smartphone-based colorimetric method for determination of water solutions ph

Abstract: due to the importance of ph measurement in different aqueous environments and its effects on living creatures [1-3], the aim of this study is to present a new, simple, sensitive, and inexpensive analytical method, smartphone-based colorimetry, for ph measurement in water samples. in other hand, smartphone-based analysis has recently emerged as useful tool, and it has been found to be promising in several fields including point-of-care analysis [4-6]. in this work, an android application for measurement of ph determination is presented. an optical sensor, based on the natural pigments (echium amoenum anthocyanin’s) doped on the agarose-gel substrate, was designed and used to measure ph in different aqueous samples. the extracted anthocyanin from e.amoenum (eae) solution exhibited good color variations when exposed to ph 2 to ph 12. the effective variables, which affect the sensor response, include pigment concentration, temperature, shaking rate and stirring time in the extraction of the pigments, the amount of doped pigment, and the casting and molding type of the monolith are studied and optimized. the response times of the eae doped sensor obtained in less than 20 seconds and linear ranges are obtained in the ph range of 2.00 to 12.00 respectively. the relative standard deviation of the sensor with seven repetitions is less than 1%. the designed sensor's performance has been evaluated by comparing the experimental data with the commercial-grade ph-sensing tool. the results confirm good use of a mobile phone as an analytical instrument in ph determination.