Analysis of Dexamethasone Acetate in Pharmaceutical Formulations by HPLC

Abstract

A rapid and effective high-pressure liquid chromatographic method has been developed for the quantitative determination of dexamethasone 21 acetate in pharmaceutical formulations. Sample preparation employs a simple extraction procedure and analysis is carried out on a reversephase chromatographic system using a LiChrosorb RP 18 column and a water-acetonitrile as mobile phase. The extraction procedure gives quantitative recovery and chromatographic results show that drug levels of as 0.1 ppm can be conveniently analyzed without significant background interferences.     

An Improved Microanalytical Procedure for the Quantitation of Procainamide and N-Acetyl Procainamide in Serum by High-Performance Liquid Chromatography

Abstract

A high-performance liquid chromatographic method for analysis of procainamide (PA), and N-acetyl procainamide (NAPA) is presented. Sample preparation employs a simple base-acid double extraction procedure and analysis is carried out on a reverse phase chromatographic system using a μBondapak C₁₈ column and buffered aqueous acetonitrile as the mobile phase. The extraction procedure gives quantitative recovery of both PA and NAPA, and chromatographic results show that drug levels of as low as 0.3 mg per liter of serum can be conveniently analyzed without significant background interferences. The small volume (0.2 ml) of serum needed to perform an analysis makes this method suitable for pharmacokinetic studies in humans and animals as well as for clinical therapeutic drug monitoring studies.     

Role of the Dissolution Mechanism in Determining Chromatographic Separation of Biogenic Amines from Their Precursors and Metabolites by HPLC-EC

Abstract

The current study was designed to elucidate the theoretical basis for chromatographic separation of biogenic amines on an octadecyl-silica (C-18) reverse phase column by determining the intermolecular forces between the solute and the stationary phase. The solutes mass transfer diffusion and the heat effect between solutes and stationary phase were assessed by a convenient method. This study demonstrates that the dissolution mechanism plays a major role in the process of chromatographic resolution of biogenic amines and their precursors and metabolites by HPLC-EC.     

Simultaneous Determination of Diazepam and its metabolites in Plasma by High-Performance Liquid Chromatography

Abstract

A reversed phase high-performance liquid chromatographic method (HPLC) for the simultaneous determination of diazepam and its three active metabolites, nordazepam, oxazepam and temazepam, in plasma was proposed. The compounds were isolated by solid-phase extraction. The chromatographic mobile phase was metanol-water (55:45, v/v) at a flow rate of 1 mL/min. UV detection was performed concurrently at 240 and 254 nm.     

High Pressure Liquid Chromatographic Analysis and Dissolution of Famotidine in Tablet Formulation

Abstract

A reversed phase high pressure liquid chromatographic method was developed for the quantitation of famotidine in tablet formulation using a mobile phase consisting of 0.1M phosphate buffer (84%), acetonitrile (11%) and methanol (5%) at a pH of 6.5. The detection wavelength was set at 285 nm. The method is precise and adaptable for quality control purposes. The use of the analytical method hi studying tablet dissolution is described.     

Thin Layer Chromatographic Analysis of Basic and Quaternary Drugs Extracted as Bis(2-ethylexyl)phosphate Ion-Pairs

Abstract

Thin layer chromatography in the normal and reversed phase mode is evaluated as a qualitative analysis method for various basic and quaternary drugs extracted as bis(2-ethylhexyl)phosphate ion-pairs. A combination of two thin layer chromatographic systems, a reversed phase system and a fairly apolar normal phase system, is shown to cover the analysis of drugs with different grades of polarity. Based on that, a method for screening of urine samples for drugs is described.     

Quantitative HPLC Analysis of Plasma Amino Acids as Orthophthaldialdehyde/Ethanethiol Derivatives

Abstract

A reverse phase high performance liquid chromatographic method for the analysis of plasma amino acids is described. The method employs pre-column derivatization with o-phthaldialdehyde using ethanethiol as the reducing agent. The analysis shows good linearity and reproducibility. An average overall difference of 12% was seen for results obtained by the HPLC method versus those obtained with an amino acid analyzer. The chromatographic parameters of buffer concentration and column temperature were also examined.     

