ABSTRACT
A number of commercial systems are suitable for recording the p.d.’s generated by ionselective/reference electrode pairs. At their most basic they are based on the high input impedance voltmeters used in conjunction with commercial glass pH electrodes. Alternatively it is possible to manufacture measuring systems from individual electronic components. Financial considerations have a bearing on which course to take. However, if you feel confident enough to manufacture your own recording system, it gives you flexibility in tailoring the apparatus to your own experiment. Whichever course is taken it is important to understand the characteristics required of such measuring systems and this will be considered below. Most commercial systems are accompanied by detailed technical specifications and these should be checked that they comply with the requiremnts given here.
