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.     

Validation of a Novel HPLC Method for the Determination of Raloxifene and Its Pharmacokinetics in Rat Plasma

A novel HPLC method has been developed and validated for the determination of Raloxifene in rat plasma. Samples were prepared based on a simple protein precipitation. Separation of Raloxifene in plasma was performed on a C18 column, with a mobile phase of acetonitrile–ammonium acetate. Good linearity was demonstrated in the range of 0.2–75.0 μg mL⁻¹ (r = 0.9931). The method was used to measure the concentration and pharmacokinetics of Raloxifene in rat plasma after a single oral dose, and a linear pharmacokinetic profile of Raloxifene was found.     

Simultaneous determination of cefoxitin,cefuroxime, cephalexin and cephaloridine in plasma using HPLC and a column-switching technique

Summary A new high performance liquid chromatographic method was developed using a column-switching technique for the simultaneous determination of cephalexin, cefuroxime, cefoxitin and cephaloridine in plasma. The plasma samples were injected onto a precolumn packed with Corasil RP C₁₈ (37–50 m) after simple dilution with an internal standard solution in 0.01 M acetate buffer (pH 3.5). Polar plasma components were washed out using 0.01 M acetate buffer (pH 3.5). After valve switching, the concentrated drugs were desorbed in back-flush mode and separated on a Partisil ODS-3 column using acetonitrile in 0.02 M acetate buffer (pH 4.3) (1585, v/v) as the mobile phase. The method showed excellent precision with good sensitivity and speed with a detection limit of 0.5 g/ml. The total analysis time per sample was less than 25 min, and the mean coefficients of variation for intra- and inter-assay were both less than 4.9 %.This method has been successfully applied to plasma from rats after subcutaneous injection of cefuroxime.     

Development and Validation of an HPLC Method for the Determination of Dexamethasone, Dexamethasone Sodium Phosphate and Chloramphenicol in Presence of Each Other in Pharmaceutical Preparations

An HPLC method for the determination of dexamethasone, dexamethasone sodium phosphate and chloramphenicol in presence of each other in pharmaceutical preparations has been developed using a Shim-Pack CLC-ODS column (6.0 × 150 mm²). These analytes were separated under isocratic conditions. Various chromatographic parameters including linearity, precision and accuracy have been evaluated. The method was found to be suitable for analysis of these drug substances in presence of each other. The run time was less than 15 min. This method is suitable for application to various dosage forms.     

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 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.     

Development and Validation of a Liquid Chromatographic Method for Determination of Efavirenz in Human Plasma

A simple, rapid, and sensitive high-performance liquid chromatographic method for estimation of efavirenz in human plasma has been developed and validated. Chromatography was performed with C₁₈ analytical column and 50:50 acetonitrile–phosphate buffer (pH 3.5) as mobile phase. Compounds were monitored by UV detection at 247 nm. The retention time for efavirenz was 6.45 min and that for the internal standard, nelfinavir, was 2.042 min. Response was a linear over the concentration range of 0.1 μg–10 μg mL⁻¹ in human plasma. The method was simple, specific, precise and accurate and was useful for bioequivalence and pharmacokinetic studies of efavirenz.     

Off-line Coupling of Isotachophoresis and High Performance Liquid Chromatography for Determination of Flavonoids in Plant Extract

Summary The use of isotachophoretic sample pretreatment coupled with high performance liquid chromatography for the analysis of some flavonoids occurring in plant extracts of Hypericum perforatum and Crataegus sp. is described. The samples were extracted with methanol by means of sonication in low temperature. The optimal leading electrolyte was used 10 mM Cl^– as a leading ion in a buffer system at apparent pH^*=7.2 (adjusted by TRIS) and terminating electrolyte was 50 mM boric acid at apparent pH^*=8.2 (adjusted by barium hydroxide). The ITP electrolytes contained 20% (v/v) of methanol. To improve the sample pre-treatment, a pair of discrete ITP spacers defining the trapped constituents was used. Major components presented in the extracts were separated on a Discovery C18 and Discovery RP Amid C16 columns with a gradient mobile phase consisting of methanol, acetonitrile and diluted ortho-phosphoric acid. The quantification was performed by using external standards. The recoveries of the coupled ITP-HPLC analytical procedure were in the range of 91.2–95.6%.     

Dual injector solvent elution and focussing technique for the on-line analysis of solid-phase extraction cartridges in HPLC

Summary A new dual injector solvent focussing and elution technique developed for high-performance liquid chromatography (HPLC) greatly improves chromatographic efficiency for the on-line analysis of C₁₈ solid-phase extraction (SPE) cartridges. Solutions containing three benzene homologs were used to characterize the dual injector analysis technique and to compare the chromatographic efficiency of this method with conventional SPE analysis methods. Sampling was performed off-line using a glass precolumn cartridge (3 mm i.d. × 30 mm) packed with 15–35 μm C₁₈ silica. On-line cartridge analysis was achieved with two injection valves in either serial or parallel configuration. The injection loop of the first valve contains the eluting solvent, and the cartridge holder is connected in place of the injection loop of the second valve. When an injection is made, both valves are turned to the inject position, and the solvent plug is forced through the cartridge, focussing the analyte at the solvent front as it elutes the cartridge. Solvent focussing at the head of the column, resulting from preconditioning of the column with a small plug of water during injection, further minimizes the variance of the injection plug and improves the chromatographic efficiency. The technique has potential applications to environmental and biological fluid analysis where analyte preconcentration and resolution from the sample matrix components may be difficult with current SPE methods.     

