the compound, a strategy combining high performance liquid chromatography (HPLC), ultra-performance liquid chromatography-quadrupole time-of-flight mass (UPLC-Q-TOF-MS) and nuclear magnetic resonance (NMR) spectroscopy was utilized. Afterwards, a effective and sensitive HPLC method for quantification of BHT was developed and validated. Finally, a toxicological risk assessment of BHT was performed to ensure the safety of drugs.

Development of HPLC-UV Method for Simultaneous Determination of Corticosteroid Co-Administered Immune Therapy.

Prednisolone (PDS) has recently been utilized to treat a variety of medical disorders, including autoimmune illnesses and cancer. It is also used to treat coronavirus disease 2019 infection-related respiratory problems. Because it may induce health problems including gastrointestinal lesions and ulceration, it has to be used alongside other drugs like esomeprazole (ESM), which acts as a proton pump antagonist to reduce the probability of ulceration. As a result, the goal of this research is to create an environmentally safe and sensitive high-performance liquid chromatography (HPLC) approach for determining PDS and ESM in their binary combination and spiked human plasma. C8 column (100 × 4.6mm, 5μm) and gradient mobile phase elution were used to separate the studied drugs with ultraviolet recognition at 290nm. Caffeine was utilized as an internal standard to adjust the sample variance. Plasma, caffeine, ESM and PDS all had tR values of 1.4, 3.5, 6.3 and 7.3, respectively. The suggested method's greenness features were evaluated using three greenness evaluation tools: green analytical procedure index, analytical greenness metric approach and analytical eco-scale, and the findings were approved and satisfied. Validation parameters were evaluated in accordance with US-FDA recommendations in order to meet the global desires for biological analysis technique, acceptable limits were obtained.

Application of solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) and comparison of both detection techniques (DAD and FLD) to analyse nesfatin-1 in fetal bovine serum samples

AbstractIn this study, we propose a simple, cost-effective, and sensitive high-performance liquid chromatography with both detection techniques such as diode-array detection and fluorescence detection (HPLC-DAD-FLD) for the determination of nesfatin-1 in fetal bovine serum samples. The limit of detection (LOD) and limit of quantification (LOQ) for nesfatin-1 were set at satisfactory values in the range 0.22–0.35 mg mL−1 and in the range 0.67–1.05 mg mL−1, respectively (at two different wavelengths (DAD) and at four different wavelengths (FLD)). Analyte concentrations were determined as the average value from fetal bovine serum matrix samples. The preliminary results show that the SPE procedure on Isolute Si-TsOH (SCX-3) could be used for further nesfatin-1 analyses in human serum samples. Both the SPE technique, chromatographic analysis with gradient elution mode and detection technique are fast and convenient.

Determination of Pterostilbene in Pharmaceutical Products Using a New HPLC Method and Its Application to Solubility and Stability Samples

The quantification of a natural bioactive compound, pterostilbene (PTT), in commercial capsule dosage form, solubility, and stability samples was carried out using a rapid and sensitive high-performance liquid chromatography (HPLC) approach. PTT was quantified on a Nucleodur (150 mm × 4.6 mm) RP C18 column with a particle size of 5 µm. Acetonitrile and water (90:10 v/v) made up the mobile phase, which was pumped at a flow speed of 1.0 mL/min. At a wavelength of 254 nm, PTT was detected. The developed HPLC approach was linear in 1–75 µg/g range, with a determination coefficient of 0.9995. The developed HPLC approach for PTT estimation was also rapid (Rt = 2.54 min), accurate (%recoveries = 98.10–101.93), precise (%CV = 0.59–1.25), and sensitive (LOD = 2.65 ng/g and LOQ = 7.95 ng/g). The applicability of developed HPLC approach was revealed by determining PTT in commercial capsule dosage form, solubility, and stability samples. The % assay of PTT in marketed capsules was determined to be 99.31%. The solubility of PTT in five different green solvents, including water, propylene glycol, ethanol, polyethylene glycol-400, and Carbitol was found to be 0.0180 mg/g, 1127 mg/g, 710.0 mg/g, 340.0 mg/g, and 571.0 mg/g, respectively. In addition, the precision and accuracy of stability samples were within the acceptable limit, hence PTT was found to be stable in solution. These results suggested that PTT in commercial products, solubility, and stability samples may be routinely determined using the established HPLC method.

The Quantification of Paclitaxel and Its Two Major Metabolites in Biological Samples by HPLC-MS/MS and Its Application in a Pharmacokinetic and Tumor Distribution Study in Xenograft Nude Mouse.

A rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantification of Paclitaxel (PTX), 6α-hydroxypaclitaxel (6α-OHP), and p-3'-hydroxypaclitaxel (3'-OHP) in mouse plasma and tumor tissue. The analytes were separated using a C18 column (50 × 2.1 mm, 1.8 μm), and a triple-quadrupole mass spectrometry device equipped with an electrospray ionization (ESI) source was applied for their detection. PTX, 6α-OHP, and 3'-OHP were extracted from the biological samples with the solid-phase extraction cartridge. The method was fully validated according to the FDA's guidance. The method was linear over the concentration ranges of 0.5~1000.0 ng/mL for PTX and 0.25~500.0 ng/mL for 6α-OHP and 3'-OHP. The precision, accuracy, extraction recovery, and matrix effects were within acceptable limits. The present method was successfully applied to the study of the pharmacokinetics and distribution of PTX, 6α-OHP, and 3'-OHP in the tumors of post xenograft nude mice intravenously injected with PTX solution.

