A smart-phone-based electrochemical platform with programmable solid-state-microwave flow digestion for determination of heavy metals in liquid food.

This work introduces an inexpensive and user-friendly electrochemical platform for heavy metal determination in liquid food. Smart-phone connectivity, solid-state-microwave flow digestion and nano-Au-modified electrode are synchronously studied. A smart phone is adopted as the information terminal for universal purposes. A solid-state-microwave digestion device is developed to provide programmable digestion for liquid food in a digestion path. Microwave power curve and flow rate in digestion are studied and optimized. A nano-Au-modified electrode, as well as a homemade potentiostat and other electrodes, is used as a tool for electrochemical analyses. Behaviors of this method are evaluated with electrical measurement and stripping voltammetry. This method is used for sensing Cd, Pb and Hg in cow milk, orange juice and apple juice. It provides a sensitive response to ≥2 μg L target ion, and shows satisfying stability and good accuracy in a task up to 72 h.