Validation of a Stability-Indicating LC Method for Assay of Ezetimibe in Tablets and for Determination of Content Uniformity

A simple, precise, and accurate HPLC method has been developed and validated for assay of ezetimibe in tablets and for determination of content uniformity. Reversed-phase liquid chromatographic separation was achieved by use of phosphoric acid (0.1%, v/v)–acetonitrile 50:50 (v/v) as mobile phase. The method was validated for specificity, linearity, precision, accuracy, robustness, and solution stability. The specificity of the method was determined by assessing interference from the placebo and by stress testing of the drug (forced degradation). Response was a linear function of drug concentration in the range 20–80 μg mL⁻¹ (r = 0.9999). Intraday and interday system and method precision were determined. Accuracy was between 100.8 and 102.7%. The method was found to be robust, and was suitable for assay of ezetimibe in a tablet formulation and for determination of content uniformity. An erratum to this article can be found at     

Method Development and Validation of a Rapid Determination of Ropinirole in Tablets by LC-UV

A reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection was developed and validated for the determination of ropinirole (ROP) in tablets. The assay utilized UV detection at 250 nm and a Luna CN column (250 × 4.6 mm I.D, 5 μm). The mobile phases were comprised of acetonitrile: 10 mM nitric acid (pH 3.0) (75:25, v/v). Validation experiments were performed to demonstrate linearity, accuracy, precision, limit of quantitation (LOQ), limit of detection (LOD), and robustness. The method was linear over the concentration range of 0.5–10.0 μg mL⁻¹. The method showed good recoveries (99.75–100.20%) and the relative standard deviations of intra and inter-day assays were 0.38–1.69 and 0.45–1.95%, respectively. The method can be used for quality control assay of ropinirole.     

Development and Application of a Two-Phase Clean-Up System in Food Samples Prior to Fluorescence Analysis of Aflatoxins

A new method based on the use of a two-phase separation system is proposed for the clean-up of aflatoxins after their extraction from food samples. After extraction from the sample with an appropriate solvent, aflatoxins contained in organic solvent diffuse to the aqueous phase. At that stage their relative concentration is measured fluorimetrically at 350 nm (λ_exc). Different organic solvents were tested, and the composition of the aqueous phase was varied. The data obtained showed that the best efficiencies were observed with toluene and PBS-65% methanol. The method was simpler and shorter, and capable of monitoring aflatoxins in samples with a LOD equal to 0.3 μg kg⁻¹ (AFB₁). However, the proposed method shows limited selectivity and could thus serve as a screening method for total aflatoxins or be combined with chromatographic techniques for individual aflatoxin determination.     

Inertness and stability of a maltose-silica for the separation of proteins by HPLC

Summary A stationary phase consisting of maltose on a silica support, designed for the separation of proteins, is described. When maltose is coupled to aminopropylsilica an effective shielding of the silica surface can be obtained. A size exclusion experiment is used to investigate pore structure and the behaviour of proteins. The stability of the surface layer is studied, as influenced by silica pretreatments and cross-linking reactions. Inertness is studied via the denaturation of trypsin in columns of different length at a number of temperatures. An example of a derivatization of the maltose layer is given which demonstrates its use as an interactive separation medium.     

Validation of an HPLC Method for the Determination of Valdecoxib and its Degradation Product: a Mixture of α- and β-n-Lactosyl Sulfonamide Anomers

An HPLC method has been developed for the separation of valdecoxib and a degradation product consisting of α and β-N-lactosyl sulfonamide, i.e. α and β anomers (SC-77852). Best results were achieved with a Chromolith Performance RP-18e column (100 mm × 4.6 mm), macropore size 2 μm, mesopore size 13 nm, with an eluent of methanol:water containing a 1% solution of TEA (36:64 v/v), pH 7.4 (adjusted with 85% orthophosphoric acid), at 22 °C. Detection was at 220 nm. The method was validated for its selectivity, linearity, precision (repeatability) and robustness. Quantitation and detection limits were determined for both valdecoxib and SC-77852. Method robustness was further evaluated by performing 2³ full factorial design experiments. The final step, optimisation of the variables, was performed using response surface design. The validated method was used for assay of valdecoxib and SC-77852 in Bextra^® film-coated tablets.     

