About the Seminar:

Higher levels of phosphates in surface water are a significant concern as they cause the eutrophication of freshwater systems. Traditional phosphate monitoring methods require complicated, heavy instrumentation and labor-intensive methods and are usually expensive. An alternative is paper-based microfluidics (µPADs) because they are inexpensive (<$1), fast (<10min assay time), user-friendly, and biodegradable. Current approaches using µPADs involve quantifying color signals from Phosphomolybdenum Blue (PMB) reaction where phosphate ions react with Mo(VI) under acidic conditions to form the Keggin ion, which is subsequently reduced to form a blue-colored PMB product. However, current platforms require pipetting a fixed sample volume into the assay cards. In addition, they also require adding sulfuric acid at the time of detection. These requirements make current platforms impossible to be used by untrained users due to assay complexity and requirements for handling toxic reagents in resource-limited settings. In this study, a mPAD combined with a smartphone application was used to quantify the color formation within the assay time of 3 minutes with a limit of detection of 3ppm with only a single sample addition step. The device was stable and free of interference, making it applicable in real-world settings. The device was delivered to the volunteers across Europe, and data was validated using a gold standard UV-Vis method, showing that the results were consistent and comparable. This technique is pertinent in transitioning from a instrument-based lab technique to inexpensive and user-friendly methods to monitor phosphate levels in the freshwater.