Reversed-phase Column Liquid Chromatographic Method Research Articles

Determination of isosorbide nitrate and its analogues in pharmaceuticals by high-performance liquid chromatography

A reversed-phase column liquid chromatographic method was developed for analysis of isosorbide dinitrate (ISDN), isosorbide 5-mononitrate (IS5MN) and isosorbide 2-mononitrate (IS2MN) and its pharmaceuticals. Chromatography is performed to Bondclone ODS column using a mobile phase consisting of acetonitrile-PIC B6 buffer, pH 4.75 (13:87) with ultraviolet wavelength at 220 nm. The linearity calibration range was 0.05 mg/ml to 2.5 mg/ml (r = 0.9999), and recoveries were generally greater than 98.0%

Development and validation of a reversed-phase column liquid chromatographic method for simultaneous determination of two novel gliptins in their binary mixtures with Metformin

A new, simple, accurate, and precise liquid chromatographic method has been developed and validated for the determination of two novel dipeptidylpeptidase-4 (DPP-4) inhibitors; namely vildagliptin (VLG) and saxagliptin HCl (SXG) simultaneously in their binary mixtures with metformin HCl (MET). Chromatographic separation was achieved on an Inertsil® CN-3 column (250 mm x 4.6 mm, 5 µm). Isocratic elution using a mobile phase of potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile (15:85, v:v) at a flow rate of 1 mL/min with UV detection at 208 nm was performed. The liquid chromatographic method was used for the simultaneous determination of either VLG, SXG and MET in the range of 5-200, 0.5-20 and 50-2000 μg/mL, respectively. The methods developed were satisfactorily applied to the analysis of the pharmaceutical formulations and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms.

Development and Validation of a Reversed-Phase Column Liquid Chromatographic Method for the Determination of Five Cephalosporins in Pharmaceutical Preparations

Abstract A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters μBondapak® C18 column (250 × 4.6 mm id, 10 μm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)–acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30–300, 3–30, and 15–120 μg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.

Development and Validation of a Reversed-Phase Column Liquid Chromatographic Method for the Determination of Five Cephalosporins in Pharmaceutical Preparations

A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.

Validated RP-LC Method for Simultaneous Determination of Zofenopril and Hydrochlorothiazide in Pharmaceutical Preparations

A simple, selective, and precise reversed-phase column liquid chromatographic method has been developed and validated for the simultaneous determination of zofenopril (ZOF) and hydrochlorothiazide (HCT) in pharmaceutical preparations. Analyses were carried out on a C18 column using methanol-water (pH 2.5 with H 3 PO 4 ) as the mobile phase, delivered in a gradient mode. Detection was performed using an UV―vis detector monitored at 270 nm. Quantitation was achieved using an external calibration curve. The linearity for ZOF concentrations ranging between 1.0―70.0 μg/mL, and between 2.5―35.0 μg/mL for HCT (r > 0.999) was established. The recovery (R%) of the active ingredients from the samples ranged between 99.42% and 100.67%. Intra- and inter-day precisions were less than 1.5%. The limits of detection (LOD) and quantitation (LOQ) were 0.129 and 0.292 μg/mL for ZOF, and 0.183 and 0.556 μg/mL for HCT, respectively. There was no background interference for either of the two active ingredients during chromatographic analysis. The proposed method could be used for quality control of these two componenets in combination.

RP-LC Determination and Pharmacokinetic Study of Ferulic Acid and Isoferulic Acid in Rat Plasma After Taking Traditional Chinese Medicinal-Preparation: Guanxinning Lyophilizer

A sensitive, simple, and accurate method for determination and pharmacokinetic study of ferulic acid and isoferulic acid in rat plasma was developed using a reversed-phase column liquid chromatographic (RP-LC) method with UV detection. Sample preparations were carried out by protein precipitation with the addition of methanol, followed by evaporation to dryness. The resultant residue was then reconstituted in mobile phase and injected into a Kromasil C18 column (250 × 4.6 mm i.d. with 5 μm particle size). The mobile phase was methanol-1% formic acid (33:67, v/v). The calibration plots were linear over the range 5.780–5780 ng·mL−1 for ferulic acid and 1.740–348.0 ng·mL−1 for isoferulic acid. Mean recoveries were 85.1% and 91.1%, respectively. The relative standard deviations (RSDs) of within-day and between-day precision were not above 15% for both of the analytes. The limits of quantification were 5.780 ng·mL−1 for ferulic acid and 1.740 ng·mL−1 for isoferulic acid. This RP-LC method was used successfully in pharmacokinetic studies of ferulic acid and isoferulic acid in rat plasma after intravenous injection of Guanxinning Lyophilizer.

