Isocratic System Research Articles

Development and Validation of an Ion-Pair HPLC-UV Method for the Quantitation of Quinoline and Indoloquinoline Alkaloids in Herbal and Pharmaceutical Antimalarial Formulations

Quinine- and cryptolepine-based antimalarials serve as valuable alternatives to artemisinin-based combination therapies (ACTs) in Ghana. Their use, however, is associated with adulteration and substandard quality challenges. An HPLC method targeting quinoline and indoloquinoline antimalarial alkaloids was developed, validated, and applied to evaluate herbal and pharmaceutical antimalarial formulations (HPAFs) and starting materials (APIs). The separation/quantitation of the alkaloids (including quinine, quinidine, cinchonine, cinchonidine, dihydroquinine, dihydroquinidine, and cryptolepine) was achieved on a Zorbax SB-CN column (250 mm × 4.6 mm, 5 μm), with an isocratic elution system of methanol: trifluoroacetic acid (0.1%, v/v) (15 : 85, v/v) at 1.5 mL/min and 223 nm. Method validation was according to ICH Q2(R1) guidelines. It was then used to assess the quality of APIs (n = 3) and HPAFs (n = 44) including quinine-based pharmaceutical antimalarial formulations (QBPAFs) (n = 23) and herbal antimalarial products (HAMPs). The method was found to be specific, selective, accurate, precise, and robust toward the alkaloids with linearity achieved within specified concentration ranges (r2 > 0.995 for all analytes). Analyte stability ranged between 6 and 12 hours. All the APIs contained quinine <99.0%–101.0%, with dihydroquinine and cinchonidine at levels compliant with the established acceptance criteria. The QBPAFs had quinine content ranging between 50.2% and 151.2%, with 43.5% (n = 10/23) of them complying with the acceptance criteria. The related alkaloids observed in the QBPAFs included quinidine (56.5%, n = 13/23), dihydroquinine (100%, n = 23/23), dihydroquinidine (21.7%, n = 5/23), cinchonine (17.4%, n = 4/23), and cinchonidine (95.7%, n = 22/23). For the HAMPs, 81.0% (n = 17/21) were adulterated with quinine (0.59 ± 0.04 mg/10 mL–86.03 ± 0.02 mg/10 mL). Cryptolepine was identified in 19% (n = 4/21) of the HAMPs with concentration ranging between 43.99 ± 0.43 μg/mL and 747.86 ± 0.34 μg/mL. In conclusion, the application of the ion-pair HPLC method targeting quinoline and indoloquinoline antimalarials has demonstrated the presence of quality and poor-quality HPAFs on the Ghanaian market.

Estimation of zorifertinib metabolic stability in human liver microsomes using LC–MS/MS

Zorifertinib (AZD-3759; ZFB) is a novel, potent, oral, small molecule used to treat non-small cell lung cancer. ZFB is an epidermal growth factor receptor inhibitor that is capable of crossing blood–brain barrier. The in silico metabolic software used for ZFB metabolic stability prediction was the StarDrop software package (WhichP450 module). An LC-MS/MS analytical method (fast and accurate) was established for ZFB quantification in human liver microsomes (HLMs) in order to estimate its metabolic stability. ZFB and encorafenib (ENF) (internal standard; IS) were separated through the use of an isocratic mobile phase system with a C8 stationary phase column. The LC-MS/MS method for ZFB exhibited linearity in the range of 5 ng/mL to 500 ng/mL in HLMs matrix with a linear regression equation: y = 0.2438x - 0.341 (R² = 0.9992). The limit of quantification (LOQ) was 3.78 ng/mL confirming the LC-MS/MS method sensitivity. The inter- and intraday accuracy and precision were less than 9.56% confirming the reproducibility of the LC-MS/MS method. The intrinsic clearance and in vitro half-life of ZFB were 32.5 µL/min/mg and 21.33 min, respectively. ZFB exhibited a moderate extraction ratio that revealed good bioavailability. Literature review demonstrated that the developed analytical method is the first developed LC-MS/MS method for determining ZFB metabolic stability.

