C18 Column Research Articles

Determination of ADB-BUTINACA in rat plasma by UPLC-MS/MS and its application

AbstractA fast, accurate, sturdy, and sensitive UPLC-MS/MS method was developed to measure the levels of ADB-BUTINACA in rat plasma for a pharmacokinetic study. The ADB-BUTINACA and midazolam (internal standard) were separated on a UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) using a gradient elution of acetonitrile and water (0.1% formic acid) as the mobile phase. ADB-BUTINACA and midazolam were detected in multiple reaction monitoring (MRM) mode for quantitative analysis, the mass detection was performed on a positive electrospray ionization (ESI) source. The calibration curve displayed excellent linearity from 1 to 1,000 ng mL−1, with a lower limit of quantification of 1.0 ng mL−1 and a limit of detection of 0.3 ng mL−1. The precision for both inter-day and intra-day assays was below 14%, while accuracy ranged from 92% to 111%. The method also showed an average recovery between 87% and 90%, with a matrix effect ranging from 104% to 111%. The data was acceptable according to the guidelines of the US Food and Drug Administration (FDA). This newly validated quantitative method successfully supported the pharmacokinetic study of ADB-BUTINACA.

Analytical quality by design-based stability-indicating high performance liquid chromatography method for the estimation of evogliptin tartrate in bulk and tablet dosage form.

The present study utilized Analytical Quality by Design (AQbD) approach to develop a stability-indicating high-performance liquid chromatography (HPLC) method for estimating evogliptin tartrate using design expert software. The key parameters were methodically optimized, contours were plotted, and stability was evaluated using various forced degradation conditions. Using an Agilent HPLC system with a photo diode array (PDA) detector along with Fortis C18 column (250 × 4.6mm, 5μm) effectively separated the drug from its degradants. The mobile phase used was methanol: water (pH adjusted to 3.0, 76:24; v/v) at 0.8mL/min flow rate. Evogliptin was eluted at 2.98 min, at a detection wavelength of 267 nm. The proposed method was found to be specific, precise, linear and robust. The drug was sensitive to acidic, basic, oxidative, thermal, and photodegradation resolving six degradation products. Thus, the developed AQbD-based stability-indicating HPLC method is applicable in analyzing evogliptin in bulk, tablet dosage form and stability samples.

A novel HPLC method for selexipag in human plasma and application to a prototype pharmacokinetic study

AbstractA novel simple and cost effective HPLC technique was presented for the quantification of selexipag (SLP) in human plasma sample and the technique's applicability to a pharmacokinetic investigation. Chromatographic separation was achieved with C18 (5 µm × 4.6 mm × 150 mm) column, at 30 °C with isocratic elution, mobile phase composed of solution A (acetonitrile), and solution B (0.5% formic acid) (65:35 v/v) at flow rate 1.2 mL min−1. The linearity range is 10–150 ng mL−1. As sample preparation step human plasma was precipitated with acetonitrile and the detection was provided at 300 nm. The retention time is 8.20 ± 0.02 min. LOD is found to be 3.3 ng mL−1 for drug. The method was applied to the analysis of SLP in human plasma with good recovery as 97.83%. Validation of the studied methods was carried out according to EMA guideline. The new method applied on a prototype pharmacokinetic study by administration of 800 μg SLP to a healthy volunteer and parameters like AUC0–24, AUC0–∞, Cmax, tmax, and t1/2 were assessed.

The use of an RP-HPLC-UV method for the analysis of oxcarbazepine in the presence of its preservatives; stability studies and application to human plasma samples

AbstractA simple, sensitive, selective, accurate and precise method was developed and fully validated for determination of oxcarbazepine (OXC) in presence of their preservatives and determination of oxcarbazepine (OXC) in human plasma. A reversed phase liquid chromatography (RP-HPLC) with UV detection techniques were applied for separation and quantification of studied drug OXC. Successful separation of the drug from methyl paraben (M.P.), propyl paraben (P.P.) and potassium sorbate (P.ST.) was achieved on a Kromasil C18 column (5 μm particle size, pore size 300 Å, l × I.D. 250 × 4.6 mm). The mobile phase that contain aqueous 0.05M potassium dihydrogen phosphate buffer (pH 7): acetonitrile, (50: 50, %v/v). The method was linear over concentration ranges 5.0–50 μg mL−1 for OXC. Bioanalytical validation of the developed method was carried out according to US-FDA guidelines and revealed a good linear relations over a range of (5.0–50), (0.5–10), (0.05–0.15), and (1.0–10) μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, with a correlation coefficient (R2) of more than 0.999. Limit of detection (LOD) were 1.15, 0.03, 0.01 and 0.04 μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, Intra and inter-day precisions, calculated as percentage relative standard deviation (% RSD), were lower than 2.0%. The developed method can be applied for routine drug analysis, therapeutic drug monitoring and bioequivalence studies through the analysis of plasma samples taken from blood bank.

