Abstract
Lab-on-paper technologies, also known as paper-based analytical devices (PADs), have received increasing attention in the last years, and nowadays, their use has spread to virtually every application area, i.e., medical diagnostic, food safety, environmental monitoring, etc. Advantages inherent to on-field detection, which include avoiding sampling, sample preparation and conventional instrumentation in central labs, are undoubtedly driving many developments in this area. Heavy metals represent an important group of environmental pollutants that require strict controls due to the threat they pose to ecosystems and human health. In this overview, the development of PADs for Hg monitoring, which is considered the most toxic metal in the environment, is addressed. The main emphasis is placed on recognition elements (i.e., organic chromophores/fluorophores, plasmonic nanoparticles, inorganic quantum dots, carbon quantum dots, metal nanoclusters, etc.) employed to provide suitable selectivity and sensitivity. The performance of both microfluidic paper-based analytical devices and paper-based sensors using signal readout by colorimetry and luminescence will be discussed.
Highlights
Well-known cases concerning Hg poisoning include the consumption of seeds contaminated with this kind of fungicides (Iraq, 1971) [3] or the Minamata accident (Japan, 1953) [4] due to the intake of fish contaminated with methylmercury, which was formed by biomethylation of inorganic Hg released in the bay
For the determination of Hg at thetrace level, conventional instrumentation is typically used in central labs on a routine basis, such as cold vapor-atomic absorption spectrometry (CV-AAS) [12], cold vapor-atomic fluorescence spectrometry (CV-AFS) [13], electrothermal atomic absorption spectrometry (ETAAS) [14], inductively coupled plasmamass spectrometry (ICP-MS) [15] and total reflection X-ray fluorescence (TXRF) [16]
We provide an overview on the state of the art of paper-based analytical devices (PADs) for the detection hough several review papers have appeared in the literature dealing with applicat of Hg in environmental samples, their main shortcomings and future prospects
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. For the determination of Hg at the (ultra)trace level, conventional instrumentation is typically used in central labs on a routine basis, such as cold vapor-atomic absorption spectrometry (CV-AAS) [12], cold vapor-atomic fluorescence spectrometry (CV-AFS) [13], electrothermal atomic absorption spectrometry (ETAAS) [14], inductively coupled plasmamass spectrometry (ICP-MS) [15] and total reflection X-ray fluorescence (TXRF) [16] While these techniques provide adequate sensitivity and precision, they require suitable sampling, preservation procedures, sample pretreatment and a fully controlled laboratory environment, which makes it difficult to extend their application for on-field analysis [17]. Further appealing features include the possibility of performing temporally and spatially discriminated analysis and the access to remote sites so that the source of pollutants, their distribution and environmental impact can be more assessed [19]
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