Electrical conductivity has been measured using EC meters for many years and it is still an important and widely used analytical parameter today. In-line EC meters, also called conductivity analyzers, offer an easy and economical way to provide an indication of the conductivity of the measured medium. The excellent reliability, sensitivity, response and relatively low cost of a conductivity analyzer makes conductivity a valuable, easy-to-use tool for quality control. In some applications, the purity measurement is made as resistivity (the reciprocal of conductivity).