Determination of dehydroepiandrosterone in dietary supplements by reversed-phase HPLC


 
 
 
 Purpose: To develop a reversed phase high performance liquid chromatography (HPLC) method for the determination of dehydroepiandrosterone (DHEA) in dietary supplements.
 Methods: A reversed-phase high performance liquid chromatography (HPLC) method was developed for the determination of DHEA in dietary supplements. An isocratic system consisting of methanol and water (70:30 v/v) was run at a flow rate of 1 mL/min on a C18 HPLC column to achieve the separation. The method was validated with regard to linearity, intra-day and inter-day precision, and limits of both detection and quantification.
 Results: The method achieved a retention time of 10.8 min, a resolution of 4.12, a detection limit (LOD) of 50 ng/μL, a quantification limit (LOQ) of 166.7 ng/μL and a label claim of 108.6 % with a relative standard deviation (RSD) of 0.38 % over a range of 0.0625 – 0.50 mg/mL with a correlation coefficient of 0.9997.
 Conclusion: The method is simple, cost effective, time-saving and reliable for determining DHEA when compared to other reported methods in literature. Thus, it will be of benefit to manufacturers of this dietary supplement to adopt the method for quantitative laboratory analysis.
 
 
 

Development and validation of a HILIC-HPLC-ELSD method for simultaneous determination of glucosamine hydrochloride and chondroitin sulfate in dietary supplements

The objective of the present study is to develop and validate a simple, selective and accurate hydrophilic interaction liquid chromatography - a high performance liquid chromatography incorporating an evaporative light scattering detector (HILIC-HPLC-ELSD) method for simultaneously determining glucosamine hydrochloride and chondroitin sulfate in dietary supplements. The chromatographic separation was carried out on a ZIC-HILIC column (150 mm x 4.6 mm x 5µm) in isocratic system mode with a mobile phase of acetonitrile, 30 mM ammonium formate and water (77:20:3, v/v/v) at pH 4.5, a column temperature of 35°C, a flow rate of 1 mL.min-1, and an injection volume of 5 µL. An evaporative light scattering (ELS) detector was used. Effective separation was achieved by means of analyte resolution of more than 1.5 with an analysis run time of approximately 20 minutes. The linearity of glucosamine hydrochloride and chondroitin sulfate ranged from 0.4 to 2.5 mg.mL-1. The limits of the detection and quantification of glucosamine hydrochloride were 20 and 80 mg.mL-1 respectively, while for chondroitin sulfate they were 80 and 400 mg.mL-1. All validation parameters satisfied the acceptance criteria in accordance with International Conference on Harmonisation (ICH) guidelines. The method was successfully applied to the assay of commercial dietary supplement samples.

Development of UPLC-MS/MS method and its pharmacokinetic application for estimation of sertraline in rat plasma

The current research aims to develop a rapid, sensitive and robust UPLC-MS/MS method for quantitative estimation of sertraline in rat plasma following oral administration of lipid-based formulation. Different types of isocratic systems were tried for optimization of mobile phase to attain good resolution and appropriate retention time. The multiple reaction monitoring transitions of m/z 306.3 → 159.1 and 515.2 → 276.1 were used to quantify sertraline and internal standard, respectively. The method was validated for different parameters as per the guideline of the United States Food and Drug administration (USFDA). The validated linearity range of sertraline was found to be 1-1,00 ng/mL in rat plasma with 0.1 ng/mL as lower limit of quantification. The intra-day and inter-day precision (RSD%) were within 7.6-10.6% and the accuracies (RE%) were ± 8.0%. The results showed a good percentage recovery of analytes within acceptance limit. No significant degradation of drug in plasma was observed during the stability study. The method demonstrated short analytical run time (< 3 min), low sensitivity (0.1 ng/mL) and requirement of small amount of plasma (50 µL) for extraction procedure.Overall, this method•Results in an optimized and validated assay for estimation of sertraline in plasma.•Offers a cost effective mobile phase with excellent linearity, sensitivity, accuracy, and precision. The method suggested its application in pharmacokinetic study of sertraline administered via oral route.•The method can be used for therapeutic drug monitoring in drug designing. The method can also be used for toxicity and bioequivalence studies.

