Liquid chromatography and radioimmunoassay compared for determination of cortisol and corticosterone in plasma after a dexamethasone suppression test.

1987 ◽  
Vol 33 (9) ◽  
pp. 1639-1642 ◽  
Author(s):  
K Oka ◽  
M Noguchi ◽  
T Kitamura ◽  
S Shima
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Internal Standard ◽  
Solvent System ◽  
Peak Height ◽  
Peak Height Ratio ◽  
Analytical Recovery ◽  
Suppression Test ◽  
Dexamethasone Suppression

Abstract We developed sensitive, specific "high-performance" liquid chromatography (HPLC) for determining suppressed cortisol and corticosterone in human plasma and compared its efficacy with that of conventional radioimmunoassay (RIA) at concentrations in the nanogram per liter range. Steroids from a 0.5-mL aliquot of plasma were extracted by rapid-flow fractionation, with diethyl ether as mobile-phase solvent, diatomaceous earth granules as stationary-support material. Analytical recovery of the steroids approached 100%. Concentrations in plasma were determined from peak-height ratio calibration (dexamethasone internal standard). The analytical column contained silica gel and the solvent system was water/methanol/dichloromethane/n-hexane (0.1/3/30/66.9 by vol). We could measure the steroids before and 20 h after oral administration of 0.5 mg of dexamethasone. The detection limit was 300 ng per liter of plasma for corticosterone, 500 ng/L for cortisol, with CVs of less than 4%. Determining corticosterone after administration of dexamethasone, in four of 20 such samples we could determine concentrations greater than 300 ng/L; the others contained corticosterone between 100 and 300 ng/L, but these values could not be certified analytically. Mean concentrations of these hormones as determined by RIA substantially exceeded those by HPLC. Some cross reactions in RIA could not be considered negligible in spite of pre-column treatment of the extracts.

Beta-carotene determined in serum by liquid chromatography with an internal standard.

1983 ◽  
Vol 29 (6) ◽  
pp. 1042-1044 ◽  
Author(s):  
W J Driskell ◽  
M M Bashor ◽  
J W Neese
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Methylene Chloride ◽  
Internal Standard ◽  
Beta Carotene ◽  
Solvent System ◽  
Peak Height ◽  
Reversed Phase ◽  
Human Populations ◽  
Relationship Of

Abstract We describe a procedure for quantitative determination of beta-carotene in human serum. The 0.1-mL serum sample is precipitated with ethanol containing the internal standard, dimethyl-beta-carotene, then extracted with hexane. This extract is injected onto a reversed-phase, "high-performance" liquid-chromatography column, and the carotenes are resolved and eluted with an acetonitrile/methylene chloride isocratic solvent system. They are quantified from the peak-height ratios of their absorbance at 450 nm. About 14 min is required for each chromatogram. The procedure has excellent precision and is appropriate for routine use in analysis of large numbers of samples. The method should be particularly useful for clinical studies on the relationship of serum beta-carotene and cancer incidence in human populations.

Determination of azadirachtin by reversed-phase high-performance liquid chromatography using anisole as internal standard

1995 ◽  
Vol 705 (2) ◽  
pp. 374-379 ◽  
Author(s):  
R. Thejavathi ◽  
Shirish R. Yakkundi ◽  
B. Ravindranath
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Internal Standard ◽  
Reversed Phase

scholarly journals A Simple High-Performance Liquid Chromatography Method for Simultaneous Determination of Three Triazole Antifungals in Human Plasma

2012 ◽  
Vol 57 (1) ◽  
pp. 484-489 ◽  
Author(s):  
Mei Zhang ◽  
Grant A. Moore ◽  
Murray L. Barclay ◽  
Evan J. Begg
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Simultaneous Determination ◽  
Human Plasma ◽  
High Performance ◽  
Internal Standard ◽  
Gradient Elution ◽  
Limit Of Quantification ◽  
Chromatography Method

ABSTRACTA rapid and simple high-performance liquid chromatography (HPLC) assay was developed for the simultaneous determination of three triazole antifungals (voriconazole, posaconazole, and itraconazole and the metabolite of itraconazole, hydroxyitraconazole) in human plasma. Sample preparation involved a simple one-step protein precipitation with 1.0 M perchloric acid and methanol. After centrifugation, the supernatant was injected directly into the HPLC system. Voriconazole, posaconazole, itraconazole, its metabolite hydroxyitraconazole, and the internal standard naproxen were resolved on a C6-phenyl column using gradient elution of 0.01 M phosphate buffer, pH 3.5, and acetonitrile and detected with UV detection at 262 nm. Standard curves were linear over the concentration range of 0.05 to 10 mg/liter (r2> 0.99). Bias was <8.0% from 0.05 to 10 mg/liter, intra- and interday coefficients of variation (imprecision) were <10%, and the limit of quantification was 0.05 mg/liter.

