Determination of trace metals in natural waters by flame atomic absorption spectrometry following on-line ion-exchange preconcentration

An on-line column preconcentration technique for flow-injection flame atomic absorption spectrometry has been developed for the determination of trace metals in natural waters. A minicolumn (20 mm × 2 mm i.d.) filled with a poly(aminophosphonic acid) chelating resin (PAPhA, 20–30 mesh) was used for the preconcentration procedure. For 2 ml samples, detection limits of 0.5, 5.0, 1.5, 1.6, 3.5, 0.6, 3.2, 3.1 and 0.4 μg 1−1 for Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, respectively, were achieved. The precision (coefficient of variation) obtained was in the range between 1.1 (Cd and Cu) and 3.3% (Co). Accuracy was also investigated and results agreed with the certified values of the reference material. The sampling rate was 48 h−1. The method was applied to the determination of trace metals in natural waters samples from Galicia (Spain).