Development of Automated On-site Analysis Method Using a Smart Device as Detection System for Autocatalytic Reactions

The autocatalytic reaction shows a dynamic color change after a certain induction period. In addition, the induction period of the reaction changes depending on the concentration of substances. Therefore, by using an autocatalytic reaction, it is possible to quantify by measuring the time with the human eye and a stopwatch. This method enables visual measurement with higher sensitivity and accuracy than the visual measurement method based on the conventional colorimetric method. However, it is necessary to keep observing the solution at all times during the measurement. In this study, we attempted to automate an analysis with a autocatalytic reaction using a smart device by developing an application software that automatically measures the induction period of the autocatalytic reaction. In this paper, the analytical performance was evaluated using a method for measuring the concentration of iron(II) ions by an autocatalytic reaction with sulfite and hydrogen peroxide. As a result, iron ion could be automatically determined with the proposed method. Moreover, this proposed method could be utilized under several kind of conditions, such as various distance, irradiation levels, and temperature.