HPLC Method for Determination of Rosiglitazone in Plasma

A fast and sensitive high performance liquid chromatography method for quantitative determination of rosiglitazone in human plasma has been developed. The extraction from plasma was performed using solid-phase extraction (SPE) on C4 silica (100 mg) disposable extraction cartridges (DEC). The separation of rosiglitazone and two metabolites was achieved on a Phenomenex® Synergi 4 µm MAX-RP (150 × 4.6 mm) column, protected by a guard column. The mobile phase was 0.01 M ammonium acetate, pH 7.0 - acetonitrile (65:35, v/v). (3S)-3-OH-quinidine was used as internal standard. The analytes were detected using fluorescence detection. The method was validated. The limit of quantitation was 1 ng mL⁻¹ and the detection limit was 0.25 ng mL⁻¹ for rosiglitazone in human plasma. The recovery was 90% for rosiglitazone. Linearity was observed over a range of 1-1000 ng mL⁻¹ (r²=0.9959). The intra- and inter-day precision (C.V.) did not exceed 8.7 %. Applicability of the method was demonstrated by a clinical pharmacokinetic study. A healthy volunteer received in two separate phases 4 mg and 8 mg rosiglitazone maleate as a single oral dose. Plasma concentrations were measured for 24 h in both phases.     

Validation of an HPLC Method for Determination of Cefepime (a Fourth-Generation Cephalosporin). Determination in Human Serum, Cerebrospinal Fluid, and Urine. Pharmacokinetic Profiles

A high-performance liquid-chromatographic method with detection at 256 nm has been developed and validated for analysis of cefepime in several biological matrices. Serum samples were deproteinized with acetonitrile and extracted once with dichloromethane. For urine and cerebrospinal fluid samples, only a microfiltration step was necessary. The method was validated in accordance with the recommendations of the International Conference on Harmonization (ICH), the Food and Drug Administration (FDA), and the Center for Drug Evaluation and Research (CDER). The method was used to determine levels of the drug in the serum, cerebrospinal fluid, and urine of twelve patients treated with Maxipime. The results obtained were compared with those from previously published HPLC methods.     

Optimization and Validation of an HPLC-UV Method for Determination of Tranexamic Acid in a Dosage Form and in Human Urine

A simple and reliable high-performance liquid chromatographic method with UV detection at 245 nm has been developed and validated for determination of tranexamic acid (TA) in a dosage form and in human urine. Before injection samples were derivatized with phenyl isothiocyanate (PITC). The reaction temperature, reaction time, and concentration of PITC used for derivatization were optimized. Chromatographic separation was on a C₁₈ column with a 65:35 (v/v) mixture of 10 mM phosphate buffer, pH 3.6, and acetonitrile as mobile phase. Heptaminol hydrochloride was used as internal standard.     

Development and Validation of a LC Method for the Determination of Pramipexole Using an Experimental Design

A rapid and sensitive RP-HPLC method with UV detection for routine control of pramipexole in tablets was developed. Chromatography was performed with mobile phase containing a mixture of acetonitrile/phosphate buffer (60/40; v/v) with a flow rate of 0.8 mL min⁻¹. Quantitation was accomplished with the internal standard method; the procedure was validated by linearity (correlation coefficient = 0.99892), accuracy, robustness and intermediate precision. Limit of quantitation and limit of detection were found to be 4.5 μg and 1.4 μg respectively, which indicates the method is highly sensitive. Experimental design was used during validation to calculate method robustness and intermediate precision, for robustness test three factors were considered; percentage v/v of acetonitrile, flow rate and pH; an increase in the flow rate results in a decrease of concentration found of the drug, while the percentage of organic modifier and temperature have no important effect on the response. For intermediate precision measure the considered variables were: analyst, equipment, days and obtained RSD value (0.56%, n=24) which indicated a good precision of the analytical method. The method was found to be applicable for determination of the drug in tablet formulations and the results of the developed method were compared with those of the UV spectrophotometric method to access the active pramipexole content. Revised: 13 March and 25 April 2006     

Development and Validation of a Stability-Indicating LC Method to Quantify Hydrochlorothiazide in Oral Suspension for Pediatric Use

A stability-indicating reversed-phase high-performance liquid chromatography (LC) method was developed and validated for the determination of hydrochlorothiazide in an oral suspension. Isocratic chromatography was performed on a C₁₈ column with 0.1 M sodium phosphate buffer pH 3.0/acetonitrile (70:30 v/v) as mobile phase, at a flow rate of 1.3 mL min⁻¹, and UV detection at 254 nm. The method was linear (r ² = 0.9998), accurate (mean recovery = 100.3%), and precise (RSD <2%). It was also validated for specificity and robustness. The method was successfully applied for the quality control analysis of a new pharmaceutical formulation of HCTZ for pediatric use.     

Development and Validation of a Micellar Liquid Chromatographic Method with UV Detection for Determination of Azithromycin in Tablets and Capsules

A rapid and simple micellar liquid chromatographic method that does not require use of specific chromatographic columns has been developed and validated for azithromycin determination. The method uses a Hypersil C₁₈ column at 60 °C, 1-butanol–pH 6.86 phosphate buffer solution–water, 15:25:60 (v/v), containing 0.10 M sodium dodecyl sulfate, as mobile phase, and UV-detection at 215 nm. Different characteristics of the method were validated satisfactorily. The specificity, accuracy, linearity, precision (repeatability), and robustness of the method were demonstrated. The method proved suitable for determination of the azithromycin content of capsules and uncoated tablets.Revised: 5 February and 11 March 2004