Bioaccumulation And Quantitation Of Metals At Peat Moss-Modified Electrodes

Plant materials of the genus Sphagnum have long been known to absorb cations preferentially from dilute solutions. Preconcentrating modified electrodes, based on the incorporation of peat moss within carbon paste matrices, have been designed for bioaccumulating copper ions prior to their voltammetric quantitation. Operational conditions, such as paste composition, solution pH or ionic strength, accumulation time, and voltammetric waveform are characterized and optimized to allow quantitation of submicromolar concentrations. The surface is regenerated by placing the electrode in a hydrochloric acid solution, allowing the use of a single electrode in multiple determinations (RSD of 6% for 15 repetitions). The plant modifiers also strongly bind and retain multiple charged counterions. These surface-bound ionic metal complexes are able to mediate electron transfer with solution species (such as hydrogen peroxide). The approach could be extended to other plant-material modifier/analyte systems, as well as for preconcentration for other trace techniques. Preliminary data are given for the Spanish moss/silver system.