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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 692-694 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Intestinal permeability ; Urine ; Sugars ; Lactulose ; Mannitol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alteration of intestinal permeability towards compounds like sugars is an indication of abnormalities observed in some diseases. Measurement of the dual sugar absorption of lactulose and mannitol is a non-invasive test of intestinal permeability. The use of this test is however limited by difficulties in the analysis of sugars in urine at low concentrations. In this study we have developed an analytical procedure for quantitative assay of the lactulose-mannitol pair in urine by high resolution gas chromatography. The minimum detectable amounts are 7.5 pg for lactulose and 4.4 pg for mannitol. The calibration curves are linear in the range of 100-6400 mg L-1. Recoveries are within the range 86-102 % for mannitol and 84-105 % for lactulose.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 275-283 
    ISSN: 0935-6304
    Keywords: Purge-and-Trap ; GC-FTIR GC-MS ; Aroma Strawberries ; Fragaria anannassa ; Principal components ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aroma composition of three different Fragaria anannassa cul-tivars Selva, Chandler, and Osso Grande) is studied by purge-and-trap HRGC and the components identified by MRGC-MS and HRGC-FTIR. The chromatographic aroma profiles from four different maturation stages in each variety are compared and the similarities accessed by principal component analysis (PCA). The contents in n-hexanal and hex-2(Z)-enal are characteristic features of the green stage in the three varieties where the content differences in methyl, ethyl, and butyl acetates act as typifying variables among varieties. Ethyl acetate acts as an important differentiation variable for the Selva variety. In the mature stage, the three cultivars may be distinguished from each other through their relative contents of methyl and ethyl 2-methylbutyrate (Selva), methyl 2-methyl-butyrate, methyl butyrate (Chandler), methyl and ethyl butyrates, and methyl caproate (Osso Grande).
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 417-420 
    ISSN: 0935-6304
    Keywords: HPLC-MS ; Particle beam ; HRGC-MS ; Arbutus unedo L. ; Triterpenoids ; Allelopathy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An extract fraction fruits of Arbutus unedo, L., was cleaned-up by column chromatography and shown by NMR to be a mixture of isomers that resists further attempts at separation by conventional chromatographic methods. High resolution gas chromatography-mass spectrometry (HRGC-MS) confirms the presence of triter-penoid isomers but does not allow separation of all the components. This can be improved by trimethylsilylation but the absence of molecular ions and the complex spectra are difficult to interpret. Complete separation can be achieved by high pressure liquid chro-matography (HPLC) coupled to a mass spectrometer by means of a particle beam interface (HPLC-PBMS). Four triterpene com-pounds are identified through analysis of the corresponding mass spectra: α-amyrin, β-amyrin, and Lupeol, have for the first time been identified in Arbutus unedo, L. Fruits. A new natural triterpene tentatively identified as olean-12-en-3β, 23-diol is described for the first time.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 520-523 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Sample preparation ; Solid-phase extraction ; Pattern analysis ; Serum triglyceride fatty acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 494-498 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Pattern analysis ; Amino acids analysis ; Wine characterization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we show that wine free amino acids derivatized as isopropyl N-heptafluorobutyryl esters can be used as a tool for wine characterization. Elementary wines of eight Vitis vinifera varieties were studied during a seven year period. The characteristic wine amino acids for each variety were assessed by means of pattern recognition techniques. A “star symbol plot” was used for graphic representation.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 550-554 
    ISSN: 0935-6304
    Keywords: HRGC-MS ; HRGC-FTIR ; Phenollc acids ; Allelopathy ; Wheat ; Cereal straws ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The allelopathic effects of decomposing wheat straw have been known for some time. In spite of the ecological and economical importance of the subject, only a limited number of compounds have been asociated with the allelopathic activity of wheat straw. In this study the high resolution, speed of analysis, and sensitivity of capillary gas chromatography coupled with mass spectromtry (HRGC-MS) and Fourier transform infrared spectrometry (HRGC-MS-FTIR) have been used in a systematic study of the composition of biologically active wheat straw extracts. Droplet counter-current chromatography (DCCC) was used for fractionation and isolation of components. The extract components were analyzed as methyl derivatives and free hydroxyl groups were located by means of ethylation with diazoethane. Twenty compounds were identified, most of them being phenolic acids. Naphthoic acid, azelaic acid and 1,2,3,5-tetrabromobenzene were also identified.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 735-738 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Silica-bonded cation exchangers ; Amino acids ; TBDMS derivatives ; Clean-up ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 161-164 
    ISSN: 0935-6304
    Keywords: L-2-Hydroxyglutaric acid ; L-2-Hydroxyglutaric aciduria ; Chiral HRGC ; Chiral liquid phases ; Cyclodextrins ; 1(R)-trans-N-N'-1,2-cyclohexenylbisbenzamideoligosiloxane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: L-2-Hydroxyglutaric aciduria is a recently discovered inherited neurometabolic disease for which diagnostic identification of the right enantiomer is required. A method is described where alkyl esters of both L-and D-2-hydroxyglutaric acids are prepared without side lactonization. Esterification is achieved at room temperature by reaction with appropriate alkyl chloroformates. This method avoids lactonization, in contrast to esterification with alcohols in acidic media or with diazomethane. The identity of the derivatives is established by HRGC-FTIR and HRGC-MS. Chiral HRGC separation with capillaries coated with 1(R)-trans-N-N'-1,2-cyclohexylenebisbenzamideoligodimethyL-siloxane and with a cyclodextrin is compared. The method is adequate for quantitative determinations.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 115-118 
    ISSN: 0935-6304
    Keywords: Amino acids ; HPLC Light-scatt ; Light-scattering detection ; ELSD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this communication the authors report the HPLC SEPARATION OF 20 amino acids without derivatization. Separation was achieved by column swithing using a C-8 reversed-phase column and a cationic ion-exchange column. Detection of the underivatized amino acids was accomplished by means of an evaporative laser light-scattering (ELS) detector. The influence of the temperature of the diffusion tube and nebuolzation gas pressure on detector response is reported. The relationship of peak areas vs. mass show a good log-log linearity within a 1:10 range. Detechtion limit is in the order of 200 pmol for most amino acids under the conditions used.
    Additional Material: 6 Ill.
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