A Direct and Sensitive Method for the Determination of Salicylamide in Microplasma Samples by High-Performance Liquid Chromatography Using Fluorescence Detection

Abstract

A quantitative analysis of salicylamide in microplasma volumes by high-performance 1iquid chromatography using fluorescence detection is reported. The procedure is extremely simple and very rapid, involving the direct introduction of the plasma sample on the HPLC column. The assay procedure is linear over the concentration range studied, 0–100 ng/ml with correlation coefficient for the linear regression, r = 0.998. This assay procedure enables the detection of salicylamide as low as 5.0 ng/ml in plasma, using sample volume of 100 μl.     

High Performance Liquid Chromatographic Determination of (-)-N-Formylnorephedrine in Plasma

Abstract

An HPLC procedure for the detection and quantitative estimation of (-)-N-formylnorephedrine in rabbit plasma had been developed. The procedure involved the extraction of (-)-N-formylnorephedrine from plasma spiked with the internal standard (phenacetin), using ethyl acetate. The ethyl acetate extract is evaporated under nitrogen and the residue is reconstituted in water and injected onto the column. A u-Bondapak-C18 column 30 cm × 3.9 mm ID was used. The mobile phase is 20% acetonitrile in water; at a flow rate of 1.5 ml/min and uv detection at 256 nm. A linear relationship between concentration and peak height ratio (I/internal standard) was obtained (r = 1.00). The reported procedure allows the measurement of (-)-formylnorephedrine in concentrations as low as 150 ng/ml of plasma with total procedure time of about 10 min. The applicability of the procedure to pharmacokinetic studies is illustrated and metabolites are shown not to interfere with the assay procedure.     

HPLC Analysis of Methoxamine in Rabbit Plasma and Pharmaceutical Formulations

Abstract

A rapid, selective and simple high performance liquid chromatographic (HPLC) assay for methoxamine HC1 has been developed. The analytical procedure involved the use of internal standardization method (1-norephedrine). It has been applied for the qualitative and quantitative determination of methoxamine HC1 in rabbit plasma and in pharmaceutical formulations using an adsorption column in an isocratic mode, with resulting relative standard deviations of 1.7% and 3.3%, respectively. The applicability of the assay procedure to pharmacokinetic studies was demonstrated. Detection limits were as low as 15ng for a 30 ul injection and the determination time was less than 6 minutes.     

Quantitation of R-836, a New Oral Bronchodilator,by High Performance Liquid Chromatography using Manual or Robotic Sample Preparation

Abstract

A simple and selective high performance liquid chromatography (HPLC) method has been developed for the quantitation of R-836 (an investigational oral bronchodilator) in human plasma and urine, dog plasma and urine, and rat plasma. The method consists of reversed-phase HPLC with ultraviolet detection. Sample preparation involved a one-step protein precipitation procedure and was performed both manually and by a Zymate robotic system. Precision and accuracy results showed excellent reproducibility; results using the robotic procedure were slightly better than the manual procedure. The robotic procedure was capable of preparing the samples with minimal operator handling.     

Single Column HPLC Method for Drug Level Monitoring by Direct Plasma Sample Injection. Application to 6-Mercaptopurine,Theophylline and Chlorpromazine

Abstract

An HPLC method with direct plasma sample injection onto a reverse phase column and stepwise elution was applied to the drug level monitoring of 6-mercaptopurine, theophylline and chlorpromazine by using spectrophotometric or electrochemical detection. The analysis of the drug spiked in human plasma was quantitative, and 100% of the drug was recovered regardless of the entity free or bound to plasma protein. Owing to a preliminary procedure of protein coating on the ODS silica gel the column characteristics were somewhat deteriorated, but accurate analyses could be achieved by a single column method including the simultaneous determination of some metabolites of the drug.     

The Analysis of Putrescine in Plant Samples by Automated Hplc

Abstract

The quantitative analysis of putrescine from plant tissue can be achieved using isocratic reversed-phase high performance liquid chromatography (HPLC). After preliminary extraction and clean up involving an ion exchange purification step, the isolated diamines are derivatised with benzoyl chloride for determination by HPLC. Automation of the HPLC step has led to a considerable saving in time for the total analysis. Potential problems associated with the analytical procedure are described.     

Assay of the Anti-Inflammatory Compound CGS 5391 B in Blood Plasma by Automated HPLC

Abstract

An automated HPLC method for the quantitative determination of the anti-inflammatory compound CGS 5391B in blood plasma was devised and tested. The method provides quantitation in the concentration range of 1 to 200 μg/ml of drug in plasma, with an average recovery of 96.6±6.0%.     

