Determination of cadmium in mussels by flame atomic absorption spectrometry with preconcentration on a chelating resin in a flow injection system

A flow injection preconcentration system with a chelating resin was developed to determine trace and ultratrace amounts of cadmium in mussels by flame atomic absorption spectrometry. The metal was preconcentrated on a minicolumn packed with poly(aminophosphonic acid) resin and eluted with dilute hydrochloric acid into the nebuliser-burner system of an atomic absorption spectrometer. A preconcentration factor of 16-47, equivalent to 3.4-10 ml of sample, was achieved by using a time-based technique. The detection limit (3 sigma) in the sample digest was 0.56 mu g l(-1) for a sample volume of 3.4 ml, The precision (relative standard deviation) obtained for different amounts of cadmium mas in the range 1.4-6.6% at the 1-20 mu g l(-1) level, Chemical and flow variables, and other figures of merit of the proposed methodology, were studied. The method demonstrates high tolerance to interferences, and the analytical results obtained for a certified reference material mere in good agreement with the certified value. The method was successfully applied to the determination of trace amounts of cadmium in mussel samples from estuaries in Galicia (Spain).