A green HPLC method for determination of mirtazapine in pharmaceutical products: Development, validation, and greenness assessment

AbstractMirtazapine is an antidepressant medication used to treat the major depressive disorder in adults. In this study, two different chromatographic methods were developed for the determination of mirtazapine in pharmaceutical products. In the first method, An Extend C18 column (250 × 4.6 mm, 5 μm) was used and the temperature was kept constant at 25 °C. The mobile phase was determined as 0.1% formic acid solution and acetonitrile (80/20, v/v), and isocratic elution was applied. The flow rate of the mobile phase was determined as 1.0 mL min−1 and the injection volume was 20 µL. Detection was performed at 291 nm. using a UV detector. In the second method, ethanol was used as the organic modifier. The only difference between these methods was the organic modifier. All other conditions of the methods were the same. Both chromatographic methods were validated by ICH guidelines for various parameters such as selectivity, linearity, accuracy, precision, detection and quantification limit, and robustness. The determination coefficients of chromatographic methods were greater than 0.999 in the concentration range of 5–30 µg mL−1. of mirtazapine. Later, these chromatographic methods were applied to pharmaceutical formulations. Comparison of the obtained results in terms of means was made using Student's (t) test, and comparisons in terms of standard deviations were made using the Fischer (F) test. It was observed that there was no significant difference between these methods. These two methods were then evaluated using the AGREE-Analytical GREEnness metric software. The chromatographic method using ethanol as an organic modifier has been proposed as an excellent eco-friendly and analyst-friendly alternative for the determination of mirtazapine in pharmaceutical formulations.

Determination of morphine, codeine, thebaine, papaverine and noscapine in rat plasma by UPLC-MS/MS

AbstractIn this work, a UPLC-MS/MS assay was established for the determination of morphine, codeine, thebaine, papaverine and noscapine in rat plasma. ACQUITY UPLC BEH C18 column was employed for chromatographic separation with the mobile phase comprised acetonitrile-10 mmol L−1 ammonium acetate aqueous solution (0.05% aqueous ammonia) using gradient elution. Midazolam was used as internal standard (IS). Electrospray ionization (ESI) in positive-ion mode with reaction monitoring (MRM) was used for quantitative analysis. The calibration curves for morphine, codeine, thebaine, papaverine and noscapine demonstrated good linearity (r > 0.995) in the range of 5–500 ng mL−1 for morphine and codeine, and 1–100 ng mL−1 for thebaine, papaverine and noscapine. The intra-day and inter-day precisions of morphine, codeine, thebaine, papaverine and noscapine were within 15%, the intra-day and inter-day accuracies were 89–114%, the recovery was better than 65%, and the matrix effects were 96–112%. The developed UPLC-MS/MS assay was successfully applied in the pharmacokinetics of papaverine and noscapine.

Determination of eight neonicotinoid pesticides in wastewater by solid phase extraction combined with liquid chromatography-tandem mass spectrometry

