Desarrollo de un analizador ambiental basado en un smartphone y su aplicación para la detección de fosfatos en muestras acuosas

Abstract

Eutrophication can cause a series of problems in aquatic ecosystems and have negative impacts on both the environment and society. Therefore, monitoring this phenomenon is key to maintaining water quality. Additionally, there is currently considerable interest in the development of portable devices for the analysis of environmental samples. A particularly promising and widely reported approach is the use of smartphone-based sensors due to the ubiquity, accessibility, and connectivity of these devices. Therefore, the objective of this research is to develop a prototype of an environmental analyzer based on digital colorimetry, as well as to evaluate its functionality in determining the concentration of phosphates in aqueous media, to serve as a tool for the early detection of potential eutrophication processes. The samples evaluated come from an experimental aquaculture at the Universidad Santo Tomás Seccional Bucaramanga, located in the municipality of Piedecuesta, Santander. A smartphone (Xiaomi POCO X3) integrated with a custom-made dark cover and a luminic base was used for the colorimetric analysis. Subsequently, the digital processing of the obtained images was carried out by extracting the RGB color space coordinates using the open-source software ImageJ. The results obtained using the proposed colorimetric system were validated with a conventional UV-Vis spectrophotometer (Cary 60, Agilent). It was found that the determination of phosphates in the analyzed samples showed statistically similar values using both methods. Additionally, both systems were compared in terms of their precision, accuracy, linearity, sensitivity, detection limit, and quantification limit. The linearity and precision of the measurements performed with the proposed environmental analyzer, along with its practicality, portability, and low cost, demonstrates its applicability for the determination of phosphates in aqueous samples, and highlights the considerable potential of using this device for other colorimetric determinations. Therefore, it is expected that the results of this research will stimulate future approaches for the analysis of environmental samples using digital photometry.