A flow-batch titrator exploiting a one-dimensional optimisation algorithm for end point search Original Research Article

A flow-batch hybrid system is proposed as a novel approach to automated titration. Sampling and signal processing are done as in usual flow systems, whereas chemical reactions take place in a reaction chamber similar to those found in batch systems. End point is found by means of the Fibonacci method, adapted to act as a one-dimensional optimisation algorithm for fast titration. A model system involving the spectrophotometric NaOH/HCl titration was initially studied, and the feasibility of the approach was further demonstrated in the titration of white wines with NaOH using m-cresol purple as indicator. About 20 samples are run per hour and ca. 0.6 ml of sample and titrant are consumed per determination. Within the 5.2–7.3 g l−1 acidity (expressed as tartaric acid) range, relative standard deviations of results were estimated as about 0.7% after six-fold processing of typical wine samples, and results are in agreement with those obtained by a classical potentiometric titration, with relative errors <0.8%.