A new method has been developed separation and preconcentration with biomaterial for the determination of trace cadmium based on eggshell membrane (ESM) prior to its determi- nation by graphite furnace atomic absorption spectrometry. The optimum experimental parameters for preconcentration of cadmium, such as ammonia medium, sample flow rate and volume, eluent and interfering ions, have been investigated. Cadmium could be quantitatively retained by ESM in the concentraton range of 0.1--2.0 mol/L ammonia solution, and then eluted completely wi...