Showing papers on "Derivatization published in 1987"
TL;DR: High-performance liquid chromatography (HPLC) provides a rapid, sensitive, and reproducible means of separating and quantifying simultaneously a variety of sulfur-containing amino acids and related derivatives.
Abstract: Publisher Summary High-performance liquid chromatography (HPLC) provides a rapid, sensitive, and reproducible means of separating and quantifying simultaneously a variety of sulfur-containing amino acids and related derivatives. The HPLC method described in this chapter is modified and is based on the initial formation of S-carboxy-methyl derivatives of free thiols followed by the conversion of free amino groups to 2,4-dinitrophenyl (DNP) derivatives. Following derivatization, nanomole levels of individual sulfur-containing amino acids are measured using UV detection at 365 nm after separation by reverse-phase ion-exchange HPLC. Because of the versatility of this HPLC method, biological specimen preparation as well as derivatization and HPLC analysis procedures are discussed. DNP derivatives of acidic amino acids (including thiol-containing compounds) are separated on a 3-aminopropyl column by reversed-phase ion-exchange HPLC. In the mobile phase, methanol is used to elute rapidly the excess 2,4-dinitrophenol and the DNP derivatives of basic and neutral amino acids. Acetic acid is present in the mobile phase to maintain the bonded-phase amino groups in the protonated form. By increasing the sodium acetate concentration of the mobile phase, selective elution of acidic DNP derivatives is accomplished. The eluted DNP derivatives are measured by detection at 365 nm.
524 citations
TL;DR: In this article, the iodine-catalysed addition of dimethyl disulphide to linear alkenes leads smoothly to α,β-bis(methylthio)alkanes.
218 citations
TL;DR: The derivatization of cellulose in mixtures of lithium chloride and N, N -dimethylacetamide (LiCl/DMAc) is described in this paper, where a wide range of derivatives, including cellulose esters, carbamates, sulphonates, and ethers, have been synthesized in homogeneous solution using the LiCl/dMAc solvent.
173 citations
TL;DR: In this paper, a chiral recognition column with conjugated ovomucoid as the ligand was developed for chiral resolution of acids as well as amines without derivatization.
Abstract: A new chiral recognition column, with conjugated ovomucoid as the ligand, was developed. This column may be employed for the chiral resolution of acids as well as amines without derivatization. The retention time, capacity factor and resolution factor were dependent on pH, buffer strength and 2-propanol concentration of the mobile phase. For chlorpheniramine, a resolution factor of 1.5 was obtained.
154 citations
TL;DR: Most of the enantiomeric compounds showed good resolution with each of the three chiral mercaptans, whereas some enantiomers were only separable by one or two of them, and the method was applied to the analysis of peptide hydrolysates.
150 citations
TL;DR: The TBDMS derivatives possess very characteristic EI mass spectra at 70 eV, with intense diagnostic ions, which makes them very appropriate for GC-mass spectrometric (MS) work and selected ion monitoring GC-MS at the picomole level.
150 citations
TL;DR: A chiral phase HPLC method was developed for the simultaneous determination of the positional and optical isomers of the lipoxygenase-derived hydroxypolyenoic fatty acids and proved to be simpler and more sensitive.
129 citations
TL;DR: application of a resonance energy transfer assay to determine the transbilayer distribution of 7-nitro-2,1,3-benzoxadiazol-4-yl (NBD)-labeled lipid analogues in human red blood cells (RBC) showed that exogenously supplied NBD-phosphatidylserine (N BD-PS) was selectively transported to the inner leaflet, whereas NBD
Abstract: This report describes the application of a resonance energy transfer assay to determine the transbilayer distribution of 7-nitro-2,1,3-benzoxadiazol-4-yl (NBD)-labeled lipid analogues. The validity of this technique was established by determining the relationship between the distance of separation of lissamine rhodamine B labeled phosphatidylethanolamine (N-Rho-PE) acceptor lipid and NBD-labeled donor lipid and energy transfer efficiency. By determination of the distance between probes at 50% transfer efficiency (R0), the distance between fluorophores distributed symmetrically (outer leaflet label) and asymmetrically in artificially generated vesicles was determined. Calculation of the average distance between probes revealed a 14-A difference between NBD-lipid and N-Rho-PE localized in the same leaflet and in opposing leaflets, respectively. Application of this technique to the study of the transbilayer distribution of NBD-lipid in human red blood cells (RBC) showed that exogenously supplied NBD-phosphatidylserine (NBD-PS) was selectively transported to the inner leaflet, whereas NBD-phosphatidylcholine remained in the outer leaflet. In contrast, pretreatment of the RBC with diamide (a SH cross-linking reagent) blocked the transport of NBD-PS. The absence or presence of NBD-PS in the outer leaflet was independently verified by employing "back-exchange", trinitrobenzenesulfonic acid derivatization, and decarboxylation with PS decarboxylase experiments. These control experiments yielded results which confirmed the lipid distributions determined by the resonance energy transfer assay.