Neonicotinoid pesticides are a relatively new class of pesticides that have garnered significant attention owing to their potential ecological risks to nontarget organisms. A method combining solid phase extraction with liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) was developed for the rapid and accurate detection of eight neonicotinoid pesticides (dinotefuran, E-nitenpyram, thiamethoxam, clothianidin, imidacloprid, imidaclothiz, acetamiprid, and thiacloprid) in wastewater. The chromatographic mobile phase and MS parameters were selected, and a single-factor method was used to determine the optimal column type, extraction volume, sample loading speed, and pH for SPE. The optimal parameters were as follows: column type, HLB column (500 mg/6 mL); sample extraction volume, 500 mL; sample loading speed, 10 mL/min; and sample pH, 6-8. The matrix effects of the wastewater samples were reduced by optimizing the chromatographic gradient-elution program, examining the dilution factor of the samples, and using the isotope internal standard calibration method. Prior to analysis, the wastewater samples were diluted 5-fold with ultrapure water for pretreatment. Subsequently, 2 mmol/L ammonium acetate aqueous solution containing 0.1% (v/v) formic acid and methanol was used as mobile phases for gradient elution on a ZORBAX Eclipse Plus C18 column (100 mm×2.1 mm, 1.8 μm). The samples were quantified using positive-ion multiple reaction monitoring (MRM) mode for 10 min. Imidacloprid-d4 was used as the isotope internal standard. The SPE process was further optimized by applying response surface methodology to select the type and mass of rinsing and elution solvents. The optimal pretreatment of the SPE column included rinsing with 10% methanol aqueous solution and elution with methanol-acetonitrile (1∶1, v/v) mixture (7 mL). The eight neonicotinoid pesticides showed satisfactory linearity within the relevant range, with linear correlation coefficients (r) all greater than 0.9990. The method detection limits (MDLs) ranged from 0.2 to 1.2 ng/L, and the method quantification limits (MQLs) ranged from 0.8 to 4.8 ng/L. The average recoveries of the eight neonicotinoid pesticides were in the range of 82.6%-94.2% at three spiked levels, with relative standard deviations (RSDs) ranging from 3.9% to 9.4%. Finally, the optimized method was successfully applied to analyze wastewater samples collected from four sewage treatment plants. The results indicated that the eight neonicotinoid pesticides could be generally detected at concentrations ranging from not detected (ND) to 256 ng/L. The developed method has a low MDL and high accuracy, rendering it a suitable choice for the trace detection of the eight neonicotinoid pesticides in wastewater when compared with other similar methods. The proposed method can be utilized to monitor the environmental impact and assess the potential risks of neonicotinoid pesticides in wastewater, thus promoting the protection of nontarget organisms and the sustainable use of these pesticides in agriculture.

Simultaneous determination of 61 hormones in water by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry

Concerns over the emergence of steroid hormones as pollutants in water have grown. Steroid hormone compounds present challenges in the simultaneous detection of total residual hormones owing to their analogous structures and diverse types. In this study, we established a rapid and high-throughput continuous online method based on solid phase extraction (SPE) coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous determination of 61 hormone components, including 48 glucocorticoids, 1 mineralocorticoid, 4 androgens, and 8 progesterones, in water. Various SPE columns were investigated to assess their extraction efficiency for enriching and purifying target compounds in a large sample volume (1 L). An HC-C18 SPE column was selected because of its superior performance. Acetonitrile was used as a washing solution during SPE to ensure that the majority of the tested substances achieved recoveries exceeding 70% and effectively avoid interferences from water-soluble components. Various C8 and C18 columns were tested, and the optimal HPLC conditions for hormone retention were established. We systematically evaluated different UPLC columns and mobile phases, including methanol-water and acetonitrile-water systems with 0.1% formic acid added to the aqueous phase. The optimized UPLC conditions were as follows: BEH C18 column (100 mm×2.1 mm, 1.7 μm); column temperature, 40 ℃; flow rate, 0.3 mL/min; injection volume, 5 μL; mobile phase A: 0.1% formic acid aqueous phase; mobile phase B: acetonitrile. Gradient elution was performed as follows: 0-0.5 min, 30%B; 0.5-15.0 min, 30%B-75%B; 15.0-18.0 min, 75%B-98%B; 18.0-19.0 min, 98%B; 19.0-19.1 min, 98%B-30%B; 19.1-20.0 min, 30%B. Both positive- and negative-ion modes were explored in the UPLC-MS/MS experiment to obtain the full scan of the parent ions, and positive mode was finally selected for electrospray ionization (ESI). Two product ions exhibiting strong signals and minimal interference were selected for quantitative and qualitative ion analyses, using an external standard method for quantification. MS/MS was performed in positive-ion (ESI+) mode with multiple reaction monitoring (MRM) scanning. The MS/MS parameters were as follows: atomizing gas pressure, 379 kPa; curtain air pressure, 241 kPa; spray voltage, 5500 V; desolvation temperature, 550 ℃; collision exit voltage (CXP), 13 V; intake voltage (EP), 10 V; and residence time of each ion pair, 0.5 ms. Other instrument settings, such as the collision energy and declustering voltage, were also optimized. The 61 hormones exhibited excellent linear relationships within their corresponding concentration ranges, with correlation coefficients greater than 0.99. The method detection limits (MDLs) were in the range of 0.05-1.50 ng/L. The average recoveries of the 61 hormones across three spiked levels ranged from 62.3% to 125.2%, with relative standard deviations (RSDs, n=6) of 1.1%-10.5%. Using this method, we successfully detected 10 hormone components (cortisone, fluticasone propionate, ciclesonide, betamethasone dipropionate, clobetasone butyrate, diflucortolone valerate, halobetasol propionate, isoflupredone, difluprednate, and hydroxyprogesterone caproate) in various surface water and groundwater samples collected from the Taihu Basin region. The SPE-UPLC-MS/MS method presented in this paper is simple, highly sensitivity, and exceptionally accurate. Thus, it exhibits promising potential for tracing targeted hormone residues in water and will be of great value in monitoring and ensuring water safety. Finally, a regional analysis was conducted on the hormone levels in water, and suggestions were made for the targeted treatment of hormone residues in future sewage treatment processes.

