Preconcentration and flame atomic absorption spectrometry determination of cadmium in mussels by an on-line continuous precipitation–dissolution flow system

A rapid, sensitive, accurate and precise flame atomic absorption method is described for the determination of cadmium in mussels. The method is based on the continuous precipitation of cadmium as an ion pair between tetraiodocadmate and quinine and dissolution of the precipitate with ethanol. The metal can be preconcentrated 32-fold using 15 ml of sample solution by using a time-based technique at a sampling flow rate of 3.0 ml min−1. The proposed method allows the determination of cadmium in the range 0.25–5.5 μg g−1. The precision (relative standard deviation) obtained for different amounts of cadmium is in the range 1.5–4.7% at the 0.25–5.0 μg g−1 level. The method demonstrates high tolerance to interferences, and the data obtained are in agreement with the certified value of a selected reference material. This procedure was applied to the determination of cadmium in mussel samples from estuaries in Galicia (Spain).