A Rapid Microscale Method for the Determination of Partition Coefficients by HPLC

Abstract

A rapid, reliable and simple microscale method for the determination of octanol-water partition coefficients has been developed and evaluated. Rapid solute partitioning and facile octanol-water phase separation is accomplished in a commercially available mixer-separator device. The relative concentration of solute in each phase is then measured directly by computer-based reverse phase HPLC. The procedure requires only 10 μg of sample, which need not be pure, and uses 1 ml or less of both n-octanol and pH 7.0 phosphate buffer. Log P values of 26 compounds, mainly nucleoside analogues with anti-HIV and antitumor activity, have been determined in the range 0.7 to -2.4 with a precision better than ±0.04 log units. For compounds with literature data available, measured log P values are in good agreement (better than ±0.2 log units) with those values obtained by traditional “shake-flask” methodology. The described method is applicable to both single compound analysis and simultaneous multiple compound determinations through use of isocratic or gradient HPLC techniques.     

Development and Validation of a Reversed-Phase HPLC Method for the Determination of Deflazacort in Pharmaceutical Dosage Forms

A reversed-phase high-performance liquid chromatographic method has been developed and validated for quantitative determination of deflazacort in tablets and in compounded capsules. Isocratic chromatography was performed on a C₁₈ column with acetonitrile–water 80:20 (v/v) as mobile phase at a flow rate of 1.0 mL min^?1. UV detection was at 240 nm. The linearity of the method was good (r > 0.999), as also were intra-day and inter-day precision (RSD <2%) and accuracy (recovery >98%). The method was also validated for specificity and robustness. The results showed the proposed method is suitable for its intended use.     

Determination of Ebselen by HPLC: Validation and Application of the Method

Ebselen is an organo-selenium, highly hydrophobic compound that exhibits glutathion peroxidase-like activity. It is now in phase III trials in Japan for investigating its effect on ischemic stroke. We have developed an HPLC method for the determination of Ebselen at ambient temperature and applied it to a patented tablet formulation. The mobile phase composition, detection wavelength and chromatographic conditions were optimized. The optimum conditions are a Waters, C₁₈, (25 cm × 4.6 mm, 5 μm) column, 1% acetic acid: methanol: propanol (40:50:10) (ν/ν) as the mobile phase at a flow rate of 0.7 mL min^?1 and detection at 254 nm (internal standard: benzanilide). The method was validated and calibration curves were constructed depended on the ratios of Ebselen to benzanilide peak areas. The concentration range for Ebselen was 0.82–11.71 μg mL^?1, y=0.4021x + 0.0145 (r²=0.9993). Limit of quantification (LOQ) and limit of detection (LOD) were determined as 1.49 μg mL^?1 and 0.45 μg mL^?1 respectively, based on the blank signal and standard deviation of the peak areas of the minimum concentration of Ebselen. Recovery of Ebselen was found to be 98.70 ± 0.75% for 30 mg of tablet powder and 97.43 ± 0.78% for the 30 mg tablet form. The RSD was found to be 1.27% for 10 replicate injections of 50 μL. The ruggedness of the method was investigated by carrying out the same procedure on different days. There was no significant difference between 2 and 7 days time periods. The HPLC method is compared to a spectrophotometric method.     

Development and Validation of an HPLC–UV Method for the Determination of Insulin in Rat Plasma: Application to Pharmacokinetic Study

A simple, sensitive high performance liquid chromatographic method with UV detection was developed and validated for determination of insulin in rat plasma, using methyl paraben as an internal standard. Insulin was extracted from plasma by a liquid–liquid extraction with a mixture of dichloromethane and n-hexane (1:1, v/v) followed by an acidic back extraction. Chromatographic separation was achieved isocratically with a Phenomenex® C₁₈ analytical column (150 × 4.6 mm ID, 5 μm) at ambient room temperature. The calibration curves were linear within a concentration range of 0.7–8.4 μg mL^?1 (r ² = 0.9994). The inter-day and intra-day accuracy and precision were ≤3.33 and ≤5.55%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.35 and 0.7 μg mL^?1. The average recovery was 87.86% for insulin and 83.52% for methyl paraben. Insulin containing plasma samples were stable at ?20 °C for 7 days. Validated HPLC method was successfully applied to a pharmacokinetic study of insulin in streptozotocin induced diabetic rats.     

Development and Validation of an HPLC Method for Determination of Ceftiofur Sodium

An isocratic high-performance liquid chromatographic method has been developed for assay of ceftiofur sodium in drug substance and in sterile powder for injection. Chromatography was performed on a 250 mm × 4.6 mm, 5 μm particle, C₁₈ column with a 78:22 (v/v) mixture of 0.02 m disodium hydrogen phosphate buffer (pH adjusted to 6.0 with 85% orthophosphoric acid) and acetonitrile as mobile phase, at a flow rate of 1.0 mL min⁻¹. The separation was monitored by UV detection at 292 nm. Validation of the method for linearity and range, intra- and inter-day precision, accuracy, specificity, recovery, robustness, and limits of quantification and detection yielded good results. The calibration plot was linear from 20.0–120.0 μg mL⁻¹ and the correlation coefficient was 0.9999. It was shown that ceftiofur was degraded under acidic, alkaline, oxidative, and photolytic conditions. The method was found to be stability-indicating and could be used for routine analysis of ceftiofur sodium for injection.     

