Fabrication of paper-based devices by lacquer spraying method for the determination of nickel (II) ion in waste water.

A spraying method with lacquer was developed for the fabrication of paper-based devices. A patterned iron mask was initially placed on a filter paper and held tightly attached by a magnetic plate placed on the opposite side. After that, acrylic lacquer was sprayed on the filter paper to create a hydrophobic area while the hydrophilic area was protected with the iron mask. The optimal conditions for the fabrication of this device were studied including lacquer type and particle retention efficiency of filter paper. Gloss spray lacquer and filter paper No. 4 were chosen as optimal lacquer type and particle retention efficiency of filter paper, respectively. To evaluate its efficiency, the paper-based devices were used to determine nickel using electrochemical detection. Cu-enhancer solution was employed to increase sensitivity of nickel determination with the optimal concentration of 4.5 ppm. Under the optimal conditions, linear range was observed in the range of 1-50 ppm with a coefficient of determination of 0.9971. The limit of detection (LOD) and the limit of quantitation (LOQ) were found to be 0.5 and 1.97 ppm, respectively. Moreover, these paper-based devices coupled with electrochemical detection were applied to determine nickel in waste water of a jewelry factory and compared to those obtained with inductively coupled plasma optical emission spectrometry (ICP-OES). The results indicated that there were no significant variations between this proposed method (4.15±0.043 ppm) and the ICP-OES method (4.06±0.013 ppm). Therefore, this spraying method was found to be an excellent alternative for the fabrication of paper-based devices due to its ease of use, affordability and simplicity.