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

• Published in: Analytica chimica acta 1999-09, Vol.396 (1), p.91-97
• Main Authors: Honorato, Ricardo S., Araújo, Mário César U., Lima, Ricardo A.C., Zagatto, Elias A.G., Lapa, Rui A.S., Costa Lima, José L.F.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemical and thermal methods; Chemistry; Exact sciences and technology; Fibonacci method; Flow analysis; Flow-batch titrator; Spectrophotometry; Wines
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/S0003-2670(99)00366-9

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. 0.6ml of sample and titrant are consumed per determination. Within the 5.2–7.3gl−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