Spectrophotometric flow injection determination of total phosphorus in beer usi...

• Author(s): Fernandes, Sílvia M. V. ; Lima, José L. F. C. ; Rangel, António O. S. S.
• Date: 2000
• Persistent ID: http://hdl.handle.net/10400.14/6549
• Origin: Veritati - Repositório Institucional da Universidade Católica Portuguesa
• Document Type: Article
• Language: English

Description

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.