Identification of chemical components of large-leaf yellow tea by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Large-leaf yellow tea, a slightly fermented yellow tea that is unique to China, has a stronger hypoglycemic effect than other tea varieties, such as green and black tea. Research on large-leaf yellow tea has focused on its hypoglycemic effect owing to the lack of comprehensive techniques to characterize its chemical components; thus, its development and further promotion are limited. Therefore, the development of a reliable analytical method to fully characterize the chemical components of large-leaf yellow tea is urgently required. In this study, a reliable strategy based on the data-acquisition technology of ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q TOF/MS) was established to rapidly screen and analyze the main chemical components of large-leaf yellow tea by combining the information of neutral loss groups and characteristic fragment ions. The chromatographic separation experiments were performed on a Waters ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution using 0.1% formic acid aqueous solution and acetonitrile as the mobile phases. The flow rate was 0.2 mL/min, the sample volume was 2 μL, and the column temperature was 35 ℃. The mass spectral information of the components in a large-leaf yellow tea solution was collected using the full-information tandem MS (MSE) technique in positive and negative ion modes. The specific chemical components of large-leaf yellow tea was identified as follows. First, a self-established database of tea chemical components was constructed based on the literature. The mass spectral cleavage pathways of different types of compounds in large-leaf yellow tea were then sorted using reference substances, and the characteristics of the fragment ions and neutral loss groups were summarized. The precise mass-to-charge ratio of the target chemical components were then obtained based on the mass spectral information. Finally, the structures of the compounds in large-leaf yellow tea were confirmed based on their chromatographic retention times, mass spectral cleavage pathways, characteristic fragment ions, and neutral loss groups. A total of 87 chemical components, including 10 catechins, 32 flavonoids, 16 phenolic acids, 12 tannins, 6 theaflavins, and 11 compounds in other classes, were identified in large-leaf yellow tea. Representative compounds of various classes, including gallocatechin gallate, quercetin, vitexin, gallic acid, chlorogenic acid, 1,3,6-tri-O-galloyl-β-D-glucose, and theaflavin, were selected, and their characteristic fragment ions and neutral loss groups were investigated in detail to reveal the cleavage pathways of different types of compounds in large-leaf yellow tea. The UPLC-Q TOF/MS method established in this study can comprehensively identify the main chemical components of large-leaf yellow tea in a simple, highly sensitive, stable, and reliable manner. This study provides a scientific basis and data support for the discovery of functional ingredients and quality evaluation of large-leaf yellow tea.

Application of a Novel UPLC-MS/MS Method for Analysis of Rivaroxaban Concentrations in Dried Blood Spot and Plasma Samples Collected from Patients with Venous Thrombosis.

Despite a higher safety profile compared to vitamin K antagonists, rivaroxaban therapy is still connected with multiple adverse effects, such as a high risk of bleeding. Thus, therapeutic drug monitoring (TDM) of rivaroxaban concentrations is suggested. An alternative to plasma samples can be dried blood spots (DBS), which minimize the cost of sample storage and transport. In this study, we developed a UPLC-MS/MS method for the analysis of rivaroxaban in DBS and plasma samples. Chromatographic separation was achieved on a Zorbax Eclipse Plus C18 column (2.1 × 100 mm; 3.5 µm, Agilent Technologies Inc., Santa Clara, CA, USA) with a mobile phase consisting of water and acetonitrile, both containing 0.1% formic acid. The analytes were detected using a positive ionization mode by multiple reaction monitoring. We validated the method according to ICH guidelines. The precision and accuracy were satisfactory. Extraction recovery was approximately 57% and 66% for DBS and plasma samples, respectively. A high correlation between rivaroxaban concentrations in plasma and DBS samples collected from patients was confirmed with Deming regression. The suitability of both sampling techniques for the rivaroxaban TDM was also verified by Bland-Altman plots based on DBS-predicted and observed plasma concentrations. In addition, we found a significant relationship between rivaroxaban concentrations and coagulation parameters, including prothrombin time (PT) and international normalized ratio (INR).

