Search results for "liquid"
showing 10 items of 4351 documents
Determination of α-Tocopherol in Plasma by High Performance Liquid Chromatography with Fluorescence Detection and Stability of α-Tocopherol under Dif…
2011
In order to study the clinical effects of the antioxidant alpha-tocopherol (tocofersolan, CAS 30999-06-5) a simple, robust, sensitive and reliable high performance liquid chromatography (HPLC) method using fluorescence detection for the daily measurement of alpha-tocopherol concentration in plasma is described. Several methods of HPLC analysis using fluorescence techniques are published, however, investigations of the stability of alpha-tocopherol during sample preparation under different conditions are relevant in the routine measurements and have to date not been reported. Therefore a modified method, both sensitive and robust, qualified for the day-by-day measurement of alpha-tocopherol …
Towards the optimization of complementary systems in reversed-phase liquid chromatography
2002
Previously reported optimization methodology, which seeks complementary mobile phases (CMP) in isocratic chromatography, has been extended to include more than one system simultaneously (i.e. more than one organic solvent and/or column). In the literature the benefits of complementarity are not usually fully exploited—few working conditions giving rise to interactions as different as possible are examined, without developing a fully linked optimization. The proposed approach is compared critically with use of a single mobile phase or CMP which consider one system only. The strategy greatly expands the capability of isocratic chromatography in the analysis of complex samples that cannot be r…
Possible interferences of mercury sulfur compounds with ethylated and methylated mercury species using HPLC-ICP-MS
2002
The HPLC-ICP-MS coupling technique is able to separate and detect methyl, ethyl and inorganic mercury isotopes specifically. An identification of ethyl mercury(+) is not possible when the widely used sodium tetraethylborate derivatisation method in combination with GC-AFS/AAS or ICP-MS techniques is performed because it contains ethyl groups.An unidentified compound with the same retention time as ethyl mercury was found in the HPLC chromatograms of industrial sewage samples and humic-rich soils of microcosm experiments after applying water vapour distillation. We also observed such unidentified peaks in samples of heavily contaminated sites in Eastern Germany, separated by HPLC fractionati…
PEMBEKUAN SEMEN LELE DUMBO (Clarias Gariepinus BURCHELL 1822) SEBAGAI MODEL KRIOPRESERVASI SEMEN IKAN
2010
<p><em>Effect of four types of diluents</em><em>s</em><em> and four concentration of DMSO (5%, 10%, 15% and 20%) against the motility of African catfish sperm were evaluated after storage at freezing temperatures. </em><em>The steps in preparation the 16 treatments combination of the diluents</em><em> </em><em>are </em><em>preparation of diluents, mixing </em><em>diluents </em><em>with DMSO, packing </em><em>of semen </em><em>in</em><em>to</em><em> 0.3-ml straw, equilibration of </em><em>semen </em><em>at 4 °C for…
Molecular connectivity as a relevant new tool for predicting analytical behavior: A survey of chemiluminescence and chromatography
2005
Abstract We present a critical presentation and discussion on molecular connectivity applied to analytical fields, giving special attention to predicting the chemiluminescent behavior of pharmaceuticals and pesticides. Molecular connectivity has been largely applied to predict the therapeutic effects of pharmaceuticals and rarely to predictions in analytical chemistry – basically to chromatographic processes and recently to liquid-phase chemiluminescence.
Determination of Anticonvulsant Drugs in Pharmaceutical Preparations by Micellar Liquid Chromatography
2004
A micellar liquid chromatographic method for quality control of pharmaceutical preparations (capsules, pills, tablets, injections, drops, and suppositories) containing the anticonvulsant drugs acetazolamide, carbamacepine, chlordiazepoxide, diazepam, ethosuximide, phenytoin, phenobarbital, and zopiclone has been developed. This methodology involves the use of micellar solutions of cetyltrimethylammonium bromide (CTAB) as mobile phases and UV detection. The proposed approach is rapid and reproducible. Sample preparation only requires dissolution with micellar solvent and adequate dilution with the mobile phase before injection into the chromatographic system.
Estimation of diuretic drugs in biological fluids by HPLC
1992
This critical review of different methods proposed for the determination and screening of diuretics is directed mainly, because of its potential application, towards highperformance liquid chromatography.
A Study of Lipid-Lipid and Lipid-Polypeptide Interactions by High Performance Liquid Chromatography
1984
Abstract Ternary systems containing phosphatidylcholine-cholesterol, phosphatidylcholine-gramicidin A or cholesterol-gramicidin A in tetrahydrofuran have been examined by high performance liquid chromatography. Preferential solvation of cholesterol and especially gramicidin A by phosphatidylcholine is observed. These results are interpreted in terms of hydrophobic interactions between membrane components.
Ionic liquids in separation techniques.
2007
The growing interest in ionic liquids (ILs) has resulted in an exponentially increasing production of analytical applications. The potential of ILs in chemistry is related to their unique properties as non-molecular solvents: a negligible vapor pressure associated to a high thermal stability. ILs found uses in different sub-disciplines of analytical chemistry. After drawing a rapid picture of the physicochemical properties of selected ILs, this review focuses on their use in separation techniques: gas chromatography (GC), liquid chromatography (LC) and electrophoretic methods (CE). In LC and CE, ILs are not used as pure solvents, but rather diluted in aqueous solutions. In this situation IL…
Improved sample preparation for the testosterone hydroxylation assay using disposable extraction columns
1992
The preparation of samples for injection into a high-performance liquid chromatograph from assay mixtures for the determination of cytochrome P-450-dependent testosterone hydroxylation has been substantially facilitated. By replacing the multiple cumbersome extraction steps of the conventional method with a single column extraction the time for sample preparation was reduced from hours to minutes. The new procedure also yields better recoveries for most of the testosterone metabolites than the original protocol. The use of extraction columns for sample preparation allows the simultaneous treatment of a large number of samples or even the automation of the whole assay procedure. The modified…