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.　Copyright　©　(2018)　by　Chemical　and　Biological　Microsystems　Society.　All　rights　reserved.