LC-PAD Determination of Mescaline in Cactus “Peyote” (Lophophora williamsii)

A reversed-phase column liquid chromatographic method for the separation and quantification of mescaline present in “peyote” has been developed using a Symmetry C18 column and isocratic profile. The method can be utilised for the quantitative determination of other alkaloids. This method is economical in terms of the time taken and the amount of solvent used for each analysis. The validity of the method with respect to analysis was confirmed by comparing the UV spectra of peak with the reference compound (mescaline) using a photodiode array detector. The assay method described is simple, rapid and accurate, and may form part of future drug authentication protocols.

Stability-Indicating Reversed-Phase Liquid Chromatographic Method for Simultaneous Determination of Simvastatin and Ezetimibe from Their Combination Drug Products

A simple, precise, and rapid stability-indicating reversed-phase column liquid chromatographic (RP-LC) method has been developed and subsequently validated for simultaneous estimation of atorvastatin (ATV) and ezetimibe (EZE) from their combination drug product. The proposed RP-LC method utilizes a LiChrospher 100 C18, 5 microm, 250 x 4.0 mm id column at ambient temperature; the optimum mobile phase consists of acetonitrile-water-methanol (45 + 40 + 15, v/v/v) with apparent pH adjusted to 4.0 +/- 0.1; mobile phase flow rate of 1.0 mL/min; and UV detection at 250 nm. ATV, EZE, and their combination drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. There were no other coeluting, interfering peaks from excipients, impurities, or degradation products due to variable stress conditions, and the method is specific for the estimation of ATV and EZE in the presence of degradation products. The response was linear over the concentration range of 1-80 microg/mL for ATV and EZE. The mean recoveries were 99.27 and 98.5% for ATV and EZE, respectively. The intermediate precision data were obtained under different experimental conditions, and the calculated value of the coefficient of variation was found to be less than the critical value. The proposed method can be useful in the quality control of bulk manufacturing and pharmaceutical dosage forms.

RP-HPLC Determination of Linarin in Beagle Dog Plasma After Administration of Yejuhua Injection

A sensitive, simple, and accurate reversed-phase column liquid chromatographic (RP-LC) method with daidzein as an internal standard and UV detection at 348 nm has been developed for determination of linarin in beagle dog plasma. Plasma protein was precipitated by addition of acetonitrile and the remaining solution was evaporated to dryness. The resulting residue was then reconstituted in methanol and injected on to a 250 mm × 4.6 mm i.d., 5 μm particle, ODS analytical column. The mobile phase was a gradient prepared from acetonitrile and an aqueous solution (0.4%) of phosphoric acid; the flow rate was 1.0 mL min−1. Response was a linear function of concentration over the range 3.4–1,373.3 ng mL−1; the correlation coefficient (R 2) was 0.993. Mean recovery was 74.2%. Within-day and between-day precision were better than 8.8% relative standard deviation (RSD). The limit of quantification was 3.4 ng mL−1. This RP-LC method was used successfully in pharmacokinetic studies of linarin in beagle plasma after administration of Yejuhua injection.

An improved method for the analysis of sennosides in Cassia angustifolia by high-performance liquid chromatography.

A reversed-phase column liquid chromatographic method for the analysis of sennosides A and B present in leaf and pod extracts of Cassia angustifolia has been developed using a Symmetry C18 column and a linear binary gradient profile. The method can be utilised for the quantitative determination of other sennosides as a baseline resolution for most of the constituents was achieved. The method is economical in terms of the time taken and the amount of solvent used (25 mL) for each analysis. The validity of the method with respect to analysis was confirmed by comparing the UV spectra of each peak with those of reference compounds using a photodiode array detector.

