Phase LC Method Research Articles

SIMULTANEOUS QUANTIFICATION OF MINOXIDIL AND FINASTERIDE IN BULK AND PHARMACEUTICAL DOSAGE FORM BY RP-HPLC METHOD

A strategic specific and sensitive quantitative analysis of Minoxidil and Finasteride has been developed by using HPLC with reliable, precise, and accurate result in bulk and marketed formulation. In this method Phenomenex C 18 (250 mm × 4.6 mm, 5 μm) column was used as stationary phase and a composition of Methanol: Water (85:15 v/v) was used as mobile phase. An isocratic elution programming has been done at a flow rate of 1 mL min -1 . The eluted analytes show appreciable absorbance at 223 nm. The proposed RP-LC method was validated according to ICH guidelines. The retention time of Minoxidil and Finasteride was found to be 3.15 min and 4.36 min respectively. The method was found to be linear over a range of 6 – 54 µg mL -1 for Minoxidil and 0.2-1.8 µg mL -1 for Finasteride. The percentage recovery was found to be 99.88-100.85 % for Minoxidil and 99.99-100.33 % for Finasteride. The proposed reverse phase LC method has potential qualitative as well as quantitative applications for simultaneous estimation of Minoxidil and Finasteride in bulk and pharmaceutical dosage form.

Development and validation of LC methods for the separation of misoprostol related substances and diastereoisomers

Misoprostol is a synthetic prostaglandin E1 analogue which is mainly used for prevention and treatment of gastric ulcers, but also for abortion due to its labour inducing effect. Misoprostol exists as a mixture of diastereoisomers (1:1) and has several related impurities owing to its instability at higher temperatures and moisture. A simple and robust reversed phase liquid chromatographic (RPLC) method is described for the separation of the related substances and a normal phase (NP) LC method for the separation of misoprostol diastereoisomers. The RPLC method was performed using an Ascentis Express C18 (150mm×4.6mm, 5μm) column kept at 35°C. The mobile phase was a gradient mixture of mobile phase A (ACN–H2O–MeOH, 28:69:3 v/v/v) and mobile phase B (ACN–H2O–MeOH, 47:50:3 v/v/v) eluted at a flow rate of 1.5mL/min. UV detection was performed at 200nm. The NPLC method was undertaken by using an XBridge bare silica (150mm×2.1mm, 3.5μm) column at 35°C. The mobile phase contained 1-propanol–heptane–TFA (4:96:0.1%, v/v/v), pumped at a flow rate of 0.5mL/min. UV detection was performed at 205nm. This LC method can properly separate the two diastereoisomers (Rs>2) within an analysis time of less than 20min. Both methods were validated according to the ICH guidelines. Furthermore, these new LC methods have been successfully applied for purity control and diastereoisomers ratio determination of misoprostol bulk drug, tablets and dispersion.

A Novel Stability Indicating HPLC Assay Method for Simultaneous Estimation of Clopidogrel and Aspirin in Tablet dosage form by Using Core shell Technology column

A novel, rapid and a stability-indicating reverse phase LC method has been developed and validated for the simultaneous estimation of Clopidogrel and Aspirin in tablet dosage form. The chromatographic separation was achieved on a novel core shell technology phenyl hexyl stationary phase of particle size 2.6μ. The method employed a linear gradient elution and the detection wavelength was set at 220nm. The proposed method was extensively validated as per ICH guidelines. The specificity of the method was proved by performing forced degradation studies. Regression analysis shows r value (correlation coefficient) of greater than 0.999 for individual active drug substances. Accuracy was proved in the range of 50% to 150% of working range.

Analysis of Cocoa Flavanols and Procyanidins (DP 1–10) in Cocoa-Containing Ingredients and Products by Rapid Resolution Liquid Chromatography: Single-Laboratory Validation

