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  • 1
    ISSN: 0935-6304
    Keywords: Capillary GC ; Mass selective detection ; Chronic renal failure ; Hemodialysis ; Hemofiltration ; Peritoneal dialysis ; Furanpropionic acid ; Hippuric acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solid-phase extraction, capillary GC, and mass selective detection have been used to determine 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (furanpropionic acid) and hippuric acid in the plasma of patients with chronic renal failure. The concentrations of furanpropionic acid and hippuric acid were found to be highly elevated and reached levels of 4.56 ± 2.37 mg/dl (10 to 20-fold higher than normal) and 12.90 ± 14.06 mg/dl (40 to 60-fold), respectively. Treatment by hemodialysis and hemofiltration effectively eliminated hippuric acid (on average by 66 and 56%, respectively) but had little effect on furanpropionic acid. Intermittent peritoneal dialysis gave the best long-term results. Both components were maintained at a lower level than by hemodialysis and hemofiltration.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 308-311 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Mass selective detection ; Multidimensional GC-MSD ; Fish oil ; Furan fatty acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation and analysis of furan fatty acids and other minor component fatty acids present at very low concentrations in complex sample matrices, such as fish oil or lipids derived from liver and testes, require several pre-analytical separation steps if single column gas chromatography is to furnish sufficient resolution: after extraction and transesterification hydrogenation, urea complex precipitation and argentation TLC have been applied prior to GC analysis of furan fatty acids.By using multidimensional GC-MSD with cooled injection and flow-controlled column switching with intermediate cold trapping, it has been possible to identify directly the methyl esters of furan fatty acids without further pre-analytical separation.The most common of the furan fatty acids can be subdivided into two groups depending on whether they bear a propyl or pentyl side group in the 5-position of the furan ring. In addition to the eight furan fatty acids known to be present in fish oil, six new ones were identified, four with propyl substitution and two with pentyl substitution. Four have earlier been reported to be present in the hepatopancreas of crayfish and in fish tissue, whereas the propyl-substituted 16,19-epoxy-17,18-dimethyldocosa-16,18-dienoic acid and the pentyl-substituted furan fatty acid 6,9-epoxy-7-methyltetradeca-6,8-dienoic acid were hitherto unknown.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Mass spectrometry ; Fatty acids ; 2-Substituted 4,4-dimethyloxazoline derivatives ; Lipids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fatty acids from blood serum lipids and fish oil preparations are derivatized with 2-amino-2-methyl-1-propanol to form 2-substituted 4,4-dimethyloxazolines. The derivatives are separated on a 25 m × 0.25 mm FFAP column and identified by mass spectrometry using electron impact ionization. The positions of the double bonds of mono- and polyunsaturated fatty acids can be easily and reliably recognized from a characteristic fragmentation feature of the oxazolines. Several unsaturated C16 to C22 fatty acid isomers are identified whose exact structure has not been derived from the commonly used methyl esters.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 815-818 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Mass spectrometry ; Fish oil supplementation ; Furanpropionic acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (furanpropionic acid), a metabolite commonly found in human blood and urine, is one of the major acidic components which accumulates in the blood of patients with renal failure. Polyunsaturated fatty acids such as eicosapentaenoic acid (C20:5 ω-3) and long chain furan fatty acids, both present in commonly available fish oil capsules, are regarded as possible precursors of furanpropionic acid. Because of its strong binding to albumin and its various interactions with other endogenous and exogenous components, it is of great importance to determine the concentration of furanpropionic acid in blood and urine regularly.Solid phase extraction has been used to concentrate furanpropionic acid from both blood and urine samples. After esterification with ethereal diazomethane, gas chromatographic separation was performed on a HP-1 column (dimethylpolysiloxane). Quantitation with an internal standard was performed by mass selective detection in SIM-mode, qualifier ions being used for identification and accuracy.Fish oil supplementation of the diet of 24 patients for four weeks led to 3-fold and 5 to 6-fold increases in the levels of furanpropionic acid in serum and urine, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 543-548 
    ISSN: 0935-6304
    Keywords: GC-FTIR-MS ; Polyunsaturated fatty acids ; Methyl esters ; Oxazolines ; cis/trans isomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Identification of cis/trans isomers of unsaturated fatty acids cannot usually be achieved by GC-MS (gas chromatography-mass spectrometry) without reference substances. In this study a GC-FTIR-MS system (gas chromatography-Fourier transform-mass spectrometry) was used to identify fatty acid methyl esters (FAMEs) and differentiate between the cis/trans isomers. Besides methyl esters, 2-alkenyl-4,4-dimethyloxazoline derivatives (DMOX), which have been used to locate double bond positions of unsaturated fatty acids, were examined with respect to their suitability for cis/trans differentiation.A combined GC-FTIR-MS system with a wide band (4000-550 cm-1) mercury cadmium telluride (MCT) detector was used in series and parallel to identify 31 reference unsaturated fatty acids, including 7 pairs of cis/trans isomers. Serum samples of healthy persons and commercially available fish oil were analyzed as examples of complex mixtures. Using splitless injection the detection limit for the less sensitive IR detector was 25 ng/μl in case of the weak cis and trans bands.In the FTIR spectra cis/trans isomers were identified by analysis of bands arising from C—H out-of-plane (oop) bending: for both the FAME and DMOX derivatives cis-1,2-disubstituted double bonds give a strong band near 720 cm-1 and the corresponding trans isomers near 967 cm-1. cis Isomers could be identified further by a band at 3012 cm-1. With the combined data of the GC-FTIR-MS system it is now possible to identify polyunsaturated fatty acids with regard to the discrimination of cis/trans isomers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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