2021 Volume 70 Issue 6 Pages 379-383
We developed a sensitive determination of hexavalent chromium (Cr(VI)) using a microfluidic paper-based analytical device (μPAD) by solid-phase extraction with a highly selective resin cartridge. This resin (MetaSEP AnaLig Cr-02), which could selectively adsorb Cr(VI) was used as the preconcentration of Cr(VI) for the sensitive analysis. The diphenylcarbazide (DPC) colorimetry was utilized for a Cr(VI) assay. After solid-phase extraction was carried out, the eluent was dropped to the sample zone of the μPAD added with DPC solution. The intensity of detection zone image for the colored μPAD was analyzed with the image processing software to determine Cr(VI). The effect of the sample volume on the intensity was investigated, the intensity linearly increased with the sample volume. The concentration of Ba(II), Ca(II), Cu(II), Fe(III), Mg(II), Ni(II), and Pb(II) was 10 times higher than that of Cr(VI), but they had no effect on the determination of Cr(VI). In the range of Cr(VI) concentration from 0 to 20 μg L−1, a good linear calibration curve with a coefficient of determination of 0.9978 was obtained. The detection limit and the limit of quantification were 1.3 μg L−1 and 4.3 μg L−1, respectively. The proposed method was applied to the determination of Cr(VI) in the river water and the tap water, no influence of coexisting substances was observed, and good results were obtained.
