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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 330 (1988), S. 627-630 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A flow-through electrolysis using a column electrode was applied to the preparation of a reduced ninhydrin reagent suitable for a highly reproducible and sensitive determination of amino acids. Non-reduced ninhydrin solution, which could be stably stored for long duration even in contact with atmospheric oxygen, was fed at a constant flow rate of 0.25 ml min−1 into the flow-through electrolysis cell, whereby ninhydrin was reduced to hydrindantin. The hydrindantin content in the reagent (presumably 1.61 mol%) was sufficiently constant for the subsequent quantitative reaction of the amino acids being eluted from the HPLC system. The electrolytically prepared reagent was practically identical with those prepared by chemical reduction.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1439-863X
    Keywords: Key words Dissolved organic carbon ; Ado River ; Lake Biwa ; Characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine the chemical and physicochemical characteristics of dissolved organic carbon in the Ado River and the Yasu River, the main rivers flowing into Lake Biwa, the adsorption behavior onto hydrous iron oxide (HIO) and the reactivity to KMnO4 oxidant were investigated in parallel with measurement of the distribution profiles of dissolved organic carbon (DOC) along the rivers. In one year of observation at the mouths of the two rivers, DOC concentrations were found to vary in the Ado over the range 0.28–1.21 mg C l−1 and in the Yasu over the range 1.01–2.68 mg C l−1. Act-DOC, one of the fractions separated from the total DOC by its adsorption-active character onto HIO at pH 4, was thought primarily to control the variation of total DOC, as in Lake Biwa. The int-DOC, another fraction separated by its adsorption-inert or -inactive character onto HIO, remained at almost a steady value around 0.18 ± 0.07 mg C l−1 in the Ado, which was lower than that (0.35 ± 0.05 mg C l−1) in Lake Biwa. The act-DOC in river waters was reactive to KMnO4 oxidant, showing a linear relation with the amount of permanganate consumed for the reaction (chemical oxygen demand: COD). In river waters, the relation can be approximated by a straight line expressed as COD (mg O2 l−1) = 0.64 × act-DOC (mg C l−1) − 0.02. In contrast, in the lake water the relation was COD (mg O2 l−1) = 0.97 × act-DOC (mg C l−1) − 0.50.
    Type of Medium: Electronic Resource
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