IntroductionAt present, water quality monitoring for heavy metal con-taminants is usually handled by costly and relatively complexinstruments such as ICP-MS, GC/LC–MS, and AAS [1]. These instru-ments provide a high level of performance in terms of sensitivityand selectivity but require operation by trained personnel, usually
in a central laboratory [2]. This approach also relies on selected“grab sampling” where samples are collected on-site and thentransported to the lab for analysis. The result, of course, is a “snap-shot” of the water quality at a particular time and place which maynot be representative of other times and places in the over-all sys-tem. Alternatively there are numerous portable instruments, oftenelectrochemical in nature, which permit measurements to be madein the field [3–7]. This is a promising approach, particularly in viewof the rapid advances in fabrication of micro total analysis systems[8]. However, these are normally operated by a suitably trainedtechnician and still offer the same type of periodic “snapshot” moni-toring provided by the grab sampling approach. This is an importantlimitation, and clearly it would be desirable to develop a sensingsystem that enables continuous, on-site operation on a 24/7 basiswith minimal direct operator intervention.