On-line preconcentration of lead and cadmium for flame atomic absorption spectrometry using a flow-through electrochemical microcell

A method was developed for the trace determination of lead and cadmium by flame atomic absorption spectrometry (FAAS) with electrochemical preconcentration. Both metals were deposited on the glassy-carbon electrode in a flow-through microcell of volume 3 μl. At a consumption of a 3 μl sample volume, the procedure resulted in an enhancement factor of more than 20 and yielded a detection limit of 1 μg l −1 for Pb and 0.08 μg l −1 for Cd. The relative standard deviation ( n=12) was 2.1% at the 100 μg l −1 level for Pb and 3.2% at the 8 μg l −1 level for Cd. Results obtained for the standard reference material, water SRM 1643c, were in good agreement with the certified values.