Specific conductance; theoretical considerations and application to analytical quality control

This report considers several theoretical aspects and practical applications of specific conductance to the study of natural waters.

A review of accepted measurements of conductivity of secondary standard 0.01 N KCl solution suggests that a widely used algorithm for predicting the temperature variation in conductivity is in error. A new algorithm is derived and compared with accepted measurements. Instrumental temperature compensation circuits based on 0.01 N KCl or NaCl are likely to give erroneous results in unusual or special waters, such as seawater, acid mine waters, and acid rain.

An approach for predicting the specific conductance of a water sample from the analytically determined major ion composition is described and critically evaluated. The model predicts the specific conductance to within ?8 percent (one standard deviation) in waters with specific conductances of 0 to 600 microS/cm. Application of this approach to analytical quality control is discussed.