Recently, a multilaboratory validation (MLV) of AOAC Official Method 2012.24 for the determination of cocoa flavanols and procyanidins (CF-CP) in cocoa-based ingredients and products determined that the method was robust, reliable, and transferrable. Due to the complexity of the CF-CP molecules, this method required a run time exceeding 1 h to achieve acceptable separations. To address this issue, a rapid resolution normal phase LC method was developed, and a single-laboratory validation (SLV) study conducted. Flavanols and procyanidins with a degree of polymerization (DP) up to 10 were eluted in 15 min using a binary gradient applied to a diol stationary phase, detected using fluorescence detection, and reported as a total sum of DP 1-10. Quantification was achieved using (-)-epicatechin-based relative response factors for DP 2-10. Spike recovery samples and seven different types of cocoa-based samples were analyzed to evaluate the accuracy, precision, LOD, LOQ, and linearity of the method. The within-day precision of the reported content for the samples was 1.15-5.08%, and overall precision was 3.97-13.61%. Spike-recovery experiments demonstrated recoveries of over 98%. The results of this SLV were compared to those previously obtained in the MLV and found to be consistent. The translation to rapid resolution LC allowed for an 80% reduction in analysis time and solvent usage, while retaining the accuracy and reliability of the original method. The savings in both cost and time of this rapid method make it well-suited for routine laboratory use.

A Validated Normal Phase LC Method for Enantiomeric Separation of Rasagiline Mesylate and Its (S)‐Enantiomer on Cellulose Derivative‐Based Chiral Stationary Phase

A simple, sensitive, and robust normal-phase isocratic HPLC-UV method was developed and validated for the enantiomeric separation of rasagiline mesylate and its (S)-enantiomer. The rasagiline and its (S)-enantiomer were resolved on a Chiralcel-OJ-H (4-methylbenzoate cellulose coated on silica) column using a mobile phase consisting of n-hexane:isopropyl alcohol:ethanol:diethyl amine (96:2:2:0.01) at a flow rate of 1.0 ml/min. The column temperature was maintained at 27 °C and elution was monitored at 215 nm. The resolution (Rs ) between the enantiomers was found to be more than 2.0. The limit of detection and the limit of quantification of the (S)-enantiomer were found to be 0.35 and 1.05 µg/ml, respectively. The developed method was validated as per ICH guidelines with respect to linearity, limit of detection and quantification, accuracy, precision, and robustness-and satisfactory results were obtained. The sample solution and mobile phase were found to be stable up to 48 h. The method is useful for routine evaluation of the quality of rasagiline mesylate in bulk drug-manufacturing units.

Liquid Chromatographic Method for the Analysis of Brimonidine in Ophthalmic Formulations

A reverse phase LC method was developed for the determination of Brimonidine in eye drops. Chromatography was carried on an Inertsil ODS 3V column (C18) using a mixture of Octane 1- sulfonic acid sodium salt (0.02M) (pH 3.5 ± 0.05) and acetonitrile (64:36 v/v) as mobile phase at a flow rate of 1 mL/min with UV detection at 254 nm. The drug was eluted at 4.636 min. The detector response was linear in the concentration range of 0.4–72 μg/mL. The limit of detection and limit of quantification were found to be 0.0561 and 0.1848 μg/mL respectively. The proposed method was validated as per the ICH guidelines and can be applied for the routine analysis of Brimonidine in eye drops.

STABILITY STUDY OF CAPECITABINE ACTIVE PHARMACEUTICAL INGREDIENT IN BULK DRUG AND PHARMACEUTICAL FORMULATION

A simple, precise, and accurate gradient reverse phase-LC method was developed for quantitative determination of capecitabine (CPT) drug sample and drug products in bulk samples and pharmaceutical dosage forms. Accelerated tests for stability evaluation were performed at 40°C ± 2°C and 75 ± 5% relative humidity (RH), according to the current official guidelines. The samples were kept in a climatic chamber for 6 mo in the aforementioned conditions. The samples were withdrawn from the climatic chamber and analyzed periodically (0, 3, and 6 mo) by HPLC on an Eclipse XDB-C18 column (250 × 4.6 mm i.d. particle size is 5 µm), using a mobile phase of 0.02 M ammonium formate containing formic acid to maintain pH at 4.0-acetonitrile with gradient, at a flow rate of 1.0 mL min−1. The UV detector was operated at 240 nm while column temperature was maintained at 40°C. The unknown impurity at relative retention time (RRT) of 0.26 min ranged from 0.02 to 1.90% on an area-percentage basis and has been observed in reverse phase-LC of CPT drug substance and drug product in accelerated test at two time points, initial (0 mo) and 6 mo. Chemically, the impurity was identified as 4-amino-1-(3,4-dihydroxy-5-methyltetrahydrofuran-2-yl)-5-fluoro-pyrimidin-2(1H)-one. Utility of the developed method was examined by analyzing the tablets containing CPT. The results of analysis were supported by statistical parameters.