Analysis of Ethyl p-Methoxycinnamate from Kaempferia galanga L. Extract by High Performance Liquid Chromatography

Ethyl para-methoxycinamate (EPMS) is a major compound of Kaempferia galanga L that has anti-inflammatory effect. The purpose of this study was to determine of EPMS in Kaempferiae galanga L rhizome extract by High Performance Liquid Chromatography (HPLC) and evaluated the performance of the analysis. This study included determination of system suitability, accuracy, precision, linearity and range, limit of detection (LOD) and Limit of quantitation (LOQ) and selectivity. The results of system suitability test HPLC System for EPMS analysis were as follows isocratic elution system of a mobile phase mixture of methanol: water (70:30) containing 0.1% TFA, uv detector at a wavelength of 308 nm using column C18 (150 × 4, 6mm, 5μm) flow rate 1 ml / min. From the analysis, it was found that the average EPMS content was 78.74%. Then method had linear concentration range from 5-360 ppm, with R ² = 0.9999. The LOD and LOQ were 7.0722 ppm and 21.4311 ppm respectively. The accuracy of this method that represented by % recovery was 98.02% - 101.26%. The precision of this method that expressed by Relative Standard Deviation (RSD) was 1.57%. The selectivity of this method that showed by resolution value was 2.6. Based on the results of the system suitability test and analysis performance evaluation,all parameters met the requirements.

Reversed-Phase Liquid Chromatographic Internal Standard Method Using Losartan Potassium for Quantitative Estimation of Ivabradine Hydrochloride in Pharmaceutical Tablet Dosage Form and Plasma

A reversed-phase liquid chromatographic method for ivabradine hydrochloride using Diode Array Detector (DAD) and internal standard technique was developed and validated according to ICH and SWGTOX guidelines. The prime objective of this study was to develop a precise and accurate method that can be equally applicable to biological (plasma) as well as non-biological (active pharmaceutical ingredient and pharmaceutical tablets) matrices. Losartan potassium was used as an internal standard due to its easy availability. After liquid-liquid extraction using acetonitrile, the ivabradine hydrochloride and internal standard were chromatographed on Agilent 1200 series HPLC system equipped with DAD detector, auto-sampler and chemstation software. Analytical separation was achieved on Agilent C-18 (5µm, 25cm x 4.6mm) reversed-phase column at 30°C column oven temperature, 10μL injection volume and 286nm wavelength. Isocratic mobile phase system comprised of 60:40 v/v ratio of HPLC grade methanol and water adjusted to pH 6.8 using orthophosphoric acid was employed with 1mL/min flow rate. The method linear range was 0.025-3µg/mL (25-3000ng/mL) for pharmaceutical tablets and plasma with the coefficient of linearity ranged 0.997-0.999. Results for precision, accuracy, recovery, stability and matrix effect studies were within acceptable limits for both plasma and tablets. Method was successfully applied to the commercial tablet products and patient plasma samples to estimate the amount of ivabradine hydrochloride.

Development of a simple method for measuring tedizolid concentration in human serum using HPLC with a fluorescent detector.

The objective of the present study was to develop a method to measure tedizolid (TZD) concentration for studying target concentration intervention, pharmacokinetics, and pharmacodynamics of TZD. We established a high-performance liquid chromatography-fluorescence detector assay to measure the TZD concentration in serum for clinical application. Chromatographic separation was carried out on a 5 μm octadecyl silane hypersil column 150 mm × 4.6 mm. The mobile phase consisted of 0.1 M phosphoric acid and methanol (60:40, pH 7.0). Detection was performed at 300 nm and 340 nm for the excitation and emission wavelengths, respectively. The average retention times of TZD and the internal standard were 12.9 and 8.8 min, respectively. High linearity was exhibited over a concentration range of 0.025 to 10.0 μg/mL for TZD (R2 > 0.999). The intra- and inter-assay accuracies of TZD were 99.2% to 107.0% and 99.2% to 107.7%, respectively. The lower limit of quantitation and the lower limit of detection for TZD measurement were 0.025 and 0.01 μg/mL, respectively. The extraction recoveries of TZD were 100.4% to 114.1%.The high-performance liquid chromatography method developed in this study could separate the analytes with a single eluent (isocratic system), within a total run time of 15 min. Both TZD and IS were well separated, without interference from the peaks. Sharp peaks were observed in the chromatograms; problems such as double peaks, shoulder peaks, and broadened peaks were not observed. The proposed method showed acceptable analytical performance and could be used to evaluate serum TZD concentrations in patients.

LC-MS/MS Estimation of Rociletinib Levels in Human Liver Microsomes: Application to Metabolic Stability Estimation.