Determination of Octanol–Water Partition Coefficients,Water Solubility and Vapour Pressures of Alkyl-lead Compounds

Physico-chemical properties of alkyl-lead compounds, namely aqueous solubility, octanol–water partition coefficient ( K _ow), vapour pressure and Henry's Law constant, have been determined. Vapour pressures of trialkyl-lead salts at different temperatures were measured by a gas-saturation technique in which air was passed slowly through a glass column packed with pure solid alkyl-lead compounds. K _ow of tetra-alkyl-lead (TAL) and trialkyl-lead (TriAL) were determined under different salinity and pH conditions, and the latter were related to the species (R₃Pb⁺, R₃PbOH⁰ or R₃PbCl⁰) dominating under a particular set of conditions. Regression calculations incorporating melting point corrections relate water solubility to K _ow, and provide a means of estimating either parameter for a wider range of compounds.     

Development and Validation of a Stability-Indicating LC Method for Determination of Bexarotene in Softgel Dosage Formulation

This study focuses on a novel liquid chromatographic approach that has been developed and approved for the quantitative determination of bexarotene (BXT), its potential impurities in drug substances and drug products. Chromatographic separation was developed on a Symmetry C₈ (150 × 4.6) mm 5-µm column with a mobile phase containing an isocratic mixture of acetonitrile:DI water:glacial acetic acid (650:350:7.5) v/v/v at a flow rate of 1.2 mL min^?1, and quantitation was carried out using ultraviolet detection at 262 nm for BXT and 290 nm for BHA with a column temperature of 35 °C. The resolution among butylated hydroxyanisole (BHA), BXT and its process-related impurity-A was found to be greater than 5. Regression analysis confers an R value (correlation coefficient) higher than 0.998 for BHA, BXT and impurity-A. The detection level for BXT impurities was found at a level below 0.03% (0.18 µg mL^?1). The inter- and intra-day precisions for BHA, BXT and impurities were evaluated and found to have a %RSD of less than 3.0.     

Determination of Carbamazepine in Parenteral Nanoemulsions: Development and Validation of an HPLC Method

A high performance liquid chromatographic method was developed and validated for the quantitative determination of carbamazepine in intravenous nanoemulsions. The method validation yielded good results with respect to linearity, specificity, precision and accuracy. The method was carried out on a RP-18 column with a mobile phase composed of methanol–water (70:30 v/v) subjected to a gradient of acetonitrile after drug elution, and detection at 286 nm. The linearity in the range of 10.0–50.0 μg mL⁻¹ presented a determination coefficient (r ²) of 0.9996, calculated by least-squares regression; the RSD values for intra-day and inter-day precision for % recovered were <0.44 and <1.21%, respectively; and the recovery of carbamazepine from the sample matrix ranged from 94.3 to 104.9%.     

Development and Validation of a Stability Indicating HPLC Method for Determination of Granisetron

The aim of this study was to study the stress degradation of granisetron and analysis of the drug in the presence of its degradation products. Forced degradation studies were conducted on bulk sample using acidic, alkaline, oxidative, heat and photolytic conditions. Granisetron was relatively unstable under acidic, alkaline and oxidative conditions. Separation of granisetron and degradation products was achieved using a Nova‐Pak C₈ column and acetonitrile‐KH₂PO₄ 25 mM (75:25, v/v) as mobile phase with UV detection at 305 nm. The method was linear over the range of 0.2‐15 μg/mL granisetron (r² > 0.999). The within‐day and between‐day precision values were also in the range of 0.5‐4%. The proposed method was successfully applied for quantitative determination of granisetron in tablets and in vitro dissolution studies.     

Box–Behnken Design-Based Development and Validation of a Reverse-Phase HPLC Analytical Method for the Estimation of Paclitaxel in Cationic Liposomes

Chromatographia - Stability-indicating reverse-phase HPLC analytical method for the quantification of Paclitaxel (PTX) in the bulk and cationic liposomes was developed. The optimized method was...     

Development and Validation of Spectrophotometric Methods for the Determination of Cefetamet in Pharmaceutical Dosage Forms

Two simple and sensitive spectrophotometric methods for the determination of cefetamet in either pure form or in its pharmaceutical formulations were described. The method Ⅰ is based on the interaction of 3-methylbenzo[d]- thiazolin-2-one hydrazone （MBTH） with cefetamet in the presence of freshly prepared ferric chloride in a neutral medium. The resulting blue colored product has λmax at 628 nm. The method Ⅱ describes the reduction of ferric ion by the drug to ferrous ion followed by a complex formation reaction with 1,10-phenanthroline （1,10-phen） to form an orange red colored chromogen exhibiting 2max at 510 nm. The products are stable for more than 5 and 8 h respectively. Common excipients used as additives in pharmaceutical preparations do not interfere in the proposed methods. Both methods are highly reproducible and have been applied to a wide variety of pharmaceutical preparations and the results are comparable with those of official methods.     

