Colorimetric microfluidic paper-based sensor for determination of nitrite in drinking water with enhanced color development

Abstract

A low cost colorimetric microfluidic paper-based analytical device (µPAD) for the determination of nitrite in real samples with improved precision has been fabricated and its performance has been evaluated. The µPAD was fabricated by laser cutting and patterning on the paper and the nitrite concentration measurement is based on the modified Griess assay. In this assay, tartaric acid was used as an antioxidant reagent to increase Griess reagent stability. A novel geometrical design was used to achieve better color gradient over µPAD detection zone for improving the precision of the measurements. The results of measurement indicate that the fabricated device could successfully detect and quantify the nitrite concentration in real samples with the limit of detection (LOD) of 15 μM. The results are in good accordance with the results of spectrophotometry. The fabricated sensor has the potential to be applied for monitoring of the trace level of nitrite in drinking water and environmental applications.