Ready-to-use Nafion-Bi2O3 modified graphite paper/gel electrode for the detection of lead in vegetables and fruits and its anti-interference performance

Electrochemical detection has been used to measure heavy metals in food, but matrix interferences remain limited the rapid treatment-detection. This study developed a Nafion-Bi₂O₃ coating modified graphite paper/sodium alginate gel electrode to amplify the electrical signal of Pb(II) and improve the anti-interference towards organic acids and metal ions. Although negatively charged organic acids were excluded by Nafion, interferences of exchangeable ions were amplified. In the mix drip coating, Bi₂O₃ was chemical combined and electrostatic interacted with OH, SO₃⁻ and C-S in Nafion. This modification reduced diffusion resistance, enhanced surface hydrophobicity and provided additional reactive oxygen binding sites. The peak current of Pb(II) increased 56.62 % and the detection limit was lowered to 0.015 μg/L. The recoveries of Pb in matrices were 78.33 %–106.45 %. The easy field modified graphite paper electrode represents an innovation, and this study will propel the rapid detection of heavy metals based on acid-extraction.