Abstract: In the measurement of ion concentration, a selected base is added to the sample liquid which reduces the hydrogen ion content without producing other cations of a size to which the measuring electrode is sensitive. Bases having a high molecular weight and a dissociation constant, particularly secondary and tertiary amines are suitable for us. The system includes an absorber which mixes sample liquid with gaseous base, means for pressurizing the reference electrode, and an analyzer cell which prevents contamination of the measuring electrode with reference fluid leaking from the reference electrode. A separate reservoir mixes known concentration solutions for calibration purposes. The concentration readout meter of the system includes an auxiliary dial for ease of calibration.