106 citations
TL;DR: In this article, a pre-column derivatization of amino acids in conifer extracts to form 9-fluorenylmethyl formate (FMOC) esters and the subsequent reversed phase high-performance liquid chromatography (HPLC) analysis of these esters have been investigated.
101 citations
TL;DR: Conditions are described for the efficient resolution by reversed-phase high-performance liquid chromatography on octadecylsilica stationary phases of individual molecular species of phosphatidylcholine on the basis of their fatty acyl composition.
84 citations
TL;DR: In this article, three methods of reductive amination have been investigated for the derivatization of aldehydes and ketones with a new chemiluminescent agent, 3-aminofluoranthene.
TL;DR: Succinimido alpha-naphthylcarbamate, an activated carbamate reagent, facilitated the simple and rapid pre-column derivatization of amino acids for fluorimetric detection using naphthylamine, which is more strongly retained than any amino acid derivatives.
TL;DR: An analytical method for the detection and quantification of ciprofloxacin and its known metabolites M1, M2, M3 and M4 in urine, serum/plasma, bile, faeces and tissue is described.
TL;DR: An easy and rapid method involving derivatization was developed for low concentration analysis of aliphatic amines (primary amines, secondary amines and polyamines) in air.
Abstract: An easy and rapid method involving derivatization was developed for low concentration analysis of aliphatic amines (primary amines, secondary amines, and polyamines) in air. Sampling was effected with silica gel tubes. The desorption of the collected amines was performed simultaneously with the derivatization. The resulting m-toluoyl derivatives were directly analyzed by high-performance liquid chromatography (HPLC) without an extraction procedure. Analyses were performed by use of a reversed-phase chromatography system with ultraviolet detection.
TL;DR: By this method, 5-10 ng of the standard trichothecenes could be determined by employing a clean-up procedure with a florisil column and a Sep-Pak CN cartridge.
TL;DR: Thermospray high-performance liquid chromatography-mass spectrometry (HPLC-MS) offers the sensitivity, specificity, and structural information to detect and identify some mycotoxin metabolites in fecal and urine samples without derivatization.
TL;DR: Using 3-tosylCholic, 3-benzoylcholic, and 3-iodocholic acids, in situ liver absorption, biliary excretion, and intestinal absorption studies in the rat were successful in establishing the concept that C3-derivatives and analogs of bile acids are, potentially, novel molecular delivery systems for intestinal and liver-site directed absorption.
Abstract: On the basis of the enterohepatocycling phenomenon of bile acids involving the intestines, liver, and gallbladder, it was conceptualized that bile acids could serve as a molecular carrier of drugs by taking advantage of the bile acid active transport mechanism. It was further proposed that derivatization or analogation of bile acids at the C3-OH position was the desired route because of the reactive hydroxyl group and, moreover, because of the active transport requirement of retaining the C17 side chain with a single terminal acidic function. Using 3-tosylcholic, 3-benzoylcholic, and 3-iodocholic acids, in situ liver absorption, biliary excretion, and intestinal absorption studies in the rat were successful in establishing the concept that C3-derivatives and analogs of bile acids are, potentially, novel molecular delivery systems for intestinal and liver-site directed absorption.
1 Jan 1987
TL;DR: In this article, a set of 3 volumes are presented, including a comparison of short-time, high-temperature hydrolysis with conventional 6 N HCl hydrolyse.
Abstract: The partial content of this set of 3 volumes include the following: sample preparation and protein hydrolysis; comparison of short-time, high-temperature hydrolysis with conventional 6 N HCl hydrolysis; development of the N-TFA n-butyl ester method; derivatization, separation and applications of the N-heptafluorobutyryl isobutyl derivatives; measurement of amino acids in fishery products; gas chromatography of the N-TFA amyl and methyl esters; electron capture, alkali flame, and flame ionization detection of the N-HFB isobutyl derivatives in blood plasma and other biological samples; screening for potential inborn errors of metabolism using the N-TFA n-propyl derivatives; the role of gas chromatography in the study of cosmochemistry; the chiral diamide phases for resolution of amino acid enantiomers, the influence of structural features of the diamides, mechanism of resolution of enantiomers, and enantiomeric analyses; analysis of amino acid racemization, the separation of amino acid enantiomers; the comparison of the resolution of various D,L-amino acid derivatives on optically active columns and age dating of sediments by determination of the extent of racemization of amino acids in fossil shells.
TL;DR: A reliable high-performance liquid chromatographic method that utilizes a reversed-phase separation with ion-pairing and post-column fluorescence derivatization for the analysis of N tau-methylhistidine in food, chicken excreta, and rat urine is described.
