Bioanalytical flow-injection system for control of hemodialysis adequacy

Potentiometric urea biosensor based on ammonium-ion selective electrode has been used in simple flow-injection bioanalytical system for the determinat ion of removed urea in effluent Liquid during hemodialysis treatment. The i nterferences from other components of the spent dialysate (mainly potassium ions) were eliminated using reference cell detector with non-sensitized am monium-ion electrode. The methods of signal correction were discussed. The presented flow injection analysis (FIA) system allowing monitoring of urea content in the range of concentrations correspond well with the amount of t he analyte in real samples (1-20 mmol/l). Around 25 samples per hour can be analyzed. Due to long operational Life-time of the applied biosensor the F IA system can be useful over 3 weeks. The presented biosensor/FIA system ha s been successfully applied for the biomedical control of real clinical pro cesses. The results of analysis are useful for the evaluation of the clinic al parameters of urea kinetic modeling: parameters KT/V, urea reduction rat io (URR), percentage removal of urea (PRU) and total urea removal (TUR) for intradialytic intervals and urea generation rate (G) and protein catabolic rate (PCRn) for interdialytic intervals. These biomedical parameters are u sed for describing the adequacy of hemodialysis therapy. (C) 2000 Elsevier Science B.V. All rights reserved.