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  • Ammonium  (1)
  • Key words Calcium  (1)
  • Springer  (2)
  • American Physical Society (APS)
  • Blackwell Publishing Ltd
  • 1
    Electronic Resource
    Electronic Resource
    The electrochemical determination of ammonium based on the selective inhibition of the low-spin iron(II)/(III) system of Prussian blue (1997)
    Springer
    Journal of solid state electrochemistry 1 (1997), S. 215-220 
    Details
    ISSN: 1433-0768
    Keywords: Key words Prussian blue ; Ammonium ; Voltammetry ; Flow-through ; Kjeldahl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new method is described for the determination of ammonium in aqueous solutions with electrodes modified by Prussian blue (PB). The specific voltammetric response of PB-modified electrodes to ammonium ions is used for their analytical determination. In the presence of ammonium ions, a concentration-dependent inhibition of the low-spin iron(II/III) system of PB occurs. Only thallium and rubidium ions cause similar inhibition. A useful electrochemical determination method is thus available for detecting ammonium ions in the presence of frequently interfering potassium and sodium ions. Paraffin-impregnated graphite electrodes modified with a mechanically transferred PB layer and bulk-modified PB-composite electrodes are studied. The method is applicable within a concentration range which extends from 4 × 10−5 mol/l to 10−2 mol/l NH4 +. The composite electrode is used in an electrochemical flow-through system in conjunction with the Kjeldahl method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100080050051
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  • 2
    Electronic Resource
    Electronic Resource
    The ionic hemolymph composition of the terrestrial isopod Porcellio scaber Latr. during molt (1997)
    Springer
    Journal of comparative physiology 167 (1997), S. 536-542 
    Details
    ISSN: 1432-136X
    Keywords: Key words Calcium ; Capillary electrophoresis ; Hemolymph ; Isopod ; Molting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We analyzed the ionic composition of the hemolymph of Porcellio scaber in four different stages of the molt cycle using capillary electrophoresis and calcium selective mini- and microelectrodes. The main ions in the hemolymph were K+, Ca2+, Na+, Mg+, and Cl−. The values for total calcium obtained by means of capillary electrophoresis and calcium selective minielectrodes did not differ significantly from each other. In situ measurements of the free Ca2+ concentration ([Ca2+]) by means of calcium-selective microelectrodes indicated that Ca2+ is not bound in the hemolymph. During molt the [Ca2+] is significantly larger than during intermolt. The [Ca2+] increased by 13%, 19% and 18% during premolt, intramolt, and postmolt, respectively. The concentration of the other cations and of Cl− decreased significantly between premolt and intramolt. Thus, the rise of the [Ca2+] in the hemolymph is not due to a general increase in all ions, but rather to the resorption of cuticular calcium. Furthermore, the results suggest that K+, Na+, Mg+, and Cl−are extruded from the hemolymph during and/or after posterior ecdysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050106
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