BackgroundRociletinib (CO-1686; RLC) is a new, small molecule that is orally administered to inhibit mutant-selective covalent inhibitor of most epidermal growth factor receptor (EGFR)-mutated forms, including T790M, L858R, and exon 19 deletions, but not exon 20 insertions. Non–small-cell lung cancer (NSCLC) with a gene mutation that encodes EGFR is sensitive to approved EGFR inhibitors, but usually resistance develops, which is frequently mediated by T790M EGFR mutation. RLC is an EGFR inhibitor found to be active in preclinical models of EGFR-mutated NSCLC with or without T790M.MethodsIn silico drug metabolism prediction of RLC was executed with the aid of the WhichP450 module (StarDrop software package) to verify its metabolic liability. Second, a fast, accurate, and competent LC-MS/MS assay was developed for RLC quantification to determine its metabolic stability. RLC and bosutinib (BOS) (internal standard; IS) were separated using an isocratic elution system with a C18 column (reversed stationary phase).ResultsThe developed LC-MS/MS analytical method showed linearity of 5–500 ng/mL with r2 ≥ 0.9998 in the human liver microsomes (HLMs) matrix. A limit of quantification of 4.6 ng/mL revealed the sensitivity of the analytical method, while the acquired inter- and intra-day accuracy and precision values below 4.63% inferred the method reproducibility. RLC metabolic stability estimation was calculated using intrinsic clearance (20.15 µL/min/mg) and in vitro half-life (34.39 min) values.ConclusionRLC exhibited a moderate extraction ratio indicative of good bioavailability. The developed analytical method herein is the first LC-MS/MS assay for RLC metabolic stability.

Application of RP-HPLC Technique for development of Analytical method for Validation of Metformin hydrochloride from Bulk drug and Dosage form

A Novel Reverse Phase Liquid Chromatographic Method was developed and validated for estimation of metformin hydrochloride in its dosage form i.e. tablets. The reverse phase HPLC analysis was carried out on isocratic system. The column was Hypersil BDS C18 (150mm x 4.6mm, 5µm) with ambient temperature. The mobile phase consisted of buffer: methanol in proportion 90:10 % (v/v). The flow rate was maintained at 1.0ml/ min. The detection was carried out at wavelength 230nm. The method was validated as per ICH guidelines for system suitability, linearity, accuracy and precision. The linear ranges were 50-150µg/ml for metformin hydrochloride, The accuracy and precision were found to be well within the acceptable limit. The method was successfully applied for determination Metformin hydrochloride in dosage form with good recoveries.

In Vitro Culture of Rosmarinus officinalis L. in a Temporary Immersion System: Influence of Two Phytohormones on Plant Growth and Carnosol Production.

Emerging infectious diseases have become a major global problem with public health and economic consequences. It is an urgent need to develop new anti-infective therapies. The natural diterpene carnosol exhibit a wide variety of interesting antibacterial and antiviral properties, and it is considered a theoretical inhibitor of COVID-19 Mpro. However, this compound is present in the family Lamiaceae in low quantities. To obtain carnosol in concentrations high enough to develop pharmacological studies, we evaluated the efficiency of a micropropagation protocol of Rosmarinus officinalis using a solid medium and a temporary immersion system (TIS), as well as the effect of 6-benzylaminopurine (6-BAP) and α-naphthaleneacetic acid (NAA) on the growth of shoots. Moreover, we developed and validated an analytical method to quantify carnosol using the H-point standard additions method in the high-performance liquid chromatography diode array detector (HPLC-DAD). After 30 days of culture, TIS produced the maximum number of shoots per explant (24.33 ± 1.15) on a liquid medium supplemented with 6-BAP at 5.0 mg L−1. Next, we also evaluated the effect of immersion time and frequency for TIS. After 72 days of culture, the best results were obtained with an immersion cycle of 1 min every 12 h, yielding 170.33 ± 29.40 shoots. The quantification of carnosol on the samples was performed at a flow rate of 1.2 mL min−1 using binary isocratic mobile phase system 60:40 (v/v) 10 mM formic acid (pH 3.0) (A) and acetonitrile (B) on a reverse-phase column. The content of carnosol in the in vitro cultures was around 8-fold higher than in the wild plant. The present study represents an efficient alternative method to obtain carnosol for its pre-clinical and clinical development.

