Branched deoxyaldaric acids from alkaline degradation of carbohydrates: Structure determination by mass spectrometry of trimethylsilyl derivatives

The deoxyaldaric acids corresponding in structure to the 3-deoxy-2-C-(hydroxymethyl)aldonic (isosaccharinic) acids have been identified as products of treatment of various carbohydrates with alkali and oxygen-alkali. The structures of the acids were determined from the mass spectra of their Me3Si derivatives on the basis of previously known, specific fragmentation reactions. The g.l.c.-m.s. technique was used, and g.l.c. retention data are given. The identified species are 2-deoxy-3-C-(hydroxymethyl)tetraric, 3-deoxy-2-C-hydroxymethyl-erythro-pentaric, 3-deoxy-2-C-hydroxymethyl-threo-pentaric, 2-methyltartronic, 2-(2-hydroxyethyl)tartronic, and 2-(2,3-dihydroxypropyl)tartronic acids. Their formation from 4-O-substituted uronic and ulosonic acids is briefly discussed

Gas chromatography - mass spectrometry of sugars and related hydroxy acids as trimethylsilyl derivatives

The application of gas chromatography and mass spectrometry has contributed to the rapid progress of carbohydrate chemistry during the past ten years. The methods are indispensable tools in current research on carbohydrate reactions during pulping processes.<p> Acyclic ether, ester, and oxime trimethylsilyl derivatives are useful for gas chromatographic analysis of alditols, aldoses, ketoses, aldonic acids, aldaric acids and uronic acids. These derivatives have been studied in detail by mass spectrometry and shown to be advantageous for structural analysis. The mass spectrometric fragmentation of glycosidic trimethylsilyl derivatives has also been investigated. An important application is the identification of products from methylation analysis

Mass spectrometry of alditols as trimethylsilyl derivatives

Trimethylsilyl ethers of alditols with 3, 4, 5 and 6 C atoms were investigated. The mass spectra are unusually clearly correlated with the structures. The predominant fragmentations are cleavages in the carbon chain and rearrangement loss of trimethylsilanol. The spectra are closely related to those of the methyl ethers. A spectrum unambiguously identifies a compound as an alditol and permits the determination of its molecular weight

Mass spectrometry of aldonic and deoxyaldonic acids as trimethylsilyl derivatives

Open-chain trimethylsilyl derivatives of aldonic and deoxyaldonic acids, which can be prepared from salts of the acids, are well suited for structure determination by mass spectrometry. The study is focussed on aldonic and unbranched monodeoxyaldonic acids, but several dideoxyaldonic and branched deoxyaldonic acids are included. Spectra of the derivatives of glycolic, lactic and hydracrylic acids are discussed.<p> The structural isomers exhibit interpretable differences, whereas the spectra of the diastereomers are similar. The molecular weight and the number of OH groups can be deduced from the spectra, as well as the position of the “deoxy group” in unbranched deoxyaldonic acids. The most prominent fragmentations are α-cleavages of the carbon chain, frequently followed by rearrangement loss of trimethylsilanol. A structurally significant McLafferty-type rearrangement of a trimethylsilyl group is described. Several types of ions decompose by expulsion of small molecules such as CO, CH2O and CO2

High ambient concentrations of monoterpenes in a Scandinavian pine forest

Total monoterpene levels of the order of 100 μg/m3 were assessed in the summer night air of a typical young planted forest of Scots pine (Pinus silvestris) in Sweden. These concentrations are much higher than those reported in previous studies of ambient monoterpenes. Predominant species were α-pinene and 3-carene. Camphene, β-pinene, myrcene, β-phellandrene and limonene were other prominent components determined. The monoterpenes were shown to originate almost exclusively from Scots pine and the proportions between them to be characteristic of this conifer species

Conversion of dehydroascorbic acid to a branched hexaric acid in neutral and alkaline aqueous solution

Dehydroascorbic acid is shown to be converted to 2-(threo-1,2,3-trihydroxypropyl)tartronic acid in aqueous alkaline solutions. The structure of the acid was determined by mass spectrometry of its acyclic Me3Si derivative. Mass spectrometric and chromatographic data are compared with those of related compounds. The acid is formed by a benzilic acid rearrangement of the intermediate 2,3-hexodiulosonic acid. The rate of formation at 38°C was studied quantitatively by glc. It increases at increased alkalinity but is significant even at physiological pH. The presence of oxygen does not substantially influence the reaction

Gas-chromatographic analysis of sugars and related hydroxy acids as acyclic oxime and ester trimethylsilyl derivatives

A g.l.c. method which makes possible the simultaneous analysis of the common types of acidic and neutral sugars is described. Particular advantages are achieved with hydroxy acids, ketoses, and uronic acids. Acids and lactones are first converted into their sodium salts. Free or potential aldehydo and keto groups are transformed into oximes or O-methyloximes. Fully substituted acyclic ester and oxime trimethylsilyl derivatives are prepared with bis(trimethylsilyl)trifluoroacetamide and chlorotrimethylsilane. Syn and anti isomers of the oximes are formed, but a stationary phase can often be chosen on which the two peaks coincide. The silicone stationary phases OV-1, OV-17, QF-1, and XE-60 were used. Retention data are given for aldonic and deoxyaldonic acids, aldoses, ketoses, and uronic acids. Relationships between structure and retention are discussed. The derivatives are suited to structural analysis by gas chromatography—mass spectrometry

Fruktsocker mot Blodsocker

Vanligt socker, sackaros, spjälkas till lika delar fruktos och glukos och dominerar svenskars upptag av fruktos. Fruktos fångas upp i levern och omsätts där efter behov till glukos och glykogen eller till fettsyror.<p> Människan är väl anpassad till hälsoriktiga frukter och bär med fruktos. Högt blodsocker bakom övervikt och diabetes orsakas inte av fruktos utan av glukos från främst sackaros och stärkelse

Hotell och Konferens

Hotell och konferenser har egna starka skäl att erbjuda en hälsoriktigare attraktiv frukost och bidrar då också till bättre folkhälsa. Gäster får impulser som kan sprida bättre vanor.<p> Bra frukostar vid sex olika hotell har jämförts för tio delområden. Stora skillnader finns för vissa av dessa områden vilket visar på stor potential för förbättringar. Särskilt för flingor, fil, bröd, frukt och drycker behöver utbudet förbättras. Information på buffébordens skyltar och via hemsidor kan utvecklas till bra stöd för gäster

Biokemi bakom aktuell diagnos

Intresset för odiagnosticerad underfunktion av sköldkörtelhormoner, hypotyreos, ökar nu snabbt. Problemet kopplar till ospecifika diagnoser som utmattningssyndrom, kronisk trötthet och fibromyalgi. <p> Rapporten syftar till att belysa hormonernas biokemi som en grund för förståelse av orsaker bakom problemen. Bland dessa belyses brist på jod och selen, exponering för kvicksilver och andra miljögifter samt långvarig fysisk och psykisk stress.<p> Hypotyreos kan oftast behandlas framgångsrikt med tillskott av hormonerna tyroxin, T4, och liotyronin, T3