Precipitation titrations using an automatic titrator based on a multicommutated unsegmented flow system

An automatic flow titrator based on a multicommutated unsegmented flow syst em was used to perform precipitation titrations with potentiometric detecti on. The titration approach is based on sequential introduction of increasin g titrant and decreasing titrand volumes into a mixing chamber. The system allows the attainment of complete curves, the titration end point being det ermined by the Gran method, as is usually employed in batch potentiometric titrations. The theoretical model for the analytical process is presented a nd discussed and the determination of titrand concentration is performed wi thout any prior calibration. The automatic flow titrator developed was appl ied to chloride determination in bottled natural waters and the results obt ained were reproducible (RSD 3.2 and 3.8% for repeatability and reproducibi lity, respectively) and in good agreement with those given by the reference procedure (relative deviation within the range from -4.6 to 4.8%).