A simple and inexpensive multichannel potentiometric blood analyzer for single and nonroutine measurements of electrolyte concentrations

Abstract

A simple and reliable multichannel potentiometric analyzer for fully automatic determination of pH and concentration of sodium, potassium, calcium, and chloride ions in serum, and whole blood samples is described. The analyzer consists of five ion-selective electrodes (ISEs) as electrochemical sensors for selected ions. A flow-through homemade design of ISEs is developed, and the measuring instrument is interfaced to an IBM compatible PC by an analog-to-digital (A/D) converter interface card and peripheral devices control card in order to develop an easy to use, reliable, and virtually maintenance-free potentiometric analyzer. The analytical performance of the described analyzer is compared with the performance of some commercial laboratory analyzers frequently used in clinical laboratories. The comparison study showed good correlation between results obtained by the developed and described instrument and those obtained using commercial analyzers. The range of correlation coefficients found in comparison with different commercial analyzers were pH (r = 0.85–0.97), potassium (r = 0.97–0.98), sodium (r = 0.78–0.94) and chloride (r = 0.87); the poorest correlation was found for calcium concentration determination (r = 0.68–0.77). © 1998 John Wiley & Sons, Inc. Lab Robotics and Automation 10: 205–213, 1998