GLASS PH ELECTRODES WITH IMPROVED TEMPERATURE CHARACTERISTICS .2. SYSTEMS WITH CONVENTIONAL INNER REFERENCE ELECTRODES

Glass electrodes with internal filling solutions containing zwitterionic buffers are shown to have standard potentials that vary linearly with temperature over a wide range (at least 5-50-degrees-C). This reduces the errors of temperature compensation compared with the proprietary electrodes currently available. A judicious choice of buffer and inner reference element yields an electrode with almost the ideal characteristics of isopotential pH (=7) and zero-point pH (=7), which enable it to be used with all pH meters. Other electrodes could readily be used with modern microprocessor-based meters. In other aspects of their performance (slope factor, hysteresis, response time) the new electrodes are at least as good as commercial sensors.