Further electrode evaluation of the Nova 2 ionised calcium instrument

Introduction In the original evaluation of the Nova 2 analyser [1] inter-electrode differences were shown which would have necessitated the re-establishment of the ionised calcium reference range each time that the calcium ion-selective electrode was changed. The manufacturers (Nova Biomedical, Newtown, Mass, USA) have now replaced the electrodes which showed slow and variable response times to serum, and it has been possible to compare these two replacement electrodes with the original electrode (still in service after 14 months). Another electrode, replaced under warranty, and two supplied with a second instrument on loan from the British Agents (American Hospital Supplies,.Didcot, Oxon, UK) were also compared with the original electrode. In all a total of six electrodes were evaluated.