Stability Indicating RP-HPLC Method Development and Validation for the Determination of Solifenacin Succinate in Bulk and its Pharmaceutical Formulation

The current work aims to establish a novel and advanced reverse phase isocratic liquid chromatography system followed by validation and to conduct stability analysis in active pharmaceutical ingredients and formulations for the quantification of Solifenacin Succinate. The optimized elution was achieved with column Sunfire C8 (4.6 x 150mm, 5µm), using the mobile phase of Buffer: Methanol: Acetonitrile in the composition ratio of 45:45:10 v/v. The wavelength of detection was selected as 220nm with 1.0ml/ min flow rate and 30μl injection volume. The retention time of Solifenacin Succinate was found 2.94 min respectively. The method developed has been validated for various analytical parameters according to ICH guidelines. The Linearity was attained at 20 to100 μg/ml of concentration range. The established method was proved as reproducible. The Assay was obtained as 100.40%. The degradation studies were carried out at all degradative conditions and the results of degradation studies denote that the current method was specific, reliable, and economical. Hence, the developed method can be applied for the qualitative and quantitative determination of the selected drug and its commercial formulations.

Determination of Zeaxanthin Dipalmitate and 2-O-( β -D-glucopyranosyl) Ascorbic Acid in Fruit of Lycium barbarum L.

Objective: To establish LC methods for zeaxanthin dipalmitate and 2-O-(β-D-glucopyranosyl) ascorbic acid determination in the fruit of Lycium barbarum L. Methods: For the HPLC analysis of zeaxanthin dipalmitate, the test was performed on a Luna C18 (2) column (4.6 mm×250 mm, 5 μm) with the column temperature at 25 ℃. The isocratic elution was adopted with the mobile phase of acetone/MeOH 55:45(V/V) at a flow rate of 1.0 mL·min−1, and UV detection was performed at 450 nm. UPLC analysis of ascorbic acid was carried out on Torus TM Diol Column (3 mm×100 mm, 1.7 μm) at the temperature of 40 ℃. An isocratic system was also used at which the mobile phase (flow rate of 0.4 mL/min) consisting of acetonitrile (solventA) and 66.7 mmol/L ammonium acetate (solvent B) was set as 85% A and 15% B. UV detection wavelength was set at 260 nm. Results: The linear range of zeaxanthin dipalmitate and 2-O-(β-D-glucopyranosyl) ascorbic acid were 0.01~0.1 mg/mL and 3.125~100 μg/mL, with the correlation coefficient being 0.9990 and 1.0000, the average recovery was 99.44% and 96.30%, while the RSD was 4.04% and 3.61% respectively. In 22 batches of L. barbarum samples, the contents of zeaxanthin dipalmitate and 2-O-(β-D-glucopyranosyl) ascorbic acid were up to 0.51% and 1.33%, respectively. Conclusion: The two methods were accurate and reliable, which could be used to control the quality of L.barbarum fruit.

Development and validation of RP-HPLC method for quantification of repaglinide in mPEG-PCL polymeric nanoparticles: QbD-driven optimization, force degradation study, and assessment of in vitro release mathematic modeling

Repaglinide (REP) an insulinotropic agent used in the treatment of type-2 diabetes. It belongs to meglitinides, which act by blocking the ATP sensitive potassium channels and stimulates the insulin release. REP is the first insulin secretagogue used to target postprandial hyperglycemia. In this study, a rapid, sensitive, and reproducible RP-HPLC method has been developed and validated using an analytical quality-by-design approach. Initially, the Ishikawa fishbone diagram provides the basis of variation in critical analytical attributes with various inputs. Additionally, Taguchi design was selected to screen the critical method parameters affecting method development. Further, systemic optimization of the RP-HPLC method was determined by using Box-Behnken design. The chromatography separation was achieved by acetonitrile and phosphate buffer (60:40) with isocratic flow system on waters Nova-pack C18 column (3.9 × 150 mm, 4 μm) with 0.8 mL/min flow rate and the developed method was validated as per ICH guidelines. Moreover, the force degradation studies were also performed under different conditions (acidic, basic, oxidation and photolytic) to understand the degradation pathways and products. Furthermore, an amphiphilic di-block biodegradable polymer, i.e., polyethylene glycol-polycaprolactone (mPEG-PCL) was synthesized with different molecular weights to encapsulate REP and understand the release kinetics with mathematical modeling. In addition, the validated RP-HPLC method was effectively utilized to determine percent entrapment efficiency and loading efficiency of REP loaded nanoparticles. The developed method would also be applicable to quantify the REP from the biological matrix.

