SIMPLE FLOW INJECTION TITRATION METHOD BASED ON VARIATION OF THE SAMPLE VOLUME

Abstract

ABSTRACT A simple single-line flow injection system incorporating the fully rotary valve (FRV) has been developed for titration purposes. The FRV enables to inject the titrand solution to the titrant stream in four different volumes producing a set of four adequate analytical signals. Due to this fact the titration procedure can be performed with the use of only two standard solutions which allow four parallel calibration lines to be constructed. The method was tested on the example of spectrophotometric acid–base titration. Under optimised flow conditions (flow rate of 8.3 mL/min, the volumes injected of 30, 100, 300, and 800 µL, titrant containing 0.1 mmol/L NaOH and 4 × 10−4% bromothymol blue) the analytical results of precision less than 0.6% (RSD) and of accuracy less than 0.5% (relative error) were obtained for the HCl samples of pH ranged from 1 to 2.