Search results for "Deriva"
showing 10 items of 1423 documents
Determination of busulfan in human plasma using high-performance liquid chromatography with pre-column derivatization and fluorescence detection.
1999
A rapid, sensitive and reproducible high-performance liquid chromatographic assay for busulfan in human plasma was developed. After extraction of plasma samples with acetonitrile and methylene chloride, busulfan and the internal standard [1,5-bis(methanesulfonyloxy)pentane] were derivatized with 8-mercaptoquinoline to yield fluorescent compounds which were detected with a fluorescence detector equipped with filters of 360 nm (excitation) and 425 nm (emission). Calibration graphs showed a linear correlation (r>0.9990) over the concentration range of 20-2000 ng/ml. The recovery of busulfan from plasma standards was 70+/-5%. The detection and quantification limits for busulfan in plasma sample…
Photochemical derivatization and fluorimetric determination of reserpine in a flow-injection assembly
1991
Abstract The fluorimetric flow-injection determination of reserpine was achieved with the drug being derivatized on-line by photoreaction. PTFE tubing was helically coiled around a germicide lamp located between the injection valve and detector. Two analytical procedures are proposed using either dilute acetic acid or pure methanol as the carrier stream. The influence of foreign compounds was studied and the method was applied to the determination of reserpine in pharmaceutical formulations.
Liquid chromatographic determination of aliphatic amines in water using solid support assisted derivatization with 9-fluorenylmethyl chloroformate
2002
A simple and sensitive method has been developed for the liquid chromatographic determination of short-chain aliphatic amines in water. Analytes are retained in solid-phase extraction (SPE) cartridges, and then derivatized by drawing an aliquot of the fluorogeneic reagent 9-fluorenylmethyl chloroformate (FMOC) through the cartridges. After a certain reaction time the derivatives formed are desorbed with acetonitrile. The collected extracts are then chromatographed on a LiChrospher 100 RP18 125 mm×4 mm i.d., 5 μm, column using an acetonitrile-water gradient. The influence of experimental conditions (SPE material, volume of sample, concentration of FMOC, time of reaction and pH) has been inve…
Current methodologies for phytosterol analysis in foods
2021
Abstract Plant sterols (PS) (phytosterols and phytostanols) are bioactive compounds of all vegetable foods where can be found as free sterol alcohols and as conjugates. These latter forms have been less studied, although they may have potential beneficial effects, whereas some PS have several approved health claims, especially in lowering blood cholesterol levels. In this context, it is necessary to establish analytical methods for food authentication, assessing PS health benefits and unfolding future applications. Several extraction methodologies have been employed for the extraction of PS from food matrixes (usually solvent extraction and saponification) although solid-phase extraction, s…
Suppression of pigment interference in the gas chromatographic analysis of proteinaceous binding media in paintings with EDTA.
2004
A method to suppress the interference of pigments in the analysis of proteinaceous media used in paintings is presented in this paper. This method is based on the formation of metallic ion-ethylenediaminetetraacetic acid (EDTA) complexes previous to the derivatisation process, using ethyl chloroformate (ECF), to transform the amino acids in N(O,S)-ethoxycarbonyl (EOC) ethyl esters. Test specimens, containing different proteinaceous media such as albumin, porcine gelatine and casein mixed with lead white, chalk, verdigris and raw Sienna have been prepared for carrying out this study. Different pH conditions have been probed for the different pigments studied. Values of peak area ratio of ami…
Off-line dansylation of amines using C18 solid-phase packings: study of the fluorescence and chemiluminescence detection by post-column derivatizatio…
1999
Abstract Dansylation of amines (primaries and secondaries) using C18 solid-phase supports is described. The time of analysis and the handing sample have been markedly improved with respect to those required for solution dansylation. The dansylated amine derivates were injected onto the liquid chromatography system and fluorescence detected. The sensitivity and selectivity is better than the other dansylation procedures described in the literature and also better than other derivatization reagents such 1,2-napthoquinone 4-sulfonate (NQS) or 3,5-dinitrobenzoyl chloride (3,5-DNB). Dansyl compounds can also form chemiluminescent derivatives, therefore a post-column derivatization procedure with…
Method development for the determination of 1,1-dimethylhydrazine by the high-performance liquid chromatography-mass spectrometry technique.
2018
Unsymmetrical dimethyl hydrazine is highly toxic, carcinogenic compound, widely used for organic synthesis and drug development. Therefore, due to its high reactivity, direct analysis is problematic. Current study proposes to use derivatization reaction to increase selectivity and sensitivity of high-performance liquid chromatography–mass spectrometry method. Different derivatization agents were tested and optimal reaction media was found. Derivatization was performed by using small amounts of reagents to lower the cost of analysis. The full validation of the method was performed and it can be used in a routine control in pharmaceutical analysis. Method sensitivity is 0.15 ppm, and lineari…
Chromium(VI) oxide oxidation of non-ethoxylated and ethoxylated alcohols for determination by electrospray ionization mass spectrometry
2010
A new derivatization procedure to increase the sensitivity of electrospray ionization mass spectrometry (ESI-MS) to non-ethoxylated and ethoxylated alcohols was investigated. The analytes were oxidized with chromium(VI) oxide and the resulting carboxylic and ethoxy-carboxylic acids were isolated by extraction with ethyl acetate; the extracts were alkalinized and infused into the ESI-MS system working in the negative-ion mode. The yields of the combined oxidation-extraction were ca. 100% for non-ethoxylated fatty alcohols dissolved in acetone and they decreased moderately in samples containing increasing amounts of water (e.g., a 75% yield was obtained with 50% water). Ethoxylated alcohols w…
Detector supports: application to aliphatic amines in wastewater
2005
Abstract Solid support assisted derivatization coupled to diffuse reflectance spectroscopy (DRS) was proposed and proved useful for the detection and quantification of aliphatic amines in water as an example. Dabsyl chloride (DBS), ninhydrin and sodium 1,2-naphtoquinone 4-sulphonate (NQS) were assayed as derivatization reagents. C 18 and SDB-XC disks and C 18 cartridges were tested for amine retention and after that derivatization. The decrease of the orange colour of dabsyl chloride on SBD-XC disks produced by the formation of its derivative with methylamine in the support (10 min at 100 °C) allowed the selective determination of the amine at concentration level equal or higher than 0.5 mg…
Critical study of and improvements in chromatographic methods for the analysis of type B trichothecenes
2001
Various analytical methods used in the analysis of type B trichothecenes (deoxynivalenol, nivalenol, 3- and 15-acetyldeoxynivalenol) in cereals were compared and optimised in this work. These methods use either GC-electron-capture detection (ECD) of trimethylsilyl, trifluoroacetyl and heptafluorobutyryl derivatives or HPLC with UV or photodiode array detection of analytes. A new HPLC procedure using fluorescence detection prior derivatisation with coumarin-3-carbonyl chloride has been also tested. Five extraction solvents and two solid-phase extraction cartridges (silica, Florisil) plus a especial clean-up column (MycoSep 225) were compared in order to obtain the best recovery of the mycoto…