Abstract
This work reports the fabrication of a new environmentally friendly three-electrode electrochemical sensor suitable for on-site voltammetric determination of two toxic emerging ‘technology-critical elements’ (TCEs), namely indium and thallium. The sensor is fully fabricated by injection-moulding and features three conductive polymer electrodes encased in a plastic holder; the reference electrode is further coated with AgCl or AgBr. The sensor is applied to the determination of trace In(III) and Tl(I) by anodic stripping voltammetry using a portable electrochemical set-up featuring a miniature smartphone-based potentiostat and a vibrating device for agitation. For the analysis, the sample containing the target metal ions is spiked with Bi(III) and a bismuth film is electroplated in situ forming an alloy with the accumulated target metals on the working electrode of the sensor; the metals are stripped off by applying a square-wave anodic voltametric scan. Potential interferences in the determination of In(III) and Tl(I) were alleviated by judicious selection of the solution chemistry. Limits of quantification for the target ions were in the low μg L−1 range and the sensors were applied to the analysis of lake water samples spiked with In(III) and Tl(I) with recoveries in the range of 95–103%.
Highlights
Indium and thallium belong to the group of “energy-critical elements” or “technologycritical elements” (TCEs); TCEs are elements that had no significant previous industrial role but whose current industrial use is growing rapidly since they are key components in the development of new technologies [1,2,3]
TCEs are considered as emerging contaminants and their environmental footprint from anthropogenic and industrial activities should be carefully controlled [4,5]
The deposition of a bismuth film on the conductive polymer working electrode was examined by optical microscopy
Summary
Indium and thallium belong to the group of “energy-critical elements” or “technologycritical elements” (TCEs); TCEs are elements that had no significant previous industrial role but whose current industrial use is growing rapidly since they are key components in the development of new technologies (information and telecommunications technology, semiconductors, electronic displays, optic/photonic and energy-related technologies) [1,2,3]. TCEs are considered as emerging contaminants and their environmental footprint from anthropogenic and industrial activities should be carefully controlled [4,5]. Spectroscopic techniques are the “golden standard” for the determination of trace concentrations of indium and thallium [12,13]. Stripping analysis offers a viable alternative to spectroscopic methods due to its lower cost, rapidity, portability, sensitivity and scope for on-site analysis. The large majority of stripping methods for In and
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