ScienceAsia 20 (1994): 023-030 |doi: 10.2306/scienceasia1513-1874.1994.20.023

AN ENZYME SENSOR FOR UREA BASED ON CONDUCTIVITY MEASUREMENT

PANOTE THAVARUNGKU^* AND PROESPICHAYA KANATHARANA^**

ABSTRACT: An enzyme-based sensor for the determination of urea is described. The system uses urease immobilized to porous glass and conductivity electrodes to measure the increase in conductivity of the sample solution resulting from hydrolysis of urea into charged products. A linear relationship between the changes in conductivity and urea concentrations was obtained with concentration up to 8 mM (correlation coefficient, r = 0.996 0.002). The response of the enzyme column was stable when used intermittently for up to 48 days, or > 60 h operation time. Good agreement was obtained when the concentrations determined by this system were compared with the diacetylmonoxime colorimetric method (r = 0.994).

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*  Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkla 90112, Thailand.
** Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkla 90112, Thailand.

Received February 24, 1994