English

A novel stability-indicating LC assay method was developed and validated for quantitative determination of Rifabutin in bulk drugs and in pharmaceutical dosage form in the presence of degradation products generated from forced degradation studies. An isocratic, reversed phase LC method was developed to separate the drug from the degradation products, using an Ace5-C18 (250 x 4.6 mm, 5 µm) column, and 50 mM ammonium acetate (pH-4 by acetic acid) and acetonitrile (50:50v/v) as a mobile phase. The detection was carried out at the wavelength of 275 nm. The Rifabutin was subjected to stress conditions of hydrolysis (acid, base), oxidation, photolysis and thermal degradation. Degradation was observed for Rifabutin hydrolysis (acid, base), oxidation and photolysis conditions attempted. There is no degradation in thermal condition. The degradation products were well resolved from the main peak. The percentage recovery of Rifabutin ranged from (99.42 to 100.27%) in pharmaceutical dosage form. The developed method was validated with respect to linearity, accuracy (recovery), precision, specificity and robustness. The forced degradation studies prove the stability-indicating power of the method.   Key words: Rifabutin, column liquid chromatography, stability indicating method, validation.

A Sensitive and Simple HPLC-UV Method for Trace Level Quantification of Ethyl p-Toluenesulfonate and Methyl p-Toluenesulfonate, Two Potential Genotoxins in Active Pharmaceutical Ingredients

A sensitive and simple HPLC/UV method has been developed and validated for the determination of two potential genotoxic impurities, namely methyl p-toluenesulfonate (MPTS) and ethyl p-toluenesulfonate (EPTS) at trace levels in Pemetrexed sodium API. Applying the concept of threshold of toxicological concern (TTC), a limit of 3 ppm each for both genotoxins was calculated based on the maximum daily dose of API. A reversed phase LC method using UV detection was developed and validated. The method was found to be specific and selective for the application. The limit of detection (LOD) and limit of quantitation (LOQ) for both MPTS and EPTS was found to be 0.15 ppm (0.009 μg mL−1) and 0.5 ppm (0.03 μg mL−1), respectively, with respect to sample concentration. The calibration curves of MPTS and EPTS were linear over the concentration range from LOQ to 6 μg/mL. The method was found to be specific, precise, linear and accurate and has been successfully applied to determine the two genotoxins in commercial batches of the API.

LC Determination of Clindamycin Phosphate from Chitosan Microspheres

A simple, rapid and precise reverse phase LC method was adopted, modified and validated for the determination of clindamycin phosphate from chitosan microspheres prepared by spray drying method. Separation was performed using ACE5 C18 reversed phase column (150 mm × 4.6 mm, 5 μm) with acetonitrile:phosphate buffer at pH 2.5 (25:75 v/v) as mobile phase. The limit of detection was 46.43 × 10−3 μg mL−1, with UV detection at 210 nm. No interference from chitosan and other excipients was observed. Therefore an incorporation efficiency of microspheres could be determined accurately and specifically.

An Improved Ion-Pair Reversed Phase LC Method for Analysis of Major Impurities of Phosphorothioate Oligonucleotide Cantide

An improved ion-pair reversed phase LC (IP-RP-LC) method was developed using triethylammonium/hexafluoroisopropanol (TEA/HFIP) buffer as the mobile phase as an alternative to capillary gel electrophoresis (CGE) and ion-exchange chromatography (IEC) for routine quality control of the synthetic 20-mer phosphorothioate oligonucleotide (PS-ODN) Cantide. The most commonly observed impurities included an oligomer with a deletion at the 5′-end (5′n-1) and a monophosphodiester (P=S/O). The method described here was sufficiently selective to simultaneously separate and identify these impurities. To the best of our knowledge, this is the first report on the separation of P=S/O analogs from PS-ODN using IP-RP-LC. Relatively high TEA concentrations and higher pH values were recommended. The separation performance was maintained even in the presence of multiple P=S/O fragments containing different PO residues. The method was successfully applied to the analysis of failure sequences of authentic crude Cantide as well as the purified product. In addition to 5′n-1 and P=S/O analogs, some minor impurities such as 3′n-1 oligomers were also partially resolved.

