Potentiometric determination of dialysate urea nitrogen

An enzymatically modified ammonium ion-selective electrode has been applied for the determination of urea in spent dialysate. The biosensor has been u sed in a simple flow-injection analysis (FIA) system. The system enables on e to perform over 25 dialysate urea nitrogen (DUN) determinations per hour. The interferences from other components of posthemodialysis fluid were eli minated by simultaneous measurements with non-modified enzymatically ion-se lective electrode. It is possible to use both the sensors in a simplified d ifferential potentiometric system. The results of DUN determination using t he biosensor/FIA system and a conventional method of urea determination wer e comparable. The presented analytical system can potentially find wider bi omedical application in the monitoring of hemodialysis progress. (C) 2000 E lsevier Science B.V. All rights reserved.