Use Of High-pressure Liquid Chromatography Research Articles

Use of high-pressure liquid chromatography to determine plasma levels of metronidazole and metabolites after intravenous administration.

A rapid and sensitive high-pressure liquid chromatography assay for metronidazole and its two principle metabolites, 1-(2-hydroxyethyl-2-hydroxymethyl)-5-nitro-imidazole [hydroxy metabolite] and 1-acetic acid-2-methyl-5-metronidazole [acid metabolite], was developed. The retention times observed were 5.7, 3.3, and 4.5 min, respectively. A reverse-phase muC(18) Bondapak column using a solvent system of methanol, acetonitrile, and 0.005 M pH 4 potassium dihydrogen phosphate (4:3:93, vol/vol) was used to achieve separation of the three compounds. Patients receiving metronidazole therapy were given a loading dose of 13.6 mg of drug per kg intravenously over 1 h, followed by a maintenance dose of 1.43 mg/kg per h. The range of metronidazole concentrations observed was 6.8 to 47.5 mug/ml. These levels are well above the minimal inhibitory concentrations of most clinically significant anaerobic bacteria including Bacteroides fragilis. Little of the acid metabolite was observed in the plasma. The concentration of hydroxy metabolite ranged from 1.6 to 16 mug/ml. The latter may represent an additional source of antimicrobial activity since the hydroxy metabolite has approximately 30% the biological activity of metronidazole.

Electrophilic substitution in indoles. Part 10. The mechanism of substitution in 4,6- and 5,6-dimethoxyindoles

Deuterium-labelling experiments show that the boron trifluoride-catalysed cyclisation (at 80 °C) of 4-(4,6-dimethoxyindol-3-yl)butanol (3c) to 5,7-dimethoxytetrahydrocarbazole (9c) occurs by two simultaneous pathways. The main route (61.5%) involves initial cyclisation at the 3-position of (3c) to give an intermediate spirocyclic indole which then rearranges to the tetrahydrocarbazole; the minor pathway (38.5%) involves direct attack at the 2-position. The cyclisation of 4-(5,6-dimethoxyindol-3-yl)butanol (3d) to 6,7-dimethoxytetrahydrocarbazole (9d) also occurs by two routes, but in this case a much lower proportion (13.5%) arises by direct attack at the 2-position. Kinetic studies of the overall rates of cyclisation of the indolylbutanols (3) to tetrahydrocarbazoles (9) were facilitated by the use of high-pressure liquid chromatography, and showed that the relative rates were as follows: 4-indol-3-ylbutanol (3a) > 4-(6-methoxyindol-3-yl)butanol (3b) > 4-(4,6-dimethoxyindol-3-yl)butanol (3c) > 4-(5,6-dimethoxyindol-3-yl)butanol (3d). The differences in rates were tentatively attributed to the effects of the methoxy-groups on the rates of rearrangement of the protonated spirocyclic indole intermediates (5) formed by direct attack at the indole 3-position.

Use of high-pressure liquid chromatography in the assay of aldosterone in urine.

Use of high-pressure liquid chromatography in the assay of aldosterone in urine.

Isotopic separations of tritium-substituted compounds from protium analogues by high-pressure liquid chromatography

The use of high-pressure liquid chromatography (HPLC) for the separation of a large variety of compounds is now common. Those compounds which contain hydrophobic moieties can often be well separated on reverse phase columns where the stationary hydrocarbon phase is bound to the support and the compounds are eluted with water, mixed with polar organic solvents such as methanol. One of the advantages of HPLC is the high column efficiency which can be obtained. Despite this, however, it may still not be possible to resolve certain closely related compounds, such as the 12 phenols of benzo[ a]pyrene (BP) (1,2). Thus, when identity between a radioactive component and its unlabeled analogue is to be claimed, great care must be exercised. We were concerned, therefore, when, during an investigation (3) of products formed by the enzyme-catalysed binding of 7,12-[G- 3H]dimethylbenz[ a]anthracene (DMBA) to polyguanosine, some of the modified nucleoside adducts showed very slightly shorter retention times than the unlabelled compound to which it was thought they corresponded. the possibility that this was an isotopic separation (4) was investigated.

High-pressure liquid chromatographic analysis of amino acid phenylthiohydantoins: Comparison with other techniques

High-pressure liquid chromatography, utilizing reverse phase μ Bondapak C18 columns and elution with increasing acetonitrile concentrations, has been used to resolve amino acid phenylthiohydantoins obtained from the automated Edman degradation of proteins. Assignment of identity to residues which are difficult to distinguish or identify conclusively by other conventional techniques is easily achieved by high-pressure liquid chromatographic techniques. The use of high-pressure liquid chromatography, in parallel with gas-liquid and polyamide thin-layer chromatography, allows unequivocal assignments of identity to amino acid phenylthiohydantoins obtained in protein sequencing. Single protein sequence determinations can be extended by 20 to 100% by the use of high-pressure liquid chromatography with rapid, accurate, and quantitative identifications of amino acid phenylthiohydantoins.

Use of high-pressure liquid chromatography for quantitative structure-activity relationship studies of sulfonamides and barbiturates

Retention volumes for a group of sulfonamides obtained on three different HPLC columns were correlated with log P, pKa, and biological activity. Depending on the chromatographic system, good correlations can be obtained with log P or with biological activity, but not necessarily both, using the same chromatographic data.

Identification and quantification of juvenile hormones from different developmental stages of the cockroach [formula omitted][formula omitted

By the combined use of high-pressure liquid chromatography, Galleria bioassay and gas chromatography/ chemical ionization/mass spectrometry we were able to isolate and identify the three known natural juvenile hormones (JHs) from haemolymph extracts of larval and adult females of the cockroach Nauphoeta cinerea . This is the first demonstration of the simultaneous occurrence of the three JHs in the same insect and the first time JH I and II have been identified in a hemimetabolous insect. Quantitative investigations show that the composition of the three JHs is different at different developmental stages. The haemolymph of larvae contains a high percentage of JH I and II, whereas the haemolymph of adult females in the oocyte maturation stage contains mostly JH III. This suggests more juvenilizing functions for JH I and II and more gonadotropic functions for JH III.

Use of high-pressure liquid chromatography for the fractionation of less volatile flavor compounds

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUse of high-pressure liquid chromatography for the fractionation of less volatile flavor compoundsShu-Chi. Lee and Stephen S. ChangCite this: J. Agric. Food Chem. 1975, 23, 2, 337–339Publication Date (Print):March 1, 1975Publication History Published online1 May 2002Published inissue 1 March 1975https://doi.org/10.1021/jf60198a021RIGHTS & PERMISSIONSArticle Views24Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (343 KB) Get e-Alerts Get e-Alerts

Preliminary investigation of the use of high-pressure liquid chromatography for the separation of indole alkaloids

Preliminary investigation of the use of high-pressure liquid chromatography for the separation of indole alkaloids

Use of High-Pressure Liquid Chromatography for Monitoring Nucleotide Concentration in Human Blood: A Preliminary Study with Stored Blood Cell Suspensions

Abstract The development of high-pressure liquid chromatography has made available a new technique for monitoring nucleotide concentrations in biological materials sensitively, accurately, and rapidly. Because there appears to be a correlation between ATP concentrations and viability of stored blood, a preliminary study was carried out on blood cell suspensions to evaluate the technique for possible use in blood banks, clinical laboratories, and research on preservatives for blood.