Spectrophotometric flow injection determination of total phosphorus in beer using on-line UV/thermal induced digestion.
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.
Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Porto, Portugal.
S M
SM
Fernandes
J L
JL
Lima
A O
AO
Rangel
D001515:Beer / Q000032:analysis*; D017022:Flow Injection Analysis; D006358:Hot Temperature; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000032:analysis*; D011786:Quality Control; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000379:methods*; D017971:Tin Compounds; D014466:Ultraviolet Rays
D017971:Tin Compounds; C023599:stannous chloride; D010758:Phosphorus