The analysis of cadmium in marine samples

This paper describes a procedure for extracting cadmium from seawater and from whole-organism digests of the gastropod mollusc Mytilus planulatus (common mussel) prior to analysis by atomic absorption spectrophotometry (AAS). The individual whole mussels were dehydrated to constant weight at 50 degrees C, digested under simple reflux in nitric acid, and the solution buffered to pH 5 with sodium hydroxide and sodium citrate. The cadmium was extracted into dithizone in methyl isobutyl ketone and the organic layer stored in polyethylene containers for analysis by AAS. Seawater samples were treated in the same way, without dehydration. At each step in the sample preparation, the method was tested to ensure that no significant loss or contamination had occurred.