公开(公告)号：EP0772693A1

公开(公告)日：1997-05-14

申请号：EP95926583.0

申请日：1995-07-28

申请人： GAMBRO AB

发明人： EDGSON, Raymond ,  OLDE, Bo ,  OLSSON, Lars-Fride ,  GOODMAN JONES, Arfon Cambridge Consultants Ltd.

IPC分类号： G01N33 ,  C12M1 ,  C12Q1 ,  G01N27

CPC分类号： C12Q1/58 ,  G01N27/021 ,  G01N33/493 ,  Y10T436/171538 ,  Y10T436/25

摘要： Method and device for measuring the concentration of urea or a similar substance, in a composite solution, particularly a dialysis solution, by catalytic decomposition of urea by urease. The differential conductivity of the reacted and unreacted solution is measured and is proportional to the urea concentration. The decomposition occurs according to the reaction: (NH2)2 CO + CO2 + 3H2O → 2NH4+ + 2HCO¿3?- (5). By the addition (41, 60) of carbon dioxide gas and by catalyzation with the enzyme urease, the reaction is displaced to the right, which means that said proportionality is valid over a large range of urea concentrations, up to and exceeding 35 mM. The addition of carbon dioxide gas also ensures sufficiently low pH-value in the solution in order to avoid precipitation of calcium carbonate.