A Quality by Design (QBD) Approach for the Development and Validation of RP-HPLC Method for the Quantification of Silymarin Tablet

This study emphasizes the crucial role of Quality by Design (QbD) in developing pharmaceutical procedures, particularly in risk assessment. It demonstrates how QbD principles were applied to create a precise and effective HPLC method for Silymarin Tablets, ensuring consistent quality within specified criteria. The optimized method, developed using a Design of Experiment approach, employs a C18 column (150 mm x 4.6 mm, 5μm) with isocratic elution using a 95:25 ratio of acetonitrile to orthophosphoric acid buffer (pH 3). Peaks were detected using a PDA detector calibrated at 287 nm, with a flow rate of 1.0 mL/min. The column oven temperature was maintained at 25°C, and a 10 μL injection volume was used. Thorough validation, adhering to USP <1225> and ICH Q2 (R1) standards, ensures the method's reliability. Key factors such as accuracy, precision, robustness, limit of detection (LOD), and limit of quantification (LOQ) were comprehensively assessed. The method exhibits exceptional sensitivity, selectivity, efficiency, precision, accuracy, and cost-effectiveness, making it ideal for pharmaceutical analysis of Silymarin tablets. It has been validated to effectively differentiate between marketed products, including those closely resembling the original. This method is intended for routine quality control analysis in the pharmaceutical industry, highlighting its suitability and reliability for ongoing use.

Ultra-performance liquid chromatography-mass spectrometry methods for the determination of the residual quantities of ramipril and hydrochlorothiazide for controlling the cleaning of equipment

Monitoring the completeness of equipment cleaning is essential to prevent cross-contamination of medicinal products. Therefore, it is necessary to develop fast and sensitive methods for studying residual quantities of active ingredients on the surfaces of technological equipment. The aim of the work was to develop and validate analytical methods for the determination of ramipril and hydrochlorothiazide in wash waters by ultra-performance liquid chromatography–mass spectrometry method. Materials and methods. In the study, standard samples of ramipril (USP RS) and hydrochlorothiazide (USP RS), as well as class A reagents, were used. Samples were analysed on a liquid chromatograph with an MS detector (Agilent 6420 and Waters Xevo TQD ACQUITY). We used the Kinetex C18 column (2.1 mm × 30 mm × 1.7 μm); mobile phase – 0.1% formic acid solution in deionised water – Acetonitrile (ratio 73:27 for the determination of ramipril and 91.5:8.5 for the determination of hydrochlorothiazide); mobile phase rate of 0.4 mL/min for the determination of ramipril and 0.35 mL/min for the determination of hydrochlorothiazide; column temperature 45 °C for the determination of ramipril and 40 °C for the determination of hydrochlorothiazide, ionisation mode - electric spray in positive mode; The detection parameters are the mode of registration of the daughter ion 417 → 234 m/z for the determination of ramipril and 298 → 281 m/z for the determination of hydrochlorothiazide. Results and discussion. Methods for the determination of ramipril and hydrochlorothiazide in wash waters by ultra-performance liquid chromatography–mass spectrometry have been developed. The developed methods have sufficient linearity, correctness and precision. The sensitivity of the techniques was confirmed at the level of 0.0026 μg/ml. The techniques can be used in the concentration range of 0.0026 – 0.0255 μg/ml Conclusions. Analytical methods for determining ramipril and hydrochlorothiazide in wash waters have been developed and validated.

