Two precursors of bismuth film - Bi2O3 and Bi(III) ions - and a favorable orientation of the magnetic field were exploited to increase the Zn signals recorded at screen-printed electrodes modified with a bismuth layer. When using this configuration and an in-situ procedure, Zn(II) signals were better shaped and much more sensitive than those obtained for conventional bismuth-modified screen-printed electrodes. The developed procedure exhibits linear behavior from 4 to 199 mu g l(-1) Zn(II) with satisfying reproducibility (5%) and an low LOD of 0.05 mu g l(-1). The method was applied for the determination of Zn(II) in fly ash extracts and mineral waters. (C) 2015 Elsevier Ltd. All rights reserved.