No abstract

A variety of recent developments and applications of electrogenerated chemiluminescence (ECL) for sensors are described. While tris(2,2′-bipyridyl)-ruthenium(II) and luminol have dominated and continue to pervade the field of ECL-based sensors, recent work has focused on use of these lumophores with micro- and nanomaterials. It has also extended to inherently luminescent nanomaterials, such as quantum dots. Sensor configurations including microelectrode arrays and microfluidics are reviewed and, with the recent trend toward increased use of nanomaterials, special attention has been given to sensors which include thin films, nanoparticles and nanotubes. Applications of ECL labels and examples of label-free sensing that incorporate nanomaterials are also discussed.

To more readily evaluate the complex biogeochemistry of selenium, a flow-through electrochemical method was developed that can accurately determine Se(IV) concentrations in aqueous samples to part-per-trillion levels without signal calibration. Stripping methods were used in conjunction with a high-efficiency, flow-through cell. The cell was designed with a novel gold working electrode that was separated from a porous counter electrode by a Nafion membrane. Because this design permitted exhaustive deposition of selenium from the sample stream as well as efficient coulometric stripping, determinations obeyed Faraday's law over a reasonably wide range of operating conditions. The method had a minimum quantitation limit of approximately 8 ng and a maximum limit of 800 ng for Se(IV). It was reliable for sample volumes as small as 0.5 mL and as high as 20 mL, thereby allowing determinations from part-per-million to just below part-per-billion levels. Interferences from Cu(II) and arsenate were evident, but only when these species were present at concentrations exceeding 10 mg.L-1. Overall, the method had a performance comparable to hydride-generation atomic absorption spectrometry but with less cumbersome equipment and freedom from calibration.