Quantitative Determination of Ascorbic Acid in Herbal Medicinal Products by HPLC

Ascorbic acid (vitamin C) is involved in many vital biochemical processes in the human body. Rose hips are a natural source of ascorbic acid. Rose hips are used in decoctions and many vitamin herbal teas. Russian compendial methods for the quantitative determination of ascorbic acid have certain limitations precluding its objective measurement in herbal drugs, herbal drug preparations, and herbal medicinal products.The aim of the study was to develop an analytical procedure for the quantitative determination of ascorbic acid in herbal drugs, herbal medicinal preparations, and herbal medicinal products using high performance liquid chromatography (HPLC).Materials and methods. The study involved two herbal medicinal products, Rose Hips (rose hips) and Vitamin Herbal Tea 2 (rose hips and rowan fruits), and reference standards for ascorbic acid, rutoside, quercetin, gallic acid, caffeic acid, chlorogenic acid, luteolin-7-glucoside, citric acid, DL-malic acid, thiamine, and pyridoxine hydrochloride. The authors used a 1260 Infinity II chromatograph with a diode array detector by Agilent and an Inertsil ODS-3 chromatographic column (250 mm × 4.6 mm, 5 µm) by GL Sciences. The HPLC system was operated in gradient elution mode, and the detector was set at 244 nm.Results. Ascorbic acid content in herbal drugs, herbal medicinal preparations, and herbal medicinal products can be determined by HPLC. Adequate sample preparation and chromatography conditions allow for inhibiting ascorbic acid oxidation in aqueous solutions for a period sufficient to complete testing (not less than 8 h).Conclusions. The authors developed a highly sensitive and selective HPLC procedure for the quantitative determination of ascorbic acid intended for the standardisation of herbal drugs, herbal medicinal preparations, and herbal medicinal products. The procedure is worthy of inclusion in the Rose Hips and Vitamin Herbal Tea 2 monographs of the State Pharmacopoeia of the Russian Federation. Switching to HPLC should not require lowering the limit for ascorbic acid (not less than 0.2%) established in the Rose Hips and Vitamin Herbal Tea 2 monographs for the titration method. The ascorbic acid content was below this limit in the vast majority of study samples. However, this discrepancy may be explained by the presence of dog rose (Rosa canina) species low in vitamin C, which should normally be used only as choleretics.

Development and validation of a high performance liquid chromatography tandem mass spectrometry method for determination of clenproperol residue in milk, yogurt, sausage and livestock meat

Clenproperol is a β-adrenergic agonist that have a similar chemical structure and physicochemical property to clenbuterol, allowing it easy to be illegally used instead of clenbuterol in zootechnics and sports. This raises the need for monitoring of clenproperol residue in animal-derived foods entering the market destined for human consumption. Thus, a reliable and sensitive high performance liquid chromatography – tandem mass spectrometry (HPLC–MS/MS) method for the detection and identification of clenproperol residue in most commonly consumed animal-derived foods such as milk, yogurt, sausage, swine muscle, bovine muscle and goat muscle samples has been developed. The extraction and clean-up were carried out by employing an ammonium acetate solution and solid phase extraction with mixed-mode cation exchanger (MCX) cartridges. The developed method was fully optimized and successfully validated for all six matrices according to the National Standard of the People's Republic of China GB/T 27417–2017 and was demonstrated to be highly specific and sensitive. Quantitative analysis was performed by means of internal standard calibration using structurally similar clenbuterol-D9 as internal standard. The method presented low limits of detection (0.015–0.06 μg kg−1) and quantification (0.05–0.2 μg kg−1), and good specificity, linearity (R2 ＞0.999), precision and trueness, in terms of repeatability and in-laboratory reproducibility. The recoveries were between 76.1 % and 109.1 % in all matrices studied, with relative standard deviation (RSD) values in the range of 1.2–10.5 %. Furthermore, the method was successfully applied to the analysis of real samples, indicating the suitability of the proposed method for the determination of clenproperol. The developed method could be a valuable tool for control of illegal use of clenproperol in zootechnics.

A high-performance liquid chromatography-tandem mass spectrometry method for quantification of perampanel in human plasma: Effect of concomitant anti-seizure medications on perampanel concentration in patients with epilepsy

Perampanel is a first-in-class α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist and a novel anti-seizure medication. It is currently used as adjunctive treatment for partial seizures in patients over 12 years of age. With the increasing clinical application of perampanel, monitoring its concentration under certain clinical conditions is important. This study developed a rapid and sensitive high-performance liquid chromatography–tandem mass spectrometry method to quantify perampanel in human plasma. Protein precipitation with acetonitrile was performed for sample preparation. Perampanel and perampanel-d5 (internal standard) were analyzed under gradient conditions using a C18 column. The mobile phase was composed of 0.1% (v/v) formic acid in water (solvent A) and 0.1% (v/v) formic acid in acetonitrile (solvent B) at a flow rate of 0.4 mL/min. Mass detection was performed using multiple reaction monitoring in the positive ionization mode. The proposed method was validated over a range of 0.5–500 ng/mL for perampanel. The linearity (r2 value) was higher than 0.999, and the linear equation was y = 0.00116x + 0.0116. The accuracy of the low-, middle-, and high-quality control samples was between 103% and 113%, and the intra- and inter-day precisions were below 6.81%. The quality of the proposed method was evaluated in accordance with the US Food and Drug Administration Bioanalytical Method Validation Guidance for Industry. The plasma concentrations of perampanel in 25 patients were successfully determined to be 38.7–577.7 ng/mL using the validated method.