A stack-up electrochemical device based on metal-organic framework modified carbon paper for ultra-trace lead and...

A portable device is conducive to the on-site detection of heavy metal ions at trace level in food and the prevention of related food safety issues. In this work, an electrochemical device stacked up with flat electrodes was developed for the detection of Pb²⁺ and Cd²⁺. The top layer of the device is a carbon paper as working electrode, which is modified with amino functionalized cobalt-based metal-organic framework and gold nanoparticles. The bottom layer was constructed with the carbon counter electrode and Ag/AgCl reference electrode, and a punched sample cell (Φ = 8 mm) was in the middle. The proposed method could simultaneously determinate Pb²⁺ and Cd²⁺ via anodic stripping voltammetry with the detection limit of 7.0 × 10^-2 ng mL^-1 and 1.1 × 10^-2 ng mL^-1, and was applied in real food samples (drinking water, juice, tea, grain, fruits, vegetables, liver and aquatic products) with the recovery of 91.2-105.4 % and 90.2-111.2 %, respectively.