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DETERMINATION OF TOTAL SULPHUR DIOXIDE IN BEER BY FLOW INJECTION SPECTROPHOTOMETRY USING GAS‐DIFFUSION AND THE MERGING ZONES TECHNIQUE
Author(s) -
Firnandes Sílvia M. V.,
Rangel Antonio O. S. S.,
Lima José L. F. C.
Publication year - 1998
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1998.tb00992.x
Subject(s) - chemistry , analytical chemistry (journal) , diffusion , volumetric flow rate , chromatography , relative standard deviation , sulfur dioxide , formaldehyde , sulfur , matrix (chemical analysis) , spectrophotometry , detection limit , thermodynamics , inorganic chemistry , physics , organic chemistry
A flow injection system for the determination of total sulphur dioxide in beer is described. The methodology involves the same colorimetric reaction of the reference method between SO 2 , prosaniline and formaldehyde. The sample is introduced into the manifold without previous pretreatment, the hydrolysis process, isolation of the SO 2 from the matrix and the colorimetric reaction, being carried out inside the flow tubes. To isolate the SO 2 , a gas‐diffusion unit was included in the system and to minimise p‐rosaniline consumption, a merging zones technique was used. The results obtained were in good agreement with a reference method (relative deviations lower than 5%), the precision being better than 2.5% (relative standard deviation). A sampling‐rate of 30 samples per hour was obtained and the consumption of p‐rosaniline was reduced 10 fold when compared to the reference method.