Label-free heavy metal ion sensing via smartphone based app.

The proliferation of heavy metal ions in water has been a serious problem that has been escalating day by day. Rapid detection of these ions in an aqueous solution is of immense significance to keep them within permissible limit. To address the growing concentration of heavy metal ions, we report a facile and cost-effective sensing scheme. Based on intensity modulation, the sensing scheme comprises of a smartphone, light source, and analyte. The results reveal that the concentration of heavy metal ions can be detected at ppb level. The sensing scheme renders an average limit of detection (LOD) of ∼0.5 ppb for those assessed ions. Further, spiked tap water has also been assessed to check the applicability of the scheme which eventually yields a ∼95% recovery level. Overall, the sensing scheme with minimal logistics is believed to replace the complex analysis procedure executed through bulky and sophisticated instruments.