Showing papers on "Derivatization published in 1974"
TL;DR: In this paper, mass spectra of permethylated methyl glycosides show ions derived from a number of specific degradation pathways, and these fragmentations have been carefully studied by using deuterium-labelling techniques.
Abstract: Publisher Summary This chapter describes that mass spectrometry (m.s.) has become an important and versatile technique in carbohydrate chemistry. The chapter deals with m.s. as a tool in the structural analysis of naturally occurring carbohydrates. The mass spectra of permethylated methyl glycosides show ions derived from a number of specific degradation pathways. These fragmentations have been carefully studied in the chapter, by using deuterium-labelling techniques. Direct derivatization of reducing sugars by permethylation, peracetylation, or per( trimethylsilyl )ation gives a mixture of glycosides. These derivatives are suitable for g.1.c. analysis, although, for complex mixtures of sugars, the multiplicity of peaks caused by the derivatization may complicate elucidation of the results. The partially methylated sugars are separated and converted into the methyl glycosides, and these are methylated with trideuteriomethyl iodide. The substitution pattern of the trideuteriomethyl groups can be determined by m.s., and the nature of the sugar ascertained by g.1.c. (by comparison with the permethylated compound used as the reference sample).
329 citations
TL;DR: Based on solvent-free gas chromatography of the n -propyl, procedures are described for the routine determination of amino acid profiles in biological samples including protein hydrolysates, plant tissue extracts, urines and sera, indicating that a coefficient of variation of 2–5% is attainable.
254 citations
TL;DR: Halogenated derivatives of phenolic acids have been prepared by a convenient procedure and procedures have been developed using these derivatives for the determination of spinal fluid levels of vanillylmandelic acid, homovanillic acids, probenecid, and 2-pyrrolidone-5-carboxylic acid.
73 citations
TL;DR: The butyl derivatives of several barbiturates that are unresolved in the form of underived compounds or methyl esters can be resolved, thus overcoming many previous analytical limitations.
Abstract: A recently developed procedure for alkylation of organic acids has proven extremely successful for preparation of volatile alkyl derivatives of the barbiturates for gas-chromatographic analysis. Soluble salts are formed in a mixture of N,N-dimethylacetamide and methanol. These in turn react rapidly with alkyl iodides to form the corresponding alkyl derivatives. The butyl derivatives of barbiturates, prepared in this manner, are separable by high-resolution gas-chromatography. Any of 14 barbiturates can be determined simultaneously or separately (although there is some overlap with certain uncommon barbiturates). The butyl derivatives of several barbiturates that are unresolved in the form of underived compounds or methyl esters can be resolved, thus overcoming many previous analytical limitations.
67 citations
TL;DR: A new method of mass chromatography for qualitative and quantitative determinations involving the multi-deuterium-labeled conjugated bile acids as internal standards and the reciprocal of the relative intensity of the peaks on the mass chromatogram was developed.
44 citations
42 citations
36 citations
TL;DR: A new reagent which improves methods applying 5-dimethylaminonaphthalene-1-sulphonyl chloride, and a version of the integrated ion current technique allows the determination of piperidine in tissues in picomole quantities.
Abstract: Piperidine is a putative neurotransmitter. Its sensitive determination is one of the prerequisites for the evaluation of its assumed physiological role. For its derivatization 5-di-n-butylaminonaphthalene-1-sulphonyl chloride, a new reagent which improves methods applying 5-dimethylaminonaphthalene-1-sulphonyl chloride, is used. Reaction of the perchloric acid tissue extract with this reagent, thin-layer chromatographic separation of the fluorescent derivatives and mass spectrometric evaluation of the di-n-butylaminonaphthalenesulphonyl piperidine spot by a version of the integrated ion current technique allows the determination of piperidine in tissues in picomole quantities. Standard deviation of the determinations of 2 to 16 pmol of piperidine added to 50 mg of brain tissue was ±8%. The method was applied to the analysis of different tissues. Brain concentrations of piperidine in different species were found to be lower by a factor up to 100 in comparison with published data.
32 citations
29 citations
TL;DR: The resulting cyclic derivative, 2,2-bis(chlorodifluoromethyl)-4-subst.-1,3-oxazolidin-5-one was of essentially lower polarity and could be used for gas chromatography and possible application in the analysis of both protein and thyroid amino acids.
21 citations
TL;DR: The oxazolidinones of tyrosine and mono- and diiodotyrosines were prepared and, after treatment with acetic, trifluoroacetic, heptafluorobutyric or pivalic anhydride or with hexamethyldisilazane, they were chromatographed on silicone phases and the relative molar responses to hexadecane and lindane were determined.
TL;DR: A method for qualitative and quantitative analysis of phenols by gas-liquid-solid chromatography has been developed and compared with analyses made by capillary-column gas liquid chromatography.
TL;DR: A method is described for the chemical analysis of lasalocid, formerly known as antibiotic X-537A, based on quantitative thermolysis of the antibiotic to a retroaldol ketone which is assayed by gas chromatography.
TL;DR: The GC-MS characteristics of the partial O-ethyl ethers of normetanephrine isothiocyanate, metanephine and VMA ethyl ester are described and the isomeric 3-methoxy-4-hydroxy and 4-mETHoxy-3-Hydroxy derivatives can be identified and quantitated in biological samples by this method.
TL;DR: The authors separated methyl derivatives of methyl(methyl-α-d -glucopyranosid)uronate without derivatization as well as corresponding per-O-trimethylsilyl, trifluoroacetyl and perO-acetyl derivatives on columns of different polarity.
TL;DR: In this article, the most suitable derivatives for GLC separation appeared to be the thioalkylbenzoates, which enabled all of the normal and branched mercaptans studied to be resolved on an SE-30 column.
TL;DR: The potential utility of new chiral reagents to form the diastereomers of amino acids for GC resolution on conventional columns is reported.
TL;DR: In this article, N-NO-4-Otrimethylsilyl-l-trifluoroacetamide was used to derive N-nitrosoamino acid methyl esters.
TL;DR: The L- and D-amino acids could be resolved by coupling N-trifluoroacetyl-prolyl chloride (L-TPC) as the resolving agent by gas chromatography by analyzing the reaction conditions and relation between separation factors and structure of amino acids.
Abstract: The L- and D-amino acids could be resolved by coupling N-trifluoroacetyl-prolyl chloride (L-TPC) as the resolving agent by gas chromatography. The reaction conditions were studied in detail, the solvents, the amount of resolving agent and reaction time for quantitative derivatization. The 22 stationary phases were studied for chromatographic separation. Relative retention times and separation factors were determined for each enantiomeric pair of 15 amino acids and glycine. Relation between separation factors and structure of amino acids were also discussed.
TL;DR: The usual methods of derivatization of alcohols that are unstable in the mass spectrometer fail with those alcohols which are acid-and/or base-sensitive.
Abstract: The usual methods of derivatization of alcohols which are unstable in the mass spectrometer fail with those alcohols which are acid- and/or base-sensitive. Examples include the acid-sensitive acetal group and the acid- and base-sensitive oxirane ring, as in structures I and II, respectively.
TL;DR: The use of ultrasonication to remove dissolved air while pulling a vaccumm on the sample solution prior to hydrolysis assured a good recovery for methionine and cystine as discussed by the authors.