Total dissolved iron and hydrogen peroxide determination using the PhotoMetrixPRO application: A portable colorimetric analysis tool for controlling important conditions in the solar photo-Fenton process

Highlights: • PhotoMetrixPRO was validated for monitoring total dissolved iron and H₂O₂. • Easy determinations of iron and H₂O₂ in loco during the experiments. • Control of parameters in the photo-Fenton process using portable device. • Rapid analysis, smaller sample volumes, greater portability and accessibility. -- Abstract: The use of the solar photo-Fenton process for water treatment requires monitoring of the main conditions, especially the total dissolved iron concentration and the consumption of hydrogen peroxide. In this study, a new methodology using the PhotoMetrixPRO application was validated for rapid monitoring of total dissolved iron and hydrogen peroxide concentrations, and was tested in the solar photo-Fenton process. A comparison was made between the results obtained using a reference spectrophotometric method and the PhotoMetrixPRO application employing a portable device. Both methods were validated in terms of linearity, sensitivity, precision, robustness, and matrix effects. The degree of dispersion between the series of measurements obtained using UV–vis and portable device tool was low and was in compliance with the established Brazilian and ICH validation criteria. Additionally, PhotoMetrixPRO enabled the use of a smaller sample volume. The total volume generated of each sample is 1 mL, reducing 6 and 10 times the wastes produced in different validated methods. These results evidencing that the miniaturization can provide positive advantages in terms of simplicity, cost effectiveness, and less environmental impact. PhotoMetrixPRO offers significant advantages including rapid analysis, smaller sample volumes, and greater portability and accessibility.