Analysis of Sterol Glucosides in Momordica charantia L. Extracts and Nutraceutical Products

Sterol glucosides were biosynthesised in Momordica charantia L. and used as markers for the standardization of M. charantia extracts. The sterol glucoside, charantin, used as a marker consisted of equal amounts of two sterol glucosides, namely, 5, 25-stigmastadienol glucoside (1) and β-sitosterol glucoside (2). Most quantitation methods either mixed up both isomers, namely (1) and stigmasterol glucoside (3) or both the sterol glucosides (1) and (2) were not separated in the quantitation methods. The labelling of individual sterol glucosides needs to be clearly stated in nutraceutical products. This study aimed to resolve the separation of the commonly mixed-up sterol glucosides and further validate a high-performance liquid chromatography-photodiode array detector (HPLC-PDA) method for the quantification of individual sterol glucosides in M. charantia. The HPLC-PDA instrument was used for method development as it is a universal instrument available in most nutraceutical companies. Sterol glucosides (1)-(3) were separated with a Zorbax SB-C18 column and an isocratic HPLC mobile phase system of 88% methanol in deionized water. The wavelength of the PDA detector was set at 200 to 500 nm with a linearity range of 90 to 300 µg/mL and a good correlation coefficient of r2 > 0.99. The validated method was applied to fresh fruits and nutraceutical products. The sterol glucoside (1) is the major constituent in charantin. Hybrid fruits biosynthesised higher content of sterol glucosides compared to non-hybrid fruits. The content of (1)-(3) in the final nutraceutical products fluctuates and dependent on the source of raw material. Thus, standardization of extracts is essential in nutraceutical production to ensure uniform content of secondary metabolites and reproducible therapeutic effect.

Determination of Bergenin in Different Parts of Bergenia ciliata using a Validated RP-HPLC Method

Bergenia ciliata (Family: Saxifragaceae) is a folklore remedy for the treatment of various ailments in Asian countries. Bergenin (1) has been isolated as an active constituent in many studies, however, the amount of bergenin has not been determined in all parts of the plant. A simple RP-HPLC method was developed to determine the amount of bergenin in methanol extracts of leaves, rhizomes and roots of the plant. Separation was achieved on an Agilent Eclipse XDB-C18 column maintained at 25 ℃ using isocratic solvent system (water: methanol: acetic acid; 62.5:37:0.5 v/v/v) adjusted at pH 2 0 at a flow rate of 1.0 mL/min. and detected at 275 nm. Correlation coefficient (0.9952) showed linearity of concentration (5-200 μg/mL) and response. The values of LOD (0.00947 μg/mL) and LOQ (0.02869 μg/mL) indicated that method was sensitive. The recovery of bergenin was 99.99-100% indicating accuracy of method. The methanol extract of rhizomes contained higher amount of bergenin (19.4%) than roots (9.2%) and leaves (6.9%). It is concluded that methanol extract of rhizomes is a better source of bergenin than other parts of the plant. The findings are useful for standardization of bergenin containing extracts and herbal preparations.

A Simultaneous, Validated RP-HPLC Method for Determination of Eight Cephalosporins in Pharmaceutical Formulations.

A reversed phase high performance liquid chromatographic method with isocratic solvent system has been developed and validated for the simultaneous determination of eight of cephalosporins antibiotics (Cefepime Hydrochloride, Ceftazidime, Ceftiofur Sodium, Cefotaxime Sodium, Ceftriaxone Sodium, Cefoperazone Sodium, Cephradine and Cefazolin Sodium) in pharmaceutical formulations with run time of 35 min. The best separation was obtained by using a 250 mm × 4.6 mm i.d, 5.0 μm particle size C8 reversed phase Agilent column and 0.1 M ammonium acetate buffer (pH 5.6): Acetonitril, 95:5 (v/v) as mobile phase at a flow rate of 0.8 mL/min. UV detection was conducted at 250 nm and column temperature at 30° C. The method linearity achieved over the concentration range of 0.5-50 μg/ mL with correlation coefficient (r2= 0.9999) for each studied cephalosporins. The developed method achieved lower limits of detection (0.018 µg/mL: 0.03 µg/mL) and lower limits of quantification (0.056 µg/mL: 0.09 µg/mL). The suggested method is highly sensitive, accurate, precise, and could be used for quality control assay and routine analysis for this group of cephalosporins in pharmaceutical formulations.

