Showing papers on "Derivatization published in 1980"
198 citations
TL;DR: In this article, a method for reversed-phase high-performance liquid chromatographic resolution of amino acid enantiomers by the formation of diastereomers using a new chiral reagent, 2,3,46-tetra-O-acetyl-β- d -glucopyranosyl isothiocyanate (GITC), is described.
184 citations
143 citations
TL;DR: In this paper, 9-Diazomethylanthracene reacts with carboxyl groups to give an ester derivative which can be used as either a fluorescence or ultraviolet label for fatty acid analysis by high-pressure liquid chromatography.
140 citations
TL;DR: In this article, an ion exchange/derivatization procedure is described for the determination of C_1-C_5 volatile fatty acids in a range of difficult aqueous matrices.
Abstract: An Ion-exchange/derivatization procedure is described for the determination of C_1-C_5 volatile fatty acids in a range of difficult aqueous matrices. The resulting p-bromophenacyl esters may be separated via either HPLC or GLC techniques depending on desired selectivity and sensitivity. Micromolar concentrations of these acids can be determined to better than ±0.20 μM within 95% confidence intervals. Sewage and marine sediment pore water analyses can be performed on small samples (<25 ml). Similarly, nanomolar determinations are possible in 1-4 L rainwater samples. The analytical method is rapid, economical, and lends itself to routine applications involving parallel determinations of other soluble compounds.
67 citations
TL;DR: By use of a relatively new mixed stationary phase, complete separation of the branched-chain α-keto acids as O -trimethylsilyl-quinoxalinol derivatives is achieved within 10 min by packed column gas chromatography.
65 citations
TL;DR: N-Hydroxymethylpentamethylmelamine displays appreciable chemical stability and 29% was recovered after 60 min incubation in buffer and the known chemical reactivity of carbinolamines means that HMPMM could be involved in the pharmacological or toxic effects of HMM.
52 citations
TL;DR: In this article, the determination of nitrate and bromide directly from aqueous extracts by high-performance liquid chromatography on an amino phase chemically bonded to silica gel is described.
50 citations
TL;DR: In this paper, the configurational assignment of peridinin as 3 S, 5 R, 6 R, 3′ S, 5′ R, 6′ S including ozonolytic degradation of its p -bromobenzoate to derivatives of known chirality obtained from fucoxanthin and violaxanthin is reported.
48 citations
TL;DR: Using ascorbic acid for continuous protection of the labile metabolites a liquid-gel Chromatographic procedure has been developed for the determination of the complete estrogen profile of human urine and all the known labile estrogens were preserved.
47 citations
TL;DR: In this article, the optimal conditions for the reaction of alkyl chloroformates with epinephrine and norepinephrine in aqueous solution have been evaluated.
TL;DR: A sensitive gas chromatographic method for the quantitative analysis of atenolol in human plasma and urine is described and allows determination down to 20 nmol/l (5 ng/ml) in 1 ml of sample with a relative standard deviation below 10%.
TL;DR: A high performance liquid chromatography procedure with an electrochemical detector (ECD) has been developed for the analysis of fatty acids, bile acids and prostaglandins and was applied to the determination of free fatty acids in guinea pig plasma andbile acids in human bile.
Abstract: A high performance liquid chromatography (HPLC) procedure with an electrochemical detector (ECD) has been developed for the analysis of fatty acids, bile acids and prostaglandins. These carboxylic acids were converted to p-hydroxyanilides by reaction with p-aminophenol in the presence of 2-bromo-1-methylpyridinium iodide and triethylamine. The anilides were oxidized in a two-electron process and analyzed by reversed-phase HPLC-ECD. The detection limits were 0.5, 2 and 2ng for stearic acid, chenodeoxycholic acid and prostaglandin F2a, respectively. The method was applied to the determination of free fatty acids in guinea pig plasma and bile acids in human bile.
TL;DR: A high-performance liquid chromatographic (HPLC) procedure for separation of O-acetyl-N-p-nitrobenzoyl derivatives of six neutral glycosphingolipids, used for analysis of human erythrocyte neutral glycolipids.
TL;DR: In this article, the gas chromatographic and mass spectrometric properties of t-butyldimethylsilyl derivatives of organic acids are investigated and reaction conditions are established for complete derivatization of most commonly occurring functional groups in organic acids.
Abstract: The gas chromatographic and mass spectrometric properties of t-butyldimethylsilyl derivatives of organic acids are investigated. Reaction conditions are established for complete derivatization of most commonly occurring functional groups in organic acids with t-butyldimethylchlorosilane in dimethylformamide with imidazole as a catalyst. The chromatographic separation on a capillary column of a mixture of trimethylsilylated aromatic acids is compared with that of the corresponding t-butyldimethylsilyl derivatives. The quality of the electron impact mass spectra of both derivatives of organic acids is compared. The t-butyldimethylsilyl derivatives of organic acids are combining an improved chromatographic and mass spectrometric behaviour with a good thermal and hydrolytic stability as compared with the trimethylsilyl derivatives The method has proved to be very useful in the gas chromatographic mass spectrometric analysis of organic acid profiles.