Determination of Tetracycline and Related Compounds by High-Performance Liquid Chromatography

Abstract

An isocratic high-performance liquid chromatography method for the determination of tetracycline and its related compounds is described. The method uses a reverse phase (C₁₈) column, a modified acetonitrile/water mobile phase, and banzoic acid as the internal standard. Elution of all compounds of interest is complete within seven minutes. Results are presented for thirteen commercial capsule formulations and are compared with results by microbiological assay and thin-layer chromatographic methods.     

A Simultaneous Analysis by High Performance Liquid Chromatography of Bamipine Combined with Tricyclic Antidepressants and/or Antipsychotics in Dosage Forms

Abstract

A reversed phase high-performance liquid chromatographic method is described for the simultaneous determination of antihistamines, tricyclic antidepressants and anti-psychotics in pharmaceutical formulations and in spiked placebos. The separation was performed on an octadecyl-silica column using acetonitrile: tetrahydrofuran: 0.015 M aqueous ammonium acetate (53:42: 5) as mobile phase. The presence of ammonium acetate both shortens the elution time and improves the symmetry of the chromatographic peaks. Measurements were made at 251 nm.     

High Performance Liquid Chromatographic Analysis of Penicillin V Solid Dosage Forms

Abstract

An isocratic high performance liquid chromatographic (HPLC) method for the determination of Penicillin V in solid dosage forms is described. A reverse phase RP-8 column and a mobile phase of 52% methanol in 0.05 M phosphate buffer (pH 3.3) were employed. Detection was effected at 254 nm. The results obtained are compared with those from the iodometric method.     

Quantitative Determination of Methyl Red Adsorption on Stationary Phases Used in Liquid Chromatography

Abstract

The method described is a modification of the dye adsorption method, first published by Shapiro and Kolthoff. It is reproducible and allows the estimation of the relative amount of the reachable free silanol groups on silica gels and reversed phase materials which are frequently used as stationary phases in liquid chromatography. Results obtained with commercially available thin layer and high performance liquid chromatographic materials, as well as with self-made reversed phase materials, are reported.     

Determination of Melphalan and Chlorambucil in Tablet Dosage form Using High-Performance Liquid Chromatography and Amperometric Detection

Abstract

We developed a liquid chromatographic method for the measurement of melphalan and chlorambucil in tablets, using a reversed phase C18 column with isocratic elution and amperometric detection. For melphalan the potential was set at +0.95V and chlorambucil at + 0.90V. The method is simple, sensitive and may also be applicable to pharmacokinetic studies.     

Purification of Commercially Prepared Bovine Trypsin by Reverse Phase High Performance Liquid Chromatography

Abstract

A reverse phase high performance liquid chromatographic method for the purification of milligram amounts of commercially prepared bovine trypsin is described. Increased specific enzymatic activity is observed in the purified material. The advantages of using purified trypsin in protein digestions as well as the potential application of reverse phase high performance liquid chromatography for enzyme characterization are described.     

The Determination Ofritalinic Acid in Urine by Gas Chromatography

Abstract

A gas chromatographic method for the analysis of ritalinic acid, the major metabolite of methylphenidate, in urine has been developed. Solid phase extraction is employed to afford high recovery of ritalinic acid. The method has a lower limit for reliable quantitation of 1 μ/ml. The reliability and sensitivity of this method make it suitable for human studies.     

Liquid Chromatographic Analysis for Flecainide with Use of a Microbore Column and Ultraviolet Detection

Abstract

We describe a simple, isocratic high-performance liquid chromatographic method for measuring the oral antiarrhythmic agent flecainide acetate in serum or plasma. Sample analysis involves a simple organic extraction followed by chromatography on a microbore reverse phase column with ultraviolet detection at 298 nm.     

Quantitative Analysis of Terbutaline (Bricanyl®) in Human Plasma with Liquid Chromatography and Electrochemical Detection Using On-Line Enrichment

Abstract

A liquid chromatographic method with electrochemical detection (LC-EC) has been developed for the quantitative analysis of terbuta-line in the range 5–50 pmole ml^?1 of human plasma. Terbutaline is isolated from 2 ml of plasma on an ion-exchange column and the eluate is concentrated on a hydrophobic precolumn on-line in the chromatographic system. The precolumn is then back-flushed for further separation onto a hydrophobic analytical column. The mobile phase is a methanol-aqueous buffer to which sodium perchlorate is added to achieve resolution from interfering peaks. A glassy carbon electrode is used for detection. Comparison has been made with gas chromatography-mass spectrometry (GC-MS) to examine the accuracy of the method.     

