pH Testing
 

The pH meter requires 3 electrodes: a pH sensitive electrode, a reference electrode, and a temperature-compensating electrode.  The pH sensitive electrode is required to measure the ambient electrical potential present.  To compensate for this, a temperature-compensating electrode is installed to offset the influence of temperature.  These 3 electrodes are usually mounted in an electrode chamber for installation in a sample line or submerged in a tank, pond, or channel.  Modern pH metering systems are often provided with signal preamplifiers installed within the electrode assembly to minimize electrical noise pickup in the high-impedance electrical circuits.  Also, reference electrodes are now available for most applications, which eliminates the need for electrolyte applications, which eliminates the need for electrolyte needed in conventional reference electrodes of the flowing junction type.  The accuracy of pH analyzers is in the range of 0.1 (+ or - 0.05).