Calibrationless determination of cadmium, lead and copper in rain samples by stripping voltammetry at mercury microelectrodes - Effect of natural convection on the deposition step

Mercury microelectrodes were prepared by ex situ deposition of Hg onto Pt microdises. By exploiting the known properties of microelectrodes in stripping analysis, an absolute method based on a simple equation derived from the stripping charge and the microelectrode steady-state current was assessed for the simultaneous quantification of Cd2+, Pb2+ and Cu2+ concentrations. The method was tested with synthetic solutions containing known amounts of Cd2+, Pb2+ and Cu2+. Then, it was used to determine the labile and total fractions of these metal ions in rain samples. The labile fractions were measured from samples at their natural pH while the total concentrations were determined from samples at pH = 2. (C) 2002 Elsevier Science B.V. All rights reserved.