Separation of Tocopheryl Acetate Isomers on Porous Graphitic Carbon

Vitamin E is a collective term for tocopherols and tocotrienols that includes isomers differing in the number and position of methyl substituents. An LC impurity method was required to determine the purity of RRR-α-tocopheryl acetate, especially with regard to the amounts of the β- and γ-isomers which have one fewer methyl substituents. Using the Hypercarb porous graphitic carbon column, a normal phase LC method was developed that separates α-, β-, γ-, and δ-tocopheryl acetates using a mobile phase of 25:85 (v/v) THF:hexane. The area response with detection at 205 nm is linear for column loadings of 0.006–10 μg of α-tocopheryl acetate. It was also noted that SRR-α-tocopheryl acetate is partially resolved from RRR-α-tocopheryl acetate under these conditions.

Metabolomic analysis via reversed-phase ion-pairing liquid chromatography coupled to a stand alone orbitrap mass spectrometer.

We present a liquid chromatography-mass spectrometry (LC-MS) method that capitalizes on the mass-resolving power of the orbitrap to enable sensitive and specific measurement of known and unanticipated metabolites in parallel, with a focus on water-soluble species involved in core metabolism. The reversed phase LC method, with a cycle time 25 min, involves a water-methanol gradient on a C18 column with tributylamine as the ion pairing agent. The MS portion involves full scans from 85 to 1000 m/z at 1 Hz and 100,000 resolution in negative ion mode on a stand alone orbitrap ("Exactive"). The median limit of detection, across 80 metabolite standards, was 5 ng/mL with the linear range typically >or=100-fold. For both standards and a cellular extract from Saccharomyces cerevisiae (Baker's yeast), the median inter-run relative standard deviation in peak intensity was 8%. In yeast exact, we detected 137 known compounds, whose (13)C-labeling patterns could also be tracked to probe metabolic flux. In yeast engineered to lack a gene of unknown function (YKL215C), we observed accumulation of an ion of m/z 128.0351, which we subsequently confirmed to be oxoproline, resulting in annotation of YKL215C as an oxoprolinase. These examples demonstrate the suitability of the present method for quantitative metabolomics, fluxomics, and discovery metabolite profiling.

A validated stability-indicating normal phase LC method for clopidogrel bisulfate and its impurities in bulk drug and pharmaceutical dosage form

A novel stability-indicating normal phase liquid chromatographic (NP-LC) method was developed for the determination of purity of clopidogrel drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. This method is capable of separating all the related substances of clopidogrel along with the chiral impurities. This method can be also be used for the estimation of assay of clopidogrel in drug substance as well as in drug product. The method was developed using Chiralcel OJ-H (250 mm × 4.6 mm, 5 μm) column. n-Hexane, ethanol and diethyl amine in 95:5:0.05 (v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 240 nm. Clopidogrel bisulfate was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantification, precision, linearity, accuracy, robustness and system suitability.

A Simple and Rapid Stability Indicating LC Determination of Ciprofloxacin Hydrochloride as a Bulk Drug and from Formulations

The present research work discusses the development of a stability indicating reversed phase LC method for determination of ciprofloxacin hydrochloride as a bulk drug and from formulations. The mobile phase selected was water-acetonitrile-triethylamine 75:25:0.1 (v/v/v) adjusted to pH 4.0 with o-phosphoric acid. The calibration curve of the drug was linear in the range 0.25–15 μg mL−1. The method was accurate and precise with limits of detection and quantitation of 8.01 and 26.7 ng, respectively. Mean percent recovery was 100.71%. The method was used for analysis of ciprofloxacin hydrochloride from pharmaceutical formulations in the presence of its degradation products and commonly used excipients.

LC Evaluation of In Vitro Release of AZT from Microemulsions

A reversed phase LC method was developed and validated to analyze the in vitro release of AZT from microemulsions. A mobile phase of acetonitrile:water (15:85) was used. The method validation showed good selectivity and linearity (r = 0.9993) for sample concentrations ranging from 0.6 to 100.0 μg mL−1. The RSD values (0.7–4.3%) and percentage recovery (88.1–109.8%) were within acceptable limits. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.012 and 0.041 μg mL−1. Quantitative analysis of the values obtained in the drug release assay indicates that the microemulsions used promote sustained release of AZT, which follows a Fickian diffusion mechanism.