TL;DR: Optimization of the fluorometric and chromatographic parameters allows analysis of other hydroxylated aromatic compounds, as exemplified by the separation of o-, m- , and p -tyrosine, and dihydroxyphenylalanine.
TL;DR: A gas chromatographic method using either a conventional packed column (3% SP-2250) or a capillary column (SE-30) for the measurement of therapeutic plasma concentrations of tricyclic antidepressant drugs and their demethylated metabolites is described.
TL;DR: A selected ion monitoring method for the determination of 6-oxo-PGF1 alpha, the stable end-product of prostacyclin, in biological fluids has been developed.
Abstract: A selected ion monitoring method for the determination of 6-oxo-PGF1 alpha, the stable end-product of prostacyclin, in biological fluids has been developed. In this method, biosynthetically prepared [2H6]-6-oxo-PGF1 alpha is used as internal standard. The method involves extraction, thin-layer chromatography purification and derivatization into the methyl ester, methoxime, trimethylsilyl ether derivatives by carrying out the methoximation first. Quantitative gas chromatographic mass spectrometric analysis is performed in the electron impact mode by monitoring the [M - (TMSOH + CH3O)]+ fragment ions. The use of this method in the measurement of 6-oxo-PGF1 alpha in serous fluids and in incubation media of serous tissues is described.
TL;DR: In this article, a highly sensitive and selective derivatization of ketosteroids for use in high-performance liquid chromatography with electrochemical detection (HPLC/EC) is described.
Abstract: A highly sensitive and selective derivatization of ketosteroids for use in high-performance liquid chromatography with electrochemical detection (HPLC/EC) is described. When the detector response for three phenylhydrazone derivatives was compared with one another using dehydroepiandrosterone, the p-nitrophenylhydrazone showed the highest sensitivity with a detection limit of 200 pg. Dehydroepiandrosterone and other principal 17-ketosteroids in human blood were quantitatively derivatized into p-nitrophenylhydrazones and efficiently separated by HPLC/EC on a μBondapak C1 8 column using 0.5%. NH4H2PO4/methanol (2:7, v/v).
TL;DR: The absolute configurations of a number of unsaturated hydroperoxy fatty acids obtained by lipoxygenase catalysis were investigated by capillary gas-liquid chromatography after proper derivatization, finding enantiometric compositions which are in good agreement with results obtained by other methods.
TL;DR: In this paper, a method for a fast quantitative determination of the l -isomer in d -penicillamine is described, where l -Leucine is coupled to d, l -penICillamine and the resulting diastereomers separated by reversed phase liquid chromatography.
TL;DR: A derivatization procedure and a high-performance liquid chromatographic (HPLC) method of analysis for pilocarpine are described and its applicability to the analysis of aromatic heterocyclic and alkyl tertiary amines is demonstrated.
TL;DR: In this paper, a sensitive method is described for the analysis of arylhydroxylamines (derived metabolically from arylamines and nitro compounds) in liver homogenates, based on initial extraction of the analyte from the biological matrix with dichloromethane; derivatization in the extraction solvent with p-dimethylaminophenylisocyanate to form a hydroxyurea which is subsequently separated from coextracted materials and reaction by-products by high-performance liquid chromatography (HPLC).
TL;DR: In this article, Dihydrolipoic acid (6,8-dimercapto-n-octanoic acid) was determined after derivatization of the dithiol moiety to a dithiarsolane followed by extractive alkylation of the carboxyl group to the benzyl ester.
TL;DR: A comparison of the amounts of product formed following incubation of labeled and unlabeled delta 1-pyrroline indicated a significant isotope effect in the formation of 2-Pyrrolidinone, suggesting that there are two separate pathways involved in the reaction.
Abstract: delta 1-Pyrroline is a putrescine metabolite that is biotransformed by rabbit liver preparations to 4-aminobutanoic acid and its lactam, 2-pyrrolidinone. Analysis of dilute aqueous solutions of delta 1-pyrroline by proton nuclear magnetic resonance indicated the the predominating species in the liver incubation preparations was delta 1-pyrroline monomer, although other species, such as 4-aminobutyraldehyde an delta 1-pyrroline timer, may exist in equilibrium with the monomer. [2H12]-delta 1-Pyrroline trimer was synthesized from [2H5]pyrrolidine by conversion to the N-chloro derivative followed by dehydrohalogenation. 4-Aminobutanoic acid was measured by a gas chromatographic mass spectrometric assay after derivatization with dimethylformamide dimethyl acetal. The 4-aminobutanoic acid homologue, 5-aminovaleric acid, served as internal standard. 2-Pyrrolidinone was hydrolyzed and measured as 4-aminobutanoic acid. A comparison of the amounts of product formed following incubation of labeled and unlabeled delta 1-pyrroline indicated a significant isotope effect in the formation of 2-pyrrolidinone. The influence of the label was much less on 4-aminobutanoic acid production. The results suggest that there are two separate pathways involved in the reaction.