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A flow injection system for the automatic determination
of total phosphorus in beer is described. The
developed manifold uses a two-stage photooxidation/thermal
digestion procedure together with oxidizing and hydrolyzing
reagents to convert all forms of phosphorus
compounds to orthophosphate. Polyphosphates are hydrolyzed
by acid and heat, and organo-phosphates are digested
by UV-catalyzed peroxodisulfate oxidation. The
orthophosphate formed is then spectrophotometrically determined
by the phosphomolybdenum blue reaction, using
stannous chloride as reducing agent. The results obtained
for a set of 19 beer samples (with concentrations from 120
to 735 mg P/L) were in good agreement with the reference
method, the maximum relative deviation found being
4.7%. Relative standard deviations for ten consecutive determinations
were lower than 1.5%, and a detection limit
of 1 mg P/L was achieved.
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Citação
FERNANDES, Sílvia M. V. ; LIMA, L. F. C. ; RANGEL, António O. S: S. - Spectrophotometric flow injection determination of total phosphorus in beer using on-line UV/thermal induced digestion. Fresenius Journal of Analytical Chemistry. ISSN: 0937-0633. Vol. 366 (2000), p.112–115
Editora
Springer-Verlag