Efficacy of the peak area method of high-performance liquid chromatography (HPLC) analysis: The separation, identification, and quantification of phytochemical compounds of Moringa oleifera

The quantification and identification of phytochemical compounds in Moringa oleifera have received significant attention due to their potential health benefits. High-Performance Liquid Chromatography (HPLC) has become a widely used method for analyzing these phytochemicals due to its speed, adaptability, and effectiveness. However, there is a need to improve these methods to achieve more accurate quantification and understanding of these compounds. This study aims to assess the effectiveness of the peak area method in HPLC for the separation, identification, and quantification of phytochemical compounds in Moringa oleifera leaves. The main goal of the study is to use the peak area method within HPLC to measure the concentration of various phytochemical compounds in Moringa oleifera leaves. This method offers a more reliable measurement than peak height, allowing for comparison of different components' concentrations within or between samples, which is important for trace analysis in various applications. The methodology involved collecting and preparing Moringa oleifera leaves from five regions: Nigeria, Ghana, Haiti, India, and Texas, USA. The leaves were dried, ground, and extracted using methanol and ethanol. The extracts were then analyzed using HPLC, with the peak area method utilized to quantify the phytochemical compounds. The HPLC system utilized a Nucleosyl C18 column with a UV-vis diode-array detector, and the separation process was monitored at 332 nm. Key findings of the study indicated that chlorogenic acid, rutin, ferulic acid, luteolin, apigenin, and kaempferol were successfully separated, identified, and quantified from Moringa oleifera leaves using the peak area method in HPLC. Chlorogenic acid had a retention time of 15.759 minutes and a peak area of 170,844, indicating it is more polar and present in significant quantities. Rutin followed with a retention time of 16.919 minutes and a peak area of 115,599. Ferulic acid was the most abundant compound, with a peak area of 422,129 and a retention time of 17.965 minutes. Luteolin, with a peak area of 235,655 and a retention time of 19.777 minutes, was also present in considerable amounts. Apigenin and kaempferol showed retention times of 20.840 minutes and 21.039 minutes with peak areas of 343,378 and 197,585, respectively. The study also compared the extraction efficiencies of 70% ethanol and 80% methanol, finding that methanol was significantly more effective, especially for highly polar compounds like chlorogenic acid, luteolin, and rutin, with peak areas being 74% to over 1100% higher than those observed with ethanol. The study concluded that the peak area method in HPLC is a highly effective tool for the separation, identification, and quantification of phytochemical compounds in Moringa oleifera leaves. It recommended further optimization of the HPLC method and exploration of pharmacological properties of these phytochemical compounds for nutraceuticals and pharmaceuticals.

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.

A novel QbD HPLC approach for the concurrent analysis of amoxicillin, amprolium, and ethopabate in food samples and dosage forms

A simple, rapid, and sensitive reversed-phase HPLC method coupled with photodiode array detection (PDA) was developed for the simultaneous estimation of three co-administered antibacterial drugs, amprolium, ethopabate, and amoxicillin for the first time. An analytical quality-by-design (QbD) approach was adopted to optimize the developed approach. A two-level full factorial design (25 FFD) was implemented to optimize how variable factors affected chromatographic responses. On a Hypersil BDS C18 column, the chromatographic separation was carried out using isocratic elution at 40.1 °C. The mobile phase consisted of methanol: potassium phosphate buffer containing 5.76 mM heptane sulphonate (9.05 mM; pH 3.32, 44.8:55.2 % v/v) pumped at a flow rate of 0.8 mL/min and an injection volume of 20.0 μL. In less than 7 min, the suggested method was able to separate the ternary mixture with a challenging ratio of 1: 15.6: 1 for amoxicillin, amprolium, and ethopabate, respectively. The calibration curves showed excellent linearity over the concentration ranges of 0.50–30.0, 0.30–30.0, and 0.05–20.0 μg/mL, respectively. Recovery percentages ranged from 90.30 % to 111.13 % with %RSD less than 2 % were obtained upon spiking to chicken tissues, liver, and egg samples, indicating the suitability of the proposed method for determining of the studied drugs in complicated food matrices. Furthermore, the proposed method was successfully applied to determine the studied drugs in their commercial formulations. Full validation was carried out according to ICHQ2 (R1) guidelines. Finally, the method's greenness and ecofriendliness were evaluated using various metrics tools, including the Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE).

