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Flow Injection Analysis for the Determination of Urea in Cow’s Milk
Bestämning av urea i komjölk med FIA (flödesinjektionsanalys)
Acta Veterinaria Scandinavica volume 26, pages 396–404 (1985)
Abstract
An inexpensive and easily automated flow injection method for determination of urea in cow’s milk was evaluated. Urea is hydrolysed by urease and in a gas diffusion cell the ammonia formed passes a membrane into an indicator solution. The resulting colour change of the indicator is measured at 590 nm.
The repeatability of the analysis, expressed as the coefficient of variation (C.V.), was between 0.5 and 1.2%. Measured (y) and expected (x) milk urea concentrations after addition of known amounts of urea were related according to the equation y = 1.00× – 0.12 with a C.V. for the regression of 1.8%. Recommended amounts (0.02 %) of the preservative bronopol (2-bromo-2-nitropropane-1,3-diol) added to the milk did not affect the results (P > 0.05).
Sammanfattning
Den utvärderade metoden bygger på att ammoniakgas som bildats efter hydrolys av mjölkurean diffunderar genom ett membran in i en indikatorlösning, varefter färgomslaget hos indikatorn mäts i en fotometer vid 590 nm. Reproducerbarheten, uttryckt som variationskoefficient, låg mellan 0,5 och 1,2 %. Tillsats av kända mängder ureastandard till mjölk före analys visade på en mycket god överensstämmelse mellan förväntade och erhållna värden. Normal tillsats av konserveringsmedlet bronopol (0,02 %) påverkade inte resultaten (P > 0,05).
FIA-metodiken bedöms vara väl lämpad för rutinmässig analys av urea i komjölk då den är snabb, säker och billig.
References
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Oltner, R., Bengtsson, S. & Larsson, K. Flow Injection Analysis for the Determination of Urea in Cow’s Milk. Acta Vet Scand 26, 396–404 (1985). https://doi.org/10.1186/BF03546539
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DOI: https://doi.org/10.1186/BF03546539