Search results for "liquid"
showing 10 items of 4351 documents
L'absence de revendication n'interdit pas au tiers qui se prétend propriétaire d'un bien saisi entre les mains du débiteur d'en demander la distracti…
2003
International audience; (Com. 26 nov. 2002, Sebert c/ Sté Heuvellands Vleesbedrijf, pourvoi n° 01-03.980, arrêt n° 1960 FS-P)
Isocratic and gradient elution in micellar liquid chromatography with Brij-35
2015
Polyoxyethylene(23)lauryl ether (known as Brij-35) is a nonionic surfactant, which has been considered as an alternative to the extensively used in micellar liquid chromatography anionic surfactant sodium lauryl (dodecyl) sulfate, for the analysis of drugs and other types of compounds. Brij-35 is the most suitable nonionic surfactant for micellar liquid chromatography, owing to its commercial availability, low cost, low toxicity, high cloud temperature, and low background absorbance. However, it has had minor use. In this work, we gather and discuss some results obtained in our laboratory with several β-blockers, sulfonamides, and flavonoids, concerning the use of Brij-35 as mobile phase mo…
Micellar liquid chromatography for prediction of drug transport.
2000
Abstract The vast majority of well absorbed drugs are transported passively across the cell membranes. Physicochemical descriptors of drug molecules that are believed to influence transcellular transport are routinely used to predict drug absorption by means of complex mathematical models. In this paper, a new in vitro method, based on the retention data in micellar liquid chromatography (MLC), is validated for the prediction of passive drug absorption. The retention of a heterogeneous drugs set in MLC using Brij 35 as surfactant in the mobile phase is compared with the retention data reported in literature obtained in red cell membrane lipid liposomes, human red cell membranes vesicles (ve…
Influence of gamma-aminobutyric acid on baclofen intestinal absorption.
1994
Since previous studies suggested that baclofen absorption in the rat middle intestine was inhibited by beta-alanine and therefore mediated, at least in part, by the beta-aminoacid carrier, we focused our new studies on the analysis of the possible inhibition of the drug by a gamma-aminoacid model compound, gamma-aminobutyric acid (GABA). A rat jejunum in situ study was undertaken in order to evaluate the effect of GABA on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen with starting GABA concentrations ranging from 0 to 100 mM are reported. The results show that the absorption rate pseudoconstants of the drug decrease a…
Intestinal absorption pathway of gamma-aminobutyric acid in rat small intestine.
1994
Intestinal absorption of gamma-aminobutyric acid (GABA), as a model compound for gamma-aminoacids, has not been extensively studied from the kinetic viewpoint. Since data from our laboratory suggested that some competition arises between intestinal absorption of beta-alanine and GABA and since our intent was to maintain the aqueous stagnant diffusion layer in order to approach absorption tests to in vivo physiological conditions, a rat jejunum in situ study was undertaken in order to gain an insight into the mechanism of GABA absorption. In the present paper, results from assays using isotonic perfusion solutions with starting GABA concentrations ranging from 1 to 50 mM are reported. They s…
Comparison of novel and conventional calibration techniques for the analysis of urine samples using plasma source mass spectrometry combined with a n…
2012
The accuracy and precision of the analytical data from the analysis of liquid samples with high matrix load often suffer from a compromised performance of the sample introduction system. This is especially significant in the case of miniaturized, pneumatic low flow nebulizers. Alternative low-flow sampling devices based on different operating principles are imperative to overcome this drawback. The superior performance of such an alternative liquid sample introduction system for ICP-MS, the drop-on-demand (DOD) aerosol generator based on thermal inkjet technology, was recently outlined by the same group for the analysis of aqueous standard solutions. Current improvements of the system now a…
Fluorimetric determination of amphetamine in urine by flow injection with on-line liquid–liquid extraction
2001
Abstract Determination of amphetamine in urine was performed by batch and flow injection methodologies. The suitable experimental conditions for fluorimetric measurements were established. The liquid–liquid extraction was carried out at pH 13 using diethyl ether as extracting reagent. The measurement conditions were 260 nm and 277 nm for excitation and emission wavelengths, respectively. The method requires standard addition calibration and Youden blank correction. The influence of the main metabolites of amphetamine and metamphetamine were studied. The accuracy and precision of the proposed method was tested and the method is adapted to the flow injection procedure with on-line extraction.
Development of microextraction techniques in combination with GC-MS/MS for the determination of mycotoxins and metabolites in human urine.
2017
Simple and highly efficient sample preparation procedures, namely, dispersive liquid–liquid microextraction and salting-out liquid–liquid extraction for the analysis of ten Fusarium mycotoxins and metabolites in human urine were compared. Various parameters affecting extraction efficiency were carefully evaluated. Under optimal extraction conditions, salting-out liquid–liquid extraction showed a better accuracy (84–96%) and precision (<14%) than dispersive liquid–liquid microextraction. Hence, a multibiomarker method based on salting-out liquid–liquid extraction followed by gas chromatography with tandem mass spectrometry was proposed. Satisfactory results in terms of validation were achiev…
Quantitative evaluation of the phenolic profile in fruits of six avocado (Persea americana) cultivars by ultra-high-performance liquid chromatography…
2016
The phenolic profiles of six varieties of avocado (Persea americana) grown in Sicily were investigated. The ultra-high-performance liquid chromatography-heated electrospray-mass spectrometry method was developed to determine qualitative and quantitative changes in fruits at two different ripening stage. Nineteen individual phenolic compounds were detected in avocado pulp extracts. Gallic acid, sinapinic acid, vanillin, p-coumaric acid, and gentisic acid were present only in ripe fruits. On the contrary, epicatechin decreased with fruit ripening, whereas protocatechuic acid, 4-hydroxybenzoic acid, chlorogenic acid, and benzoic acid were relatively stable or exhibited erratic changes with fru…
Isocratic high-performance liquid chromatographic determination of tryptophan in infant formulas.
1996
The application to infant formulas of a method for tryptophan determination by isocratic HPLC with UV detection at 254 nm, after derivatization with phenyl isothiocyanate, was studied. Protein was hydrolysed by barium hydroxide at 120 degrees C for 8 h, followed by derivatization with phenyl isothiocyanate, HPLC and UV detection at 254 nm. The optimum chromatographic conditions (pH, ionic strength of elution solvent and eluent ratio) were established. The analytical parameters (linearity, precision, accuracy of derivatization and limits of detection and quantification) were determined. The values obtained demonstrated that the method is useful for determining the tryptophan content of infan…