Exploiting column chemistry for chromatographic separation and quantification of caffeoylquinic acids in Gynura procumbens

AbstractA simple and sensitive high-performance liquid chromatography-ultraviolet (HPLC-UV) method was developed by exploiting the benefits of phenyl-hexyl column for the simultaneous determination of mono- and di-caffeoylquinic acids in Gynura procumbens plant samples. An optimal chromatographic separation was achieved by using a mobile phase of acetonitrile: 0.25% acetic acid in water (12.5:78.5, v/v) and detection at 330 nm. The limits of detection (LOD) and quantification (LOQ) for the six caffeoylquinic acid standards were in the range of 0.078–0.653 and 0.259–1.795 μg/mL, respectively. The accuracies of the developed method were in the range of 96.84–103.08%, while the corresponding precisions were between 0 and 2.94% for both within-day and between-day analyses, indicating that the method is repeatable and reliable. The mean recoveries were between 87.08 and 117.83%. The method was successfully applied for quantification of caffeoylquinic acids in G. procumbens plant samples. This is the first study on di-caffeoylquinic acids quantification in G. procumbens. Leaves samples contained higher amount of the caffeoylquinic acids compared to stem samples. Of the compounds, 3,5-dicaffeoylquinic acid was found to be the major compound in almost all G. procumbens samples. The method has advantages such as sensitive ultraviolet (UV) detection, short run time with simple isocratic elution system compared to other methods which involved the use of costly instruments, laborious procedures with long run time and complex gradient system. This method can be further extended for routine quality control and analysis of plants or herbal products containing the caffeoylquinic acids.

Biogenic Amines as Freshness Indicator in Halal and Non-Halal Slaughtered Chicken Meat Using Chromatographic Approach

Biogenic amines are naturally occurring organic bases produced by bacterial decarboxylation of amino acids that have been associated with harmful toxicology effects to humans. The main objective of this work is to investigate the possible role of biogenic amines (BAs) as indicators of spoilage in fresh chicken meat stored at 4°C for 15 days. A reversed-phase high-performance liquid chromatographic method with isocratic elution system is used for the quantification of four biogenic amines (putrescine, histamine, tyramine, cadaverine and spermine as well as spermidine) in chicken meat. Amines were extracted with 5% of trichloroacetic acid (TCA) and derivatised using dansyl chloride. The variation storage time differentiated the chicken meat on the microbiological characteristics. The results obtained shows that histamine, spermidine, tyramine, cadaverine, and putrescine increased slowly while spermine decreased for both chicken breast in halal and non-halal chicken meat. Thus, this BAs could be used as a spoilage index of fresh chicken meat.

Determination and Pharmacokinetics of Omeprazole Enantiomers in Human Plasma and Oral Fluid Utilizing Microextraction by Packed Sorbent and Liquid Chromatography-Tandem Mass Spectrometry.

In the present work, the determination of omeprazole (OME) enantiomers in oral fluid and plasma samples was carried out utilizing microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry. A chiral column with cellulose-SB phase was used for the first time for enantiomeric separation of OME with an isocratic elution system using 0.2% ammonium hydroxide in hexane-ethanol mixture (70 : 30, v/v) as the mobile phase. OME enantiomers were determined utilizing a triple quadrupole tandem mass spectrometer in positive ion mode (ESI+) monitoring mass transitions: m/z 346.3 ⟶ 198.0 for OME and m/z 369.98 ⟶ 252.0 for internal standard. The limits of detection and quantification of the present method for both enantiomers were 0.1 and 0.4 ng/mL, respectively. The method validation provided good accuracy and precision. The matrix effect factor was less than 5%, and no interfering peaks were observed. The interday precision values ranged from 2.2 to 7.5 (%RSD), and the accuracy of determinations varied from −9.9% to 8.3%. In addition, the pharmacokinetics (PK) of omeprazole enantiomers in healthy subjects after a single oral dose was investigated. (S)-Enantiomers showed higher levels than (R)-enantiomers throughout 24 h. It was found that the mean maximum concentrations of (R)- and (S)-omeprazole in plasma samples were about two times higher than in oral fluid.