Stability Indicating Method Development and Validation for the Simultaneous Estimation of N-Acetylcysteine and Acebrophylline in Tablet Dosage form by RP-HPLC

A quick, accurate, precise Stability indicating method for Simultaneous estimation of N-Acetylcysteine and Acebrophylline in Tablet dosage form was developed and validated. Chromatogram was run on Waters C18 (150 x 4.6 mm, 2 μm) Column. Mobile phase containing OPA Buffer and Methanol taken in a ratio of 10:90 % v/v was pumped at a flow rate of 1.5 mL/min through column. Cushion utilized in this strategy was OPA. Column temperature was kept at 35°C. Injection volume was 5 μL and Run time was 5 minutes. Sample was scanned at 285 nm. RT’s of N-Acetylcysteine and Acebrophylline were found to be 2.646 min and 2.117 min respectively. The developed method was validated and was found to be Accurate, Precise and Linear over the Concentration Range of 25 % to 175 % of Test concentration. Retention time and Runtime are less and the method was properly validated so this method can be utilized for routine analysis and stability studies of Assay of N-Acetylcysteine and Acebrophylline in Tablet dosage form in industries.

MonoTip C18 pipette tip solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry enables rapid and automated therapeutic drug monitoring of tyrosine kinase inhibitors

This work presents an advanced automated monolithic C18 pipette-tip solid-phase extraction (PT-SPE) method seamlessly integrated with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for precise therapeutic drug monitoring of eleven tyrosine kinase inhibitors (TKIs) in biological samples. Commercially available MonoTip C18 columns facilitate superior extraction efficiency and selectivity from complex biological matrices owing to their large surface areas and enhanced mass transfer capabilities. The sample preparation process, conducted by aspirating and dispensing solutions using a pipettor, completes the overall extraction process within 3 min. The method validation demonstrated excellent linearity within the range of 0.2/0.5/0.8 to 200 ng/mL, with detection limits ranging from 0.049 to 0.206 ng/mL. The method exhibited outstanding accuracy and precision, with intraday relative recovery rates ranging from 96.3 % to 115.0 % and interday recovery rates ranging from 95.0 % to 115.7 %, with coefficient of variation values consistently below 13.8 %. The proposed method is distinguished by its exceptional efficiency, reduced solvent use, enhanced environmental sustainability, and streamlined automation—key advantages in the realm of clinical therapeutic drug monitoring of TKIs. Overall, the MonoTip C18 PT-SPE technique, coupled with LC-MS/MS, offers a formidable, eco-friendly, and effective strategy for the TDM of TKIs, marking a significant advancement in the field.

Silver Core Coated with Molecularly Imprinted Polymer as Adsorbent in Pipet-Tip Solid Phase Extraction for Neonicotinoids Determination from Coconut Water.

In this work, we report an innovative adsorbent named Ag-MPS@MIP that has a core@shell structure, i.e., silver nanoparticles modified with 3-methacryloxypropyltrimethoxysilane as the core and molecularly imprinted polymer based on methacrylic acid as its shell. Thiamethoxam, imidacloprid, and acetamiprid were extracted from coconut water samples using Ag-MPS@MIP in pipet-tip solid phase, prior to high-performance liquid chromatography analysis. The separation was carried out on isocratic mode using a mobile phase consisting of C18 column (Phenomenex, 150 mm × 4.6 mm, 5 μm), ultrapure water acidified with 0.3% phosphoric acid:acetonitrile (78:22, v/v), flow rate at 1.0 mL min-1, injection volume of 10 μL, temperature of 25 °C, and wavelength at 260 nm. The adsorbent and precursor materials were properly characterized by different instrumental techniques. The main factors affecting the recovery of analytes from coconut water samples by pipet-tip solid phase were optimized, such as sample volume (250 μL), sample pH (pH = 5.0), ionic strength (1%, m/v), washing solvent (300 μL ultrapure water), volume and type of eluent (500 μL methanol), amount of adsorbent (15 mg), cycle of percolation-dispensing (1×), and reuse (5×). Thereby, the neonicotinoids presented extraction recoveries between 82.80 and 96.36%, enrichment factor of 5, linearity ranged from 15 to 4000 ng mL-1, correlation coefficient (r) > 0.99, limit of detection of 5 ng mL-1, satisfactory selectivity, stability, and proper precision (RSD%: 0.52-9.64%) and accuracy (RE%: -5.19-6.45%). The method was successfully applied to real samples of coconut water.

