A miniaturized lab-on-chip system for the measurement of nitrate in water

Nitrate pollution caused by overfertilization and urban waste is a significant problem with effects on health and the environment. For improved insights into the nitrogen cycle in soil, it is necessary to monitor nitrate concentrations in water with a higher measurement rate than possible with ex-situ lab analysis. Using the Griess assay together with a lab-on-chip system is an established way to build a reliable and accurate sensing device. In this work, a compact, automated lab-on-chip system architecture using a single peristaltic pump for liquid movement is presented. We demonstrate the capability to measure varying nitrate concentrations in a range from 0 to 50 mg/l. Observed outliers are analyzed and linked to inaccuracies in the mixing of the assay chemical compounds.