Determination of water pH using absorption-based optical sensors: evaluation of different calculation methods

Abstract

Absorption-based optical sensors have been developed for the determination of water pH. In this paper, based on the preparation of a transparent sol–gel thin film with a phenol red (PR) indicator, several calculation methods, including simple linear regression analysis, quadratic regression analysis and dual-wavelength absorbance ratio analysis, were used to calculate water pH. Results of MSSRR show that dual-wavelength absorbance ratio analysis can improve the calculation accuracy of water pH in long-term measurement.