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

Abstract

An automatic flow titrator based on a multicommutated unsegmented flow system was used to perform precipitation titrations with potentiometric detection. The titration approach is based on sequential introduction of increasing titrant and decreasing titrand volumes into a mixing chamber. The system allows the attainment of complete curves, the titration end point being determined by the Gran method, as is usually employed in batch potentiometric titrations. The theoretical model for the analytical process is presented and discussed and the determination of titrand concentration is performed without any prior calibration. The automatic flow titrator developed was applied to chloride determination in bottled natural waters and the results obtained were reproducible (RSD 3.2 and 3.8% for repeatability and reproducibility, respectively) and in good agreement with those given by the reference procedure (relative deviation within the range from −4.6 to 4.8%).