A new method for the simultaneous determination of copper and gold was developed by derivative spectrophotometry using a previous preconcentration on solid phase. The method is based on the formation of Cu(II)-PPDOT and Au(III)-PPDOT complexes that are extracted from aqueous solution in only 20 min on cationic exchange SP Sephadex C25. In this simultaneous determination, the second derivative and the zero crossing method were used. The copper and gold determinations were carried out at 278.0 nm and 282.0 nm, respectively. The determination range for both analytes was 1.6 x 10(-8)-141 x 10(-8) mