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Type: Artigo de periódico
Title: Determination Of Urea In Serum By Using Naturally Immobilized Urease In A Flow Injection Conductimetric System.
Author: de Faria, L C
Pasquini, C
de Oliveira Neto, G
Abstract: A flow injection method was developed, aimed at the determination of urea in human serum. The system makes use of the naturally immobilized urease present in Canavalia ensiformis DC (jack bean). A column is filled with small pieces of this bean, and the sample (50 microliters) containing urea passes through it carried by a 1% NaCl solution. On leaving the column the stream is merged with an alkaline reagent (0.5 mol dm-3 NaOH; 0.5% disodium dihydrogen ethylenediaminetetraacetate). The ammonium ions, arising from the enzymatic reaction that occurs inside the column, are changed into the molecular form, which permeates a polytetrafluoroethylene membrane and is received in a de-ionized water acceptor stream. The ammonia ionizes causing an increase in the conductance, which is proportional to the urea content of the sample. About 40 samples can be processed in 1 h with negligible carry-over and with a relative standard deviation of 1% or less. The results are in agreement with those obtained by a standard spectrophotometric method.
Subject: Conductometry
Enzymes, Immobilized
Hydrogen-ion Concentration
Rights: aberto
Identifier DOI: 
Date Issue: 1991
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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