| Progress in pulsed-current Karl Fischer coulometry using diaphragm-free cells. | |
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MedLine Citation:
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PMID: 11225824 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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Factors influencing the accuracy of water determinations using diaphragm-free, pulsed current Karl Fischer (KF) coulometry were investigated with the new Metrohm 756 instrument. Results obtained with commercially available reagents from Riedel-deHaen and Merck were compared with home-made ones that were especially designed to minimize the formation of iodine-consuming reduction products generated in the cathode reaction. Positive errors in the range 2-5% were found for the commercial reagents as compared to 0.2-1% for the home-made ones which were buffered at about pH 10 containing modifiers like chloroform, hexanol or ethylene glycol. Except for the composition of the KF-reagent, the cathode current density and the titration rate were found to be critical parameters for the accuracy of the determinations. For all reagents investigated, the best results were obtained for the maximum generator current 400 mA (corresponding to a current density of 1,400 mA cm(-2)) in combination with a maximum titration rate of 2,000 microg min(-1). Surprisingly, the errors found under optimum conditions for the pulse technique were always somewhat larger than the corresponding values obtained with continuous coulometry. |
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Authors:
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U Nordmark; A Cedergren |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Fresenius' journal of analytical chemistry Volume: 367 ISSN: 0937-0633 ISO Abbreviation: Fresenius J Anal Chem Publication Date: 2000 Jul |
Date Detail:
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Created Date: 2001-02-27 Completed Date: 2001-04-05 Revised Date: 2003-10-31 |
Medline Journal Info:
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Nlm Unique ID: 9114077 Medline TA: Fresenius J Anal Chem Country: Germany |
Other Details:
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Languages: eng Pagination: 519-24 Citation Subset: - |
Affiliation:
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Department of Chemistry, Umeå University, Sweden. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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