A new nanostructure which is surface-modified cobalt aluminate nanoparticles with silica is used for the separation of cadmium and lead prior to its determination by inductively coupled plasma-mass spectrometry was described. For this purpose, at first, ex-situ modification of cobalt aluminate nanoparticles was made, then lead and cadmium were collected on new sorbent by syringe technique. The effects of experimental conditions on sorption of cadmium and lead were investigated. After the optimization of experimental parameters, a successful separation and determination were obtained with high quantitative recovery (>95%) and precision (<10% RSD). Using the proposed technique, the cadmium and lead concentrations in tap water and drinking water could be practically and rapidly determined in the range of 95% confidence level. The detection limit of the described method for cadmium and lead using sample-matching blanks were 0.053 and 0.117 mu g L-1 (3 sigma, N = 10), respectively. The proposed technique was fast, simple, and economic.