Determination of cis and trans isomers of monocrotophos in technical products by reversed-phase column liquid chromatography

A simple reversed-phase column liquid chromatographic method for the determination of cis and trans isomers of monocrotophos (MCP) using a C 18 column, aqueous acetonitrile as eluent and UV detection at 218 nm was developed. The method was used for quality assurance and to study the relative stabilities of cis and trans isomers in technical products of MCP.

High-performance liquid chromatographic method for potency determination of cephalexin in commercial preparations and for stability studies

A reversed-phase column liquid chromatographic method was developed for the assay of cephalexin in bulk drugs and pharmaceutical preparations. An equation was derived showing a linear relationship between peak-area ratio of cephalexin to acetaminophen (internal standard) and the cephalexin concentration over a range of 0.2–1.75 mg/ml ( r = 0.9999). Standard addition recoveries were generally greater than 99.5%. The relative standard deviations were between 0.38 and 0.63% in the within-day assay, and 1.05% in the between-day assay. The column liquid chromatographic assay results were compared with those obtained from a microbiological assay, which indicated that the proposed method is a suitable substitute for the microbiological method for potency assays and stability studies of cephalexin preparations.

Column liquid chromatography and microbiological assay compared for determination of cefadroxil preparations

A reversed-phase column liquid chromatographic method was developed for the assay of cefadroxil in bulk drugs and pharmaceutical preparations. An equation was derived showing a linear relationship between peak-area ratios of cefadroxil to dimethylphthalate (internal standard) and the cefadroxil concentration over a range of 0.02–0.8 mg/ml ( r = 0.9999). Standard addition recoveries were generally greater than 97.7%. The coefficients of variation in the within-day assay were between 0.36 and 0.65, and in the between-day assay was 0.71%. The column liquid chromatographic assay results were compared with those obtained from a microbiological assay, which indicated that the proposed method is a suitable substitute for the microbiological method for potency assays and stability studies of cefadroxil preparations.

High-performance liquid chromatographic method for potency determination of amoxicillin in commercial preparations and for stability studies.

A reversed-phase column liquid chromatographic method was developed for the assay of amoxicillin and its preparations. The linear calibration range was 0.2 to 2.0 mg/ml (r = 0.9998), and recoveries were generally greater than 99%. The high-performance liquid chromatographic assay results were compared with those obtained from a microbiological assay of bulk drug substance and capsule, injection, and granule formulations containing amoxicillin and degraded amoxicillin. At the 99% confidence level, no significant intermethod differences were noted for the paired results. Commercial formulations were also analyzed, and the results obtained by the proposed method closely agreed with those found by the microbiological method. The results indicated that the proposed method is a suitable substitute for the microbiological method for assays and stability studies of amoxicillin preparations.

High-performance liquid chromatographic method for the determination of cloxacillin in commercial preparations and for stability studies

A reversed-phase column liquid chromatographic method was developed for the assay of cloxacillin and its preparations. The linear calibration range was 0.2–3.0 mg/ml ( r0.9998) and recoveries were generally greater than 99%. The relative standard deviation was 0.13% ( n10). The high-performance liquid chromatographic assay results were compared with those obtained from a microbiological assay for bulk drug substance, capsule, injection and syrup formulations containing cloxacillin and degraded cloxacillin. At the 99% confidence level, no significant inter-method differences were noted for the paired results. Commercial formulations were also analysed and the results obtained by the proposed method closely agreed with those found by the microbiological method. The results indicated that the proposed method is a suitable substitute for the microbiological method for assays and stability studies of cloxacillin preparations.

Determination of remoxipride in plasma and urine by reversed-phase column liquid chromatography

A reversed-phase column liquid chromatographic method for the determination of remoxipride, a novel antipsychotic drug, in biological fluids is described. A simple one-step extraction is used followed by liquid chromatography on a 3-μm octadecylsilica column and ultraviolet absorbance detection. The method is accurate and precise for clinical remoxipride levels in both plasma and urine. For situations where a higher sensitivity is necessary a two-step extraction and a modified mobile phase are used. With this modification plasma concentrations down to 2 n M can be determined with acceptable precision.