Postage stamp-sized array sensor for the sensitive screening test of heavy-metal ions

Abstract

The sensitive determination of heavy-metal ions has been widely investigated in recent years due to their threat to the environment and to human health. Among various analytical detection techniques, inexpensive colorimetric testing papers/strips play a very important role. The limitation, however, is also clear: the sensitivity is usually low and the selectivity is poor. In this work, we have developed a postage stamp-sized array sensor composed of nine commercially available heterocyclic azo indicators. Combining filtration-based enrichment with an array of technologies-based pattern-recognition, we have obtained the discrimination capability for seven heavy-metal ions (Hg²⁺, Pb²⁺, Ag⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Co²⁺) at their Chinese wastewater discharge standard concentrations. The allowable detection level of Hg²⁺ was down to 0.05 mg L⁻¹. The heavy-metal ions screening test was readily achieved using a standard chemometric approach. And the array sensor applied well in real water samples.