Low-cost Detection of Nitrite in Water with µPADs Running the Griess Reaction
Authors:Ngan Phan, Sate Sukserm
Mentor:Roger C. Lo, Assistant Professor and Graduate Advisor, Department of Chemical Engineering, California State University, Long Beach
Excessive nitrite present in the water supplies can have adverse effects on both humans and animals, such as methemoglobinemia, which reduces the blood’s capacity to carry oxygen and can be lethal at a high concentration. Furthermore, nitrite has been shown to be a precursor to the formation of N-nitroso compounds, most of which are carcinogenic to animals and humans. Nitrite found in water can come from fertilizer contamination and inappropriate waste disposal. As a result, there is a pressing need for cost-effective, simple-to-operate systems for water quality assays in an industrialized environment. Herein, we report a low-cost and simple-to-operate microfluidic paper-based analytical device (µPAD) for measuring the concentration of nitrite in water samples from the Ports of Los Angeles and Long Beach. The µPADs were fabricated by printing chips designs on chromatography paper using a commercial wax printer. They use capillary forces to transport the liquid contents and require no external components (such as a pump) for fluid manipulations. This feature can significantly simplify the instrument design and reduce the energy consumption for continuous operations. After optimization, these devices can be operated by personnel with the minimal amount of training and thus can be easily deployed to areas that lack laboratory infrastructures.