Flow injection method for preconcentration and polarographic determinationof copper in water

The analytical application of a simple polarographic Row through cell, whic h was previously designed for the continuous polarographic analysis of orga nic compounds in pharmaceuticals and urine, is proposed in this work for th e determination of copper in diluted water samples. The cell contains a con ventional dropping mercury electrode (DME), a mercury pool and a platinum w ire as the working, reference and counter electrodes, respectively Enrichme nt of the analyte, previous to the polarographic continuous determination. was necessary and was achieved by using a microcolumn containing Chelex-100 , located in the loop of the injection valve. The Row through detector can be used either amperometrically, under continuous Row operation, or voltamm etrically in quiet solution. under continuous flow-stopped flow mode. Under continuous Row operation of the cell, after a preconcentration rime of 3 m in, the preconcentration factor was calculated to be 90. with a limit of de tection of 9.5 ng/ml and a sampling rate of 15 h(-1). The repeatability of the analytical signals, expressed as RSD, was always lower than 2.1%. Valid ation of the method was carried out by analysis of certified reference mate rials, and the recovery was 101.96 +/- 1.38%.