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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 33 (1985), S. 336-339 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European food research and technology 179 (1984), S. 305-307 
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary The potential of someLactobacillus, Staphylococcus andStreptococcus strains for producing putrescine and cadavering during growth in vacuum packed beef was studied. Throughout the six weeks storage at 4 °C the samples were sensorily assessed at regular intervals, and their pH values and diamine contents were determined. The amines were quantified by means of capillary gas chromatography. The putrescine and cadaverine contents remained within the range of the initial values until overt spoilage at the end of the sixth week (at about 0.08 mg amine/100 g).
    Notes: Zusammenfassung VerschiedeneLactobacillus-, Staphylococcus-undStreptococcus-Stämme wurden auf ihre Fähigkeit geprüft, in vakuumverpacktem Fleisch Putrescin und Cadaverin zu bilden. Während einer sechswöchigen Lagerung bei 4 °C wurden die Proben in regelmäßigen Abständen sensorisch bewertet und ihr pH-Wert bestimmt. Den Amingehalt ermittelten wir mit Hilfe der Capillar-Gaschromatographie. Die Aminkonzentrationen blieben bis zum deutlichen Verderb am Ende der sechsten Woche im Bereich der Anfangswerte von etwa 0,08 mg/ 100 g.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 209-214 
    ISSN: 0935-6304
    Keywords: Dual capillary gas chromatography ; non-methane hydrocarbons (NMHCs) ; refocusing ; PLOT column ; carbon dioxide interference ; ambient air analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical method based on a dual capillary gas chromatographic technique combining the advantages of GasPro PLOT and a non polar narrow bore WCOT column was developed for the analysis of air samples containing C2-C9 NMHCs. A refocusing step was not required due to the fast heating rate of the sample preconcentration trap and the resolving power of the PLOT column for C2 and C3 NMHCs. Water had to be removed from the air samples to avoid plugging of the columns if the initial GC oven temperature was below ambient temperature. To dry air samples, a scrubber and a cryogenic technique were employed. The interferences caused by carbon dioxide were reduced by purging the loaded sample preconcentration trap with helium. The dual column system was compared to a method employing a refocusing device and a single narrow bore WCOT column. Both systems provided a high degree of precision. However, the dual column approach was superior to the single column system due to better resolution of low molecular weight components.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 340 (1991), S. 672-677 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An improved analytical procedure has been developed for the detection of formaldehyde, acetaldehyde, acetone and other volatile carbonyls in clean air. For sampling, 2,4-dinitrophenyl-hydrazine (DNPH) coated silica gel cartridges were used. DNPH reacts with carbonyls and forms carbonyl hydrazones which are extracted with acetonitrile and subsequently separated by reversed phase HPLC. Sampling flow rates up to 3.5 l/min were tested. The quantification limit of the complete sampling and analytical procedure is 60 ng carbonyl which corresponds to a mixing ratio of 1 ppbv HCHO in a 45 l air sample taken during a sampling time of 13 min. Carbonyl mixing ratios down to 0.1 ppbv can be determined. The collection efficiency and the elution recovery range between 96 and 100%; the precision is ±5% for HCHO and ±4% for CH3CHO at mixing ratios of 1 ppbv. This technique can also be applied for the determination of aldehydes and ketones in the aqueous phase, e.g. cloud and fog water. In this case, carbonyls were converted to hydrazones simply by mixing the aqueous sample with an acidified DNPH solution. After 40 min reaction time, the hydrazones were analysed by HPLC. The detection limit was 0.2 μmol HCHO/l. Possible interference caused by ozone and NO2 was eliminated by using KI filters connected in series with the DNPH-coated cartridges. The analytical procedure was tested at a mountain measuring station and proved to be a suitable method for monitoring carbonyl compounds in clean air.
    Type of Medium: Electronic Resource
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