Development of paper-based analytical devices for simultaneous naked-eye detection of heavy metal ions

Paper-based analytical device was fabricated by a polymer screen printing and wax printing methods. The various types of device were designed for simultaneous heavy metal ions detection in synthetic unknown and real water samples. The colorimetric method was applied to detect the heavy metal ions using 1-(2-pyridylazo)-2-naphthol, bathophenanthroline, 1, 5-diphenylcarbazide, bathocuproine, dimethylglyoxime, dithizone, and 4-(2-pyridylazo) resorcinol as complexing agents. However, complexing agents require very highly selectivity. To improve the selectivity for heavy metal ion detection, a device was designed with pretreatment zones and the masking agents were applied to remove interfering ions. The proposed method was successfully applied for simultaneous Cu(II), Co(II), Zn(II), Cd(II)/Pb(II) detection on device type D and for simultaneous Cu(II), Co(II), Ni(II), Hg(II), Fe(III), Cr(VI), V(III), and Mn(II) detection on device type E in synthetic unknown water samples by naked-eye. For simultaneous Cu(II), Co(II), Ni(II), Hg(II), and Mn(II) determination on device type F, the analytical performance was achieved with the lowest detectable concentration of 0.32, 0.59, 5.87, 0.20, and 0.11 mg/L for Cu(II), Co(II), Ni(II), Hg(II), and Mn(II), respectively. The proposed method provided highly selective and efficient for simultaneous Cu(II), Co(II), Ni(II), Hg(II), and Mn(II) determination in drinking, tap, and pond-CU water samples and detection by naked-eye.