Multiplex quantification of metals in air PM via smartphone and μPADs

In this paper, by integrating microfluidic paper-based analytical devices (μPADs), smartphone colorimetric detection and mobile sample collection, we present a portable system for multiplex quantification of trace metals concentrations. Relying only on cellphone photography, and a self-developed iOS app, our system allows for multiplex quantification of up to 6 metals (Co, Cu, Fe, Mn, Cr and Ni) by automatically analyzing colorimetric assay images in an arrayed format. This reduces the analysis time, simplified the quantification process and improved the assay throughput, thus making the approach potentially well-suited for disposable on-site analysis.