scholarly journals Quantification of ADMA: analytical approaches

2005 ◽  
Vol 10 (2_suppl) ◽  
pp. S89-S95 ◽  
Author(s):  
Edzard Schwedhelm
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Internal Standard ◽  
Exchange Chromatography ◽  
Absorbance Detection ◽  
Human Blood And Urine ◽  
Oxide Synthase ◽  
Analytical Approaches ◽  
Circulating Levels

Methylated L-arginine analogs are involved in nitric oxide synthase activity regulation. Methods based on high-performance liquid chromatography with fluorescence, capillary electrophoresis, or ion exchange chromatography with absorbance detection were first applied for the quantitative determination of N-monomethyl-L-arginine (NMMA), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) in human blood and urine. These assays revealed elevated circulating levels of ADMA in various diseases and gave accumulating evidence of the usefulness of ADMA as a cardiovascular risk factor. However, the methods used are hampered by the fact that NMMA, ADMA and SDMA can be distinguished from L-arginine only by means of chromatographic separation. This has promoted the development of alternatives that involve mass spectrometry (MS) technology. Today, various MS-based approaches such as liquid chromatography (LC)-MS, LC-MS/MS, gas chromatography (GC)-MS, and GC-MS/MS are available. L-arginine and its analogs have been subjected to LC-MS analysis with and without further derivatization to their o-phthaldialdehyde derivatives. For these methods, labelled L-arginine was used as the internal standard. The first MS-based method that distinguishes NMMA, ADMA, SDMA and L-arginine by mass-to-charge (m/z)- ratio has been reported by Tsikas et al. This GC-MS approach has been further improved by Albsmeier et al by introducing labelled ADMA as an internal standard. As an alternative to existing methods, a commercially available ELISA kit has recently been developed and validated.

scholarly journals Determination of metoprolol in pure and pharmaceutical dosage forms by spectrofluorometry and high performance liquid chromatography

2011 ◽  
Vol 17 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Bilal Yilmaz ◽  
Kadem Meral ◽  
Ali Asci ◽  
Yavuz Organer
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Solvent System ◽  
Dosage Forms ◽  
Content Uniformity ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
Limit Of Quantitation

In this study, a new and rapid spectrofluorometry and high performance liquid chromatography (HPLC) methods were developed for determination of metoprolol in pure and pharmaceutical dosage forms. The solvent system, wavelength of detection and chromatographic conditions were optimized in order to maximize the sensitivity of both the proposed methods. The linearity was established over the concentration range of 50-4000 ng ml-1 for spectrofluorometry and 5.0-300 ng ml-1 for HPLC methods. The intra- and inter-day relative standard deviation (RSD) was less than 4.14 and 3.86% for spectrofluorometry and HPLC, respectively. Limit of quantitation was determined as 30 and 5.0 ng ml-1 for spectrofluorometry and HPLC, respectively. No interference was found from tablet excipients at the selected assay conditions. The methods were applied for the quality control of commercial metoprolol dosage forms to quantify the drug and to check the formulation content uniformity.

Determination of β -Sitosterol with Chemical Course and Material Applications in Jatropha Seed Oil by High Performance Liquid Chromatography

2012 ◽  
Vol 577 ◽  
pp. 69-72 ◽  
Author(s):  
Shu Yu Liu ◽  
Anaerguli Maihemuti
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Seed Oil ◽  
Reversed Phase ◽  
Analytical Recovery ◽  
Relative Standard ◽  
The Mean ◽  
Jatropha Seed

A simple and rapid high performance liquid chromatography (HPLC) assay was developed to identify and measure theβ-sitosterol with chemical course and material applications in jatropha seed oil. The stigmasterol was isolated with a good selectivity by HPLC employing reversed phase C18 columns. The components were separated by mobile phase of methanol-water (99/1, v/v) and detected at 205nm. The quantitation of the stigmasterol was reproducible and the method relative standard deviation is 1.1%. The mean analytical recovery was 96.2%.

Determination of cocaine concentrations in plasma by high-performance liquid chromatography

1990 ◽  
Vol 36 (8) ◽  
pp. 1436-1439 ◽  
Author(s):  
P Jatlow ◽  
H Nadim
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Plasma Concentrations ◽  
Internal Standard ◽  
Reversed Phase ◽  
Dilute Acid ◽  
Nitrogen Detection ◽  
Chromatographic Procedure

Abstract We describe a procedure for measuring concentrations of cocaine in plasma by reversed-phase high-performance liquid chromatography, with ion-pairing. The procedure involves solvent extraction followed by back-extraction with dilute acid. The n-propyl ester of benzoylecgonine is used as an internal standard. An evaporation step is not required, and concentrations as low as 5 micrograms/L can be quantified. Plasma concentrations of cocaine determined by high-performance liquid chromatography correlated well with those determined by a previously reported gas-chromatographic procedure with nitrogen detection.

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