Abstract: A reliable high-performance liquid chromatographic method that utilizes a reversed-phase separation with ion-pairing and postcolumn fluorescence derivatization for the analysis of Nτ-methylhistidine in food, chicken excreta, and rat urine is described. Nτ-Methylhistidine in the hydrolyzed sample is first roughly separated from acid and neutral amino acids by an ion-exchange column. The Nτ-methylhistidine fraction is then evaporated and the residue is dissolved in the mobile phase (15mM sodium octane sulfonate in 20mM potassium phosphate), and subjected to high-performance liquid chromatography.
TL;DR: A sensitive and rapid method for the determination of ambroxol in biological fluids is described, which comprises a single extraction step, derivatization and selective determination with capillary gas-liquid chromatography (in split-mode) and electron-capture detection.
TL;DR: The conditions under which glycolipids with close chromatographic mobilities are coeluted and cannot be separated by a simple application of high-performance liquid chromatography are described.
Abstract: Publisher Summary High-performance liquid chromatography (HPLC) has been extensively utilized in separation of a number of glycosphingolipids. The quantity of the glycolipid mixture to be separated, the size of the column, the conditions of elution, particularly the composition and slope of gradient elution, and the speed of elution can be varied from one case to another. This chapter describes the general rules of the method applied for separation of different types of glycolipids by modifications of this method. However, glycolipids with close chromatographic mobilities are coeluted and cannot be separated by a simple application of this method. The conditions under which these components can be separated as acetylated derivatives are also described in the chapter. One procedure for the separation of different types of glycolipids is the separation of underivatized glycolipids by high-performance liquid chromatography. Intact glycosphingolipids without derivatization can be readily separated by HPLC with elution by gradient solvents composed of isopropanol–hexane–water in various ratios.
TL;DR: In this article, reversed-phase high-pressure liquid chromatography was used to determine histamine in trichloroacetic acid extracts after derivatization with o-phthaladehyde.
Abstract: Histamine was determined by reversed-phase high-pressure liquid chromatography in trichloroacetic acid extracts after derivatization with o-phthaladehyde. Fluorescence was monitored at 350 nm excitation and 450 nm emission wavelength after elution with water containing 40% acetonitrile. The advantage of the described method is a rapid analysis in an automated system, where no selective extraction procedure is necessary and interfering substances are easily separated from the histamine fluorophore.
TL;DR: In this article, a method for the separation and determination of neutral sugars as 2,4-dinitrophenyl derivatives is presented, which can be applied directly to unfractionated acid hydrolysate residues of glycoconjugates.
TL;DR: Specific environmentally significant arsenic compounds are determined by capillary gas-liquid chromatography by measuring inorganic and organic arsenicals as the corresponding methylthioglycolate derivatives.
Abstract: Specific environmentally significant arsenic compounds are determined by capillary gas-liquid chromatography. Inorganic (arsenite, arsenate) and organic (monomethylarsonate, dimethylarsinate) arsenicals are measured as the corresponding methylthioglycolate derivatives, which are simultaneously separated on wide-bore borosilicate glass and fused-silica columns under conditions of temperature programming. Inorganic arsenate and arsenite cannot be differentiated by the derivatization technique. Flame-ionization and electron-capture detection are evaluated. A simple and rapid sample preparation procedure is used for water, urine, blood, and tissue.
TL;DR: A highly efficient separation and purification procedure prior to the derivatization sequence allows quantification of the arachidonic acid metabolites described in two GC/MS runs, with the detection limit in the femtomole range.
Abstract: A method for measurement of PGF2 alpha, PGE1, PGE2, 6-keto-PGF1 alpha, TXB2, 2,3-dinor-TXB2 as well as 5-, 8-, 9-, 11-, 12-, 15-HETE and HHT, utilizing negative ion chemical ionization GC/MS is presented. A highly efficient separation and purification procedure prior to the derivatization sequence allows quantification of the arachidonic acid metabolites described in two GC/MS runs. The detection limit was in the femtomole range. Application of the method to the quantitative profiling of arachidonic acid metabolites in various tissues and incubation media is demonstrated.
TL;DR: The high performance liquid chromatographic method developed for the determination of aliphatic thiol drugs, such as N-acetyl-L-cysteine, captopril and mercaptopropionylglycine in pharmaceutical formulations, proved to be suitable for a reliable and selective quality control of commercial dosage forms of the examined thiol Drugs.
Abstract: A high performance liquid chromatographic method has been developed for the determination of aliphatic thiol drugs, such as N-acetyl-L-cysteine, captopril and mercaptopropionylglycine in pharmaceutical formulations. The procedure involves a precolumn derivatization of the thiol drug with ethacrynic acid followed by reversedphase HPLC separation and UV detection. The conditions for a rapid and selective reaction of the thiols with ethacrynic acid have been investigated. The method proved to be suitable for a reliable and selective quality control of commercial dosage forms of the examined thiol drugs.