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Sequential flow-injection spectrofluorimetric determination of coumarins using a double-injection single-line system

✍ Scribed by P. Solich; M. Polášek; R. Karlíček

Publisher
Elsevier Science
Year
1995
Tongue
English
Weight
510 KB
Volume
308
Category
Article
ISSN
0003-2670

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✦ Synopsis

A simple and rapid flow-injection (FI) technique with spectrofluorimetric detection is presented for the sequential determination of two model compounds: 6-methoxy-7-hydroxycoumarin (scopoletine) and 7-hydroxycoumarin (umbelliferone) without prior separation. A double-injection valve with a single-line flow-injection system is used for the simultaneous injection of a sample and a phosphate buffer solution in aqueous 50% (v/v) ethanol in order to measure the fluorescence signal of the analytes successively at pH * 6.0 and 11.0. The optimum excitation and emission wavelengths are 350 nm and 2 418 nm, respectively. Using a calculation method based on differential fluorimetry it is possible to determine 2 1 pm01 1-l of scopoletine in the presence of I 9-fold molar excess of umbelliferone or 1 pmol lP ' of umbelliferone in the presence of I 23-fold molar excess of scopoletine. This technique can be used for sequential determination of various other fluorescent compounds (exhibiting pH-dependent excitation spectra) in two-component mixtures; it allows for a quick interchange of reagents within a single-line FIA system and the reagent consumption is decreased substantially.

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