Development and Validation of a Stability-Indicating UPLC Method for the Determination of Hexoprenaline in Injectable Dosage Form Using AQbD Principles

A novel and efficient stability-indicating, reverse phase ultra-performance liquid chromatographic (UPLC^®) analytical method was developed and validated for the determination of hexoprenaline in an injectable dosage form. The development of the method was performed using analytical quality by design (AQbD) principles, which are aligned with the future requirements from the regulatory agencies using AQbD principles. The method was developed by assessing the impact of ion pairing, the chromatographic column, pH and gradient elution. The development was achieved with a Waters Acquity HSS T3 (50 × 2.1 mm i.d., 1.8 µm) column at ambient temperature, using sodium dihydrogen phosphate 5 mM + octane-1-sulphonic acid sodium salt 10 mM buffer pH 3.0 (Solution A) and acetonitrile (Solution B) as mobile phases in gradient elution (t = 0 min, 5% B; t = 1 min, 5% B; t = 5 min, 50% B; t = 7 min, 5% B; t = 10 min, 5% B) at a flow rate of 0.5 mL/min and UV detection of 280 nm. The linearity was proven for hexoprenaline over a concentration range of 3.50–6.50 µg/mL (R² = 0.9998). Forced degradation studies were performed by subjecting the samples to hydrolytic (acid and base), oxidative, and thermal stress conditions. Standard solution stability was also performed. The proposed validated method was successfully used for the quantitative analysis of bulk, stability and injectable dosage form samples of the desired drug product. Using the AQbD principles, it is possible to generate methodologies with enhanced knowledge, which can eventually lead to a reduced regulatory risk, high quality data and lower operational costs.     

Development and Validation of High-Performance Thin-Layer Chromatographic Method for the Simultaneous Determination of Rifampicin,Isoniazid, and Pyrazinamide in a Fixed Dosage Combination Tablet

JPC – Journal of Planar Chromatography – Modern TLC -     

Stability-Indicating HPTLC Method for the Determination of Atorvastatin and Ezetimibe: Application to Pharmaceutical Dosage Forms

JPC – Journal of Planar Chromatography – Modern TLC -     

Development and Validation of an HPLC Method for Simultaneous Determination of Ibuprofen and 17 Related Compounds

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for determination of ibuprofen and 17 related compounds (chemical process impurities and degradation products) simultaneously. This method may be used for quality control of ibuprofen-containing substances. A number of chromatographic parameters (column, flow rate, temperature, wavelength, gradient elution, buffer solution, and pH) were evaluated. An Agilent ZORBAX Eclipse Plus C18 (250 × 4.6 mm, 5 μm particle size) column at 40 °C was selected on the basis of its separation efficiency and robustness. The column was eluted at 1.0 mL min^?1 with a gradient using 10 mM sodium phosphate buffer at pH 6.9 as mobile phase A and acetonitrile as mobile phase B. The ultraviolet detector was set at 214 nm. This method was validated to confirm its system suitability, specificity, linearity, precision, accuracy, sensitivity, robustness, and sample stability according to international conference on harmonization (ICH) guidelines. This method was applied to analyze seven batches of ibuprofen drug products from different manufacturers.     

Evaluation of a Simple HPLC Correlation Method for the Estimation of the Octanol-Water Partition Coefficients of Organic Compounds

Abstract

A simple reverse-phase high performance liquid chromatographic method is evaluated for the estimation of octanol-water partition coefficients (log P) of organic compounds by correlation with their chromatographic capacity factors (k′). Using an unmodified commercial octadecylsilane column and a mobile phase consisting of methanol and an aqueous buffer, a linear relationship is established between the literature log P values of 68 compounds and the logarithms of their k′ values. For the determination of the partition coefficients of unknowns, one of two sets of standards is used to calibrate the system, the choice being dependent on the hydrogen-bonding character of the compounds being evaluated. The overall method is shown to be rapid and widely adaptable and to give log P data which are comparable to results obtained by classical or other correlation methods.     

Validation Method for the Determination of Sulfonamide Residues in Bovine Milk by HPLC

A simple, rapid, sensitive and reliable high-performance liquid chromatographic method for the simultaneous determination of eight sulfonamides (SAs) in bovine milk was developed (sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxypyridazine, sufamonomethoxine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline) in bovine milk was developed. Samples were prepared by extraction with ethyl acetate and cleaning-up with an anion solid-phase extraction (SPE) column. Analytical separation was performed on an Inertsil ODS-3 column with photodiode-array detection at 270 nm under gradient condition. The whole procedure was evaluated according to the European Commission Decision 2002/657/EC. Specificity, decision limit (CCα), detection capacity (CCβ), trueness and precision were determined during the validation process. It was found that the analytes were isolated from spiked samples with good recoveries between 70.5 and 89.0%. The used analytical conditions allow to successively separating all the tested sulfonamides with good limit of detection between 0.8 and 1.5 μg L⁻¹.