On-line preconcentration and determination of nickel in natural water samples by flow injection-inductively coupled plasma optical emission spectrometry (FI-ICP-OES)

An on-line nickel preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry (ICP-OES) associated to flow injection (FI) was studied. Trace amounts of nickel were preconcentrated by sorption on a conical minicolumn packed with activated carbon (AC) at pH 5.0. The nickel was removed from the minicolumn with 20% nitric acid. An enrichment factor of 80-fold for a sample volume of 50 ml was obtained. The detection limit (DL) value for the preconcentration method proposed was 82 ng l−1. The precision for ten replicate determinations at the 0.5 μg l−1 Ni level was 3.0% relative standard deviation (R.S.D.), calculated from the peak heights obtained. The calibration graph preconcentration method for nickel was linear with a correlation coefficient of 0.9997 at levels near the detection limits (DL) up to at least 100 μg l−1. The method was successfully applied to the determination of nickel in natural water samples.