ABSTRACT
Calibration refers to the process by which the response of an analytical system is related to standards with known composition. Instruments used for field tests should be calibrated prior to the field trip, and in the field before taking the measurement. Calibration of field instruments should be performed on a regular basis, and all records should be kept in a calibration log. Each maintenance or repair of a field instrument must be documented in the maintenance logbook. Measurement of pH is one of the most important and frequently used tests in water chemistry. A more accurate reading is possible by using a comparator, accompanied with a pH disc. A pH meter functions by measuring the electric potential between two electrodes that are immersed into the solution of interest. Conductivity is the numerical expression of the ability of an aqueous solution to carry an electric current.