An LC Method for Quantification of 2,3-Dichlorobenzoyl Cyanide and Its Related Regio Isomers

A simple, sensitive and selective gradient reversed phase LC method has been developed for separation and determination of 2,3-dichlorobenzoyl cyanide and its regio isomers which is an intermediate of lamotrigine pure form. The separation was achieved on a reversed phase C-18 column using 0.01 M ammonium acetate buffer at pH 5.5 and methanol (50:50 v/v) mixture as solution A and methanol, water mixture (90:10 v/v) as solution B in a gradient elution at a flow rate of 1.5 mL min−1 with UV detection at 215 nm. The method is found to be selective, precise, linear, accurate and also robust. It was not only used for quality assurance, but also monitoring the synthetic reactions involved in the process development of Lamotrigine. The LC method is found to be simple, rapid, specific and reliable for the determination of unreacted levels of raw materials and isomers in reaction mixtures and finished product Lamotrigine. The method was fully validated as per ICH guidelines and results from validation confirm that the method is highly suitable for its intended purpose.

Stability-Indicating LC Method for the Determination of Olmesartan in Bulk Drug and in Pharmaceutical Dosage Form

A novel stability-indicating LC assay method was developed and validated for quantitative determination of olmesartan in bulk drugs and in pharmaceutical dosage form in the presence of degradation products generated from forced degradation studies. An isocratic, reversed phase LC method was developed to separate the drug from the degradation products, using an Ace5-C18 (250 mm × 4.6 mm, 5 μm) column, and 50 mM ammonium acetate (pH-5.5 by acetic acid) and acetonitrile (70:30 v/v) as a mobile phase. The detection was carried out at the wavelength of 235 nm. The olmesartan was subjected to stress conditions of hydrolysis (acid, base), oxidation, photolysis and thermal degradation. Degradation was observed for olmesartan in acid, base and in 30% H2O2 conditions. The drug was found to be stable in the other stress conditions attempted. The degradation products were well resolved from the main peak. The percentage recovery of olmesartan ranged from (99.89 to 100.95%) in pharmaceutical dosage form. The developed method was validated with respect to linearity, accuracy (recovery), precision, specificity and robustness. The forced degradation studies prove the stability-indicating power of the method.

Validation of a Stability Indicating Reversed Phase LC Method for the Determination of Fluticasone Propionate in Pharmaceutical Formulations

A reversed phase liquid chromatography (RP-LC) method was validated for the determination of fluticasone propionate (FP) in nasal sprays. The LC method was carried out on a Shim-pack CLC-ODS column (150 mm × 4.6 mm I.D.), maintained at 35°C. The mobile phase consisted of acetonitrile/methanol/phosphate buffer (0.01 M, pH 4.0) (35:35:30, v/v/v), run at a flow rate of 1.0 mL/min and using photodiode array (PDA) detection at 240 nm. The chromatographic separation was obtained with retention time of 6.1 min, and was linear in the range of 0.05–150 µg/mL (r 2 = 0.9999). The specificity and stability indicating capability of the method were proven through degradation studies, which also showed that there was no interference of the excipients. The accuracy was 99.36% with bias lower than 1.12%. The limits of detection and quantitation were 0.03 and 0.05 µg/mL, respectively. Moreover, method validation demonstrated acceptable results for precision and robustness. The proposed method was applied for the analysis of the nasal sprays and cream pharmaceutical formulations, contributing to improve the quality control and to assure the therapeutic efficacy.

Stability-Indicating LC Determination of Nitazoxanide in Bulk Drug and in Pharmaceutical Dosage Form

A novel stability-indicating high-performance liquid chromatographic assay method was developed and validated for quantitative determination of nitazoxanide in bulk drugs and in pharmaceutical dosage form in the presence of degradation products generated from forced decomposition studies. An isocratic, reversed phase LC method was developed to separate the drug from the degradation products, using an Ace5- C18 (250 mm × 4.6 mm, 5 μm) column, and 50 mM ammonium acetate (pH 5.5 by acetic acid) and acetonitrile (55:45 v/v) as a mobile phase. The detection was carried out at a wavelength of 240 nm. The nitazoxanide was subjected to stress conditions of hydrolysis (acid, base), oxidation, photolysis and thermal degradation. Degradation was observed for nitazoxanide in base, acid and in 30% H2O2 conditions. The drug was found to be stable in the other stress conditions attempted. The degradation products were well resolved from the main peak. The percentage recovery of nitazoxanide was from (100.55 to 101.25%) in the pharmaceutical dosage form. The developed method was validated with respect to linearity, accuracy (recovery), precision, system suitability, specificity and robustness. The forced degradation studies prove the stability indicating power of the method.