HPLC Separation of Tautomeric Compounds of 4-Aminoisoxazolyl- 1,2-Naphthoquinone. III

Abstract

This paper reports the development of a simple, precise and specific HPLC procedure for the determination of two new methylated isoxazolylnaphthoquinones with an amine group in the 4-position of the isoxazole ring, which are examples of exocyclic tautomers.

The analytical procedure involved the use of the internal standardization method which was applied for the qualitative and quantitative determination of both compounds using a C-18 Lichrosorb column in an isocratic mode and sulfadiazine as internal standard.     

Measurement of Nicotine in Plasma by High-Performance Liquid Chromatography

Abstract

A new procedure has been developed to measure nicotine in blood plasma by high-performance liquid chromatography (HPLC). Nicotine is extracted from plasma by elution with cholorform. Final determination is achieved by isocratic HPLC with ultraviolet detection. Twenty microliters of plasma extract is deluted over a silica column at a flow rate of 1.0 ml/min with a dioxane:isopropanol:NH₄OH (80:3.0:0.4) mobile phase. The procedure is sensitive to 0.05 ug of nicotine per ml of plasma and is linear within the range of 0.05 to 10.0 ug/ml of plasma. When a known amount of nicotine was added to plasma, the concentration of nicotine measured averaged 99.9 + 3.9 (S.D.)% of the known concentration. The within-sample coefficient of variation was 3.9%     

Liquid Chromatographic Method for Determination of Free and Niosome‐Entrapped Nimodipine in Mouse Plasma and Different Tissues

Abstract

A rapid HPLC method for the quantification of nimodipine in mouse plasma and tissues has been developed in this study, with simple procedure of sample preparation by one‐step protein precipitation. The results of HPLC analysis indicated that linear calibration curves were obtained over the concentration range 0.10–10.00 µg/ml for plasma, 0.10–20.00 µg/g for heart, liver, spleen, kidneys, and brain, and 1.00–200.00 µg/g for lung, respectively. The desirable precision and accuracy were achieved, both intraday and interday for plasma and tissue homogenates. Thus, this newly developed procedure was successfully applicable for determination of nimodipine in mouse plasma and tissues following intravenous administration of free and novel niosome‐entrapped nimodipine.     

HPLC Determination of α-Amino Acids in Phytoplanktonic Marine Cells

Abstract

A procedure for the quantitative determination of 17 amino acids in a marine matrix using HPLC is reported. Pre-column derivatization with o-phthalaldehyde, separation on C₁₈-bonded silica with phosphate buffer (pH 7.2)-acetonitrile as eluent and fluorescence detection have been used. The good variation coefficient (average 2% with working curves in real matrix) and the low detection limit (1-5 fmoles) make the procedure suitable for the determination of total or free amino acids in matrix cultures.     

Solid Phase Extraction and HPLC Analysis of Tryptamide in Plasma

Abstract

A method for extraction and quantification of tryptamide in plasma is described in this report. The method employs Amberlite XAD-2 column extraction followed by HPLC with ultraviolet detection. The procedure is simple, rapid and reproducible. It has been applied to the measurement of tryptamide in plasma of rats dosed orally with this antiinflammatory and analgesic compound.     

A novel approach to determination of carbonyl groups in DMAc/LiCl-insoluble pulps by fluorescence labeling

The CCOA method for profiling of carbonyl groups by fluorescence labeling has meanwhile become an established procedure for dissolving pulps and rag papers. High molecular weight pulps, such as certain paper pulps, could not be analyzed so far due to their limited solubility in DMAc/LiCl. The new approach presented in this paper is based on the heterogeneous carbonyl-selective fluorescence labeling with CCOA (2), which is subsequently released with triflic acid from the labeled pulp in a quantitative manner, and the concentration of CCOA and CCOA-derived products is determined by HPLC. The procedure requires material in the mg range only. Calibration was performed against DMAc/LiCl-soluble standard pulps. Comparison of the data obtained by the novel approach correlated well with data from the established CCOA procedure.     

