DOI: 10.1039/c2an36402f

We report on the selective absorbance detection of mercury(II) and lead(II) ions using ferrocene-based colorimetric ligands and miniaturized multiple internal refection (MIR) systems implemented in a low cost photonic lab on a chip (PhLoC). The detection principle is based on the formation of selective stable complexes between the heavy metal ion and the corresponding ligand. This interaction modulates the ligand spectrum by giving rise to new absorbance bands or wavelength shifting of the existing ones. A comparative study for the detection of Hg²⁺ was carried out with two MIR-based PhLoC systems showing different optical path lengths as well as a standard cuvette. This microsystem was also applied for the detection of Pb²⁺ achieving a high sensitivity. Such a simple analytical tool could be implemented in portable instruments for automatic in-field measurements and, considering the minute sample and reagent volume required, would enable the deployment of high throughput environmental analysis of these pollutants and other related hazardous species.