Development and validation of the method of quantification of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites in laboratory animal plasma

Introduction. The study of the systemic exposure of a new original drug is an essential part of its preclinical study. 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide is a new selective carbonic anhydrase II inhibitor for the treatment of open-angle glaucoma. Methods for the quantitative determination of this compound and its N-hydroxy- and N-acetyl metabolites in the plasma of laboratory animals have not been previously developed.Aim. Development and validation of a method of quantitative determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide (M1) and N-acetyl-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide (M2) in rat and rabbit blood plasma by HPLC-MS/MS.Materials and methods. Protein precipitation by methanol was applied for sample preparation. 5-[2-(morpholine-4-carbonyl)-1,3-oxazole-5-yl]-thiophene-2-sulfonamide was used as an internal standard. A 5 % aqueous solution of ascorbic acid was added to the plasma samples at volume ratio 1 : 2 to prevent decomposition of N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide. The combination of sodium fluoride and potassium oxalate was selected as an anticoagulant. Chromatographic separation was performed on Zorbax Eclipse Plus C18 column (150 × 3.0 mm, 3.5 µm) with Zorbax Eclipse Plus C18 pre-column (12.5 × 2.1 mm, 5.0 µm) using a mobile phase based on a 0.1 % aqueous solution of formic acid and methanol. Mass spectrometric detection was carried out in the MRM mode using electrospray ionization in negative polarity. The method was tested during a pharmacokinetic study of a 1 % ocular suspension of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide on 6 Wistar rats. Blood samples were collected before administration, as well as 30 min, 1 h, 1 h 30 min, 2 h, 3 h, 4 h, 6 h, 8 h, 12 h, 24 h, 48 h, 72 h, 144 h, 216 h after administration. The non-compartment approach was used for calculation pharmacokinetic parameters.Results and discussion. The developed method has been validated in parameters of selectivity, calibration curve, accuracy and precision, matrix effect, dilution integrity, carry over, reinjection reproducibility, stability. The analytical range of determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide in plasma was 10–4000 ng/ml, M1 – 1.0–400.0 ng/ml, M2 – 0.1–40.0 ng/ml. The selected combination of anticoagulant and stabilizer solution allows storage of plasma samples in freezing chamber for 28 days.Conclusion. The developed method has been fully validated and confirmed its suitability for quantitative determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites in the blood plasma of laboratory animals. The method has been successfully used for pharmacokinetic study of 1 % ocular suspension of the drug.

Chromatographic fingerprinting of ipratropium and fenoterol in their novel co-formulated inhaler treating major respiratory disorders; application to delivered dose uniformity testing along with greenness and whiteness assessment

Ipratropium bromide (IPR) and fenoterol hydrobromide (FEN) have recently been combined in a promising inhaler to treat two prevalent inflammatory illnesses of the airways: bronchial asthma and chronic obstructive pulmonary disease (COPD). The necessity for a single, sensitive, and trustworthy analytical approach to cover the diverse and necessary tests of in-vitro and in-vivo studies is greatly grown with the rising production of new fixed combinations. Two novel, selective and environmentally friendly LC techniques were developed in order to guarantee precise measurement of IPR and FEN in their challenging formulation. The initial technique involved high-performance thin-layer chromatography (HPTLC) in conjunction with densitometric quantification. Chromatographic separation was attained on HPTLC plates utilizing ethyl acetate - ethanol - acetic acid (5.0:5.0:0.1, by volume) as a developing system. Densitometric quantification of the separated bands was carried out at 220.0 nm over concentration ranges of 0.50–15.0 µg/band for IPR and 0.50–12.0 µg/band for FEN. High-performance liquid chromatography (HPLC) paired with diode array detection (DAD) was the core of the second technique. The optimized separation was achieved on a Zorbax SB C18 (150 × 4.6 mm, 5 μm) column with a combination of 10.0 mM potassium dihydrogen orthophosphate, pH 5.0 ± 0.1, adjusted with o-phosphoric acid and methanol (70:30, v/v) as the mobile phase and pumped at flow rate of 1.0 mL/min. The peaks were monitored at 220.0 nm using diode array detection, achieving linearity range of 5.0–200.0 µg/mL for both drugs. The ICH criteria have been verified and both methods have been confirmed to be valid, and successfully applied for assay the cited drugs in the Atrovent® comp HFA metered dose inhaler as well as delivered dose uniformity testing of the final product. Finally, whiteness appraisal and several state-of-the-art green evaluation metrics were applied to evaluate the sustainability of the proposed methods. The suggested approaches produced promising results and are the first simple and sustainable methodologies for the simultaneous quantification of both drugs in different real samples, all of which strongly suggest their application in quality control laboratories.