Colorimetric detection of Hg2+. For method development, several relatively simple procedures were followed.
First, we used a plastic dropping bottle (5 ml) as a reactor to mix the samples containing Hg(II) with the
PtNPs solution. As the Hg(II) was diluted in deionized water to specified concentrations, 2 ml of the Hg(II) sample
was added to the dropping bottle to effect rapid reaction (2 min.) with the PtNPs solution (1 ml). One drop
of reagent (ca. 10 μ L) from the dropper bottle was dispensed onto the detection zone where 10 μ l of TMB/H2O2
colorimetric substrate solution had already been placed. The paper underwent complete reaction within 5 minutes
and the colored images were captured by digital camera or smartphone and where the specific color intensity
of the paper was measured by the fiber optic device.