Determination of Ketoconazole in Plasma and Dosage Forms by High-Performance Liquid Chromatography and a Microbiological Method

Abstract

A simple and rapid high-performance liquid chromatographic (HPLC) method for the determination of ketoconazole in plasma and in tablets was developed. the method employs benzafibrate as internal standard and is sufficiently rapid and sensitive for use in pharmacokinetic studies. Separation of the drug from plasma was achieved by extraction with acetonitrile followed by a reversed phase chromatography on a μ Bondapak column using the isocratic mobile phase of methanol-water-glacial acetic acid (67.5:32:0.5). With this eluting solvent ketoconazole and the internal standard. were well separated from the components of plasma. A linear relationship was obtained between the ratio of the area under the peak of drug to that of the internal standard versus the concentration of the drug. Data comparing the microbiological assay with the HPLC procedure, which was developed, are shown. In the microbiological assay, Candida albicans, was the test organism, using the agar diffusion technique. Both methods were applied to the assay of ketoconazole in plasma and in tablets. Excellent agreement was observed between the results from the two methods.     

The Application of UV-Radioactivity High Performance Liquid Chromatography to the Study of Hypoxanthine Transport in Human Erythrocytes

Abstract

A procedure is presented for the simultaneous measurement of concentrations of labeled and non labeled hypoxanthine by HPLC in order to study hypoxanthine transport in erythrocytes. A radioactivity detector connected on-line to the high performance liquid chromatograph in series with a UV detector provides on-line quantitative monitoring of hypoxanthine in erythrocytes or incubation medium. The procedure provides a rapid, sensitive and convenient means for the study of hypoxanthine transport.     

High Pressure Liquid Chromatographic Determination of Isoniazid and Acetylisoniazid in Human Plasma

Abstract

A quantitative high pressure liquid chromatographic (HPLC) assay has been developed for the determination of isoniazid (INH) and acetylisoniazid (ACINH) in human plasma. Plasma samples were taken from a patient after oral administration of INH (with proven tuberculosis infection). A C₁₈ reversed phase radial compression column was used to separate INH and ACINH from other plasma components. The analysis takes 10 minutes per sample and the lower limit of detection for each compound is 0.10 ug/ml plasma.     

High Performance Liquid Chromatographic Assay of Hydromorphone Hydrochloride Injection

Abstract

A stability indicating high performance liquid chromatographic (HPLC) method for determining hydromorphone hydrochloride in dosage forms is described. The drug was chromatographed on a C₁₈ reverse phase column, using a mobile phase consisting of sodium lauryl sulfate, acetic acid, acetonitrile and water, and detected at 280 nm. Linearity of detector response to the concentration was confirmed. The procedure showed excellent reproducibility and gave quantitative recoveries of the drug from spiked placebos. Photodegraded samples of the dosage form, were assayed by the HPLC procedure and the current USP spectrophotometric procedure. Comparison of the results showed that the USP procedure is only partially stability indicating.     

Determination of Ascorbic Acid and Dehydroascorbic Acid in Blood Plasma Samples

Abstract

Following the stabilization of the plasma samples with HClO₄ and EDTA, the samples could be directly analyzed by HPLC using electrochemical detection and reversed-phase columns. The accuracy and precision of the method was evaluated using plasma samples spiked with ascorbic acid (10 μg/ml) and the results were also compared to the classical colorimetric procedure. Dehydroascorbic (5 μg/ml) was determined in plasma samples using UV detection following derivatization at room temperature for 45 minutes with o-phenylenediamine.     

Ion Exchanger Liquid Chromatography of N-Acetylaspartic Acid and Some N-Acetylaspartyl Peptides

Abstract

A high performance liquid chromatographic (HPLC) procedure for the rapid separation of N-acetylaspartic acid, N-acetyl-aspartyl-glutamic acid and N-acetylaspartyl-glutamyl-aspartic acid is described. The procedure utilizes a pellicular ion-exchange column support, and ionic strength gradient with mobile phase solutions buffered to pH 5.0 and a UV detector operated at 210 nm. Reproducibility and quantitative capabilities are also discussed. The method has been used for a tentative estimation of N-acetylaspartic acid and N-acetylaspartyl peptides in a rat brain synaptosomal extract.     

Application of Flow Programming in the Analysis of Drugs and Their Metabolites in Biological Fluids

Abstract

An HPLC procedure using flow programming under isocratic elution conditions for determination of drugs and their metabolites in biological fluids is discussed. This technique was used in the analysis of triamterene and its metabolites in urine, chlorothiazide in plasma and hydrochlorothiazide in urine. Advantages of flow programming over conventional procedures such as isocratic elution and gradient elution are discussed.