Qualitative and Quantitative Analysis of Unresolved Responses In Liquid Chromatoraphy With Fourier Transform Infrared Spectroscopic Detection By Using the Kalman Filter

Abstract

The optimization of chromatographic separations is hindered by difficulties in establishing the identities of components, and by the need to have well-resolved chromatographic peaks for commonly-used methods of quantitation. Full spectra methods, such as Fourier transform infrared spectroscopy, may assist in establishing identities, but are hampered by poor sensitivity. A method is proposed which efficiently reduces the large amounts of spectral data obtained in such cases, and enhances signal-to-noise ratios to permit identification and quantitation of components present in well-and poorly-resolved chromatographic peaks obtained under nonoptimal conditions. the method is based on combined Gram-Schmidt orthogo-nalization for removal of the dominant response from the mobile phase, followed by Kalman filtering for qualitative and quantitative analysis of averaged spectra. the method is demonstrated for infrared detection of a reverse-phase separation of a five-component mixture. Although Kalman filtering is effective at enhancing weak     

High Performance Liquid Chromatographic Determination of Triazolam in Human Serum

Abstract

A high performance liquid chromatographic method which utilizes UV-detection has been developed for the sensitive and specific determination of triazolam in human serum. Using 8-chloro-6-phenyl-l-ethoxymethyl-4H-s-triazolo[4, 3-a][1, 4]benzodiazepine as an internal standard, serum samples were buffered with 2 ml of 4M NaOH and extracted twice with 5 ml aliquots of toluene. The combined toluene extracts were evaporated to dryness and the residue dissolved in the chromatographic mobile phase. The samples were chromatography on a microparticulate reverse-phase column using a 0.06M acetic acid:acetonitrile (61:39) mobile phase. Known metabolites of triazolam did not interfere in the analysis. A linear relationship between peak height ratios and concentrations was observed, with the lower limit of detection being approximately 1 ng of triazolam. The utility of the method was demonstrated by administering therapeutic doses of the drug to human volunteers and monitoring serum triazolam concentrations as a function of time.     

Determination of Ethosuximide,Phenobarbital, Carbamazepine,Carbamazepine Epoxide and Phenytoin in Serum by high performance liquid chromatography using Radially compressed Columns and an Aqueous methanolic mobile phase

Abstract

A liquid chromatographic method for the determination of antiepileptic drugs in serum is described. The drugs were adsorbed on activated charcoal from which they were recovered by extraction with methylene chloride. The organic extracts were evaporated to dryness and the residues were dissolved in small volumes of the mobile phase. The extracts were clean. Only trace amounts of endogenic compounds were detected. The chromatographic separation was performed with a radially compressed column (C18) that was used daily for several months.     

Evaluation of novel dendrimer chiral stationary phases using HPLC

Summary The reversed phase chromatographic properties of the [G1]-L-glutamic and ethyl ester-AC-silica (1), [G2]-L-glutamic acid ethyl ester-AC-silica (2) and the [G1]-L-glutamic acidt-butyl ester-AC-silica (3) dendrimer stationary phases were evaluated. Initial studies involved the comparison between these phases with a classic reversed phase (i.e. ODS1) by the separation of a standard reversed phase test mixture composed of dimethylphthalate, nitrobenzene, anisole, diphenylamine and fluorene. Separations were achieved with comparable performance to those obtained with the conventional reversed phase (ODS1). However, it was apparent that the chromatographic selectivity exhibited by the dendrimer stationary phases was different from that of the ODS1 phase. On a per mole basis, the dendrimers exhibited similar (and sometimes greater) affinity for these analytes compared with the ODS1 ligand. Subsequent chromatographic experiments were conducted upon the dendrimer chiral stationary phases using chiral analytes under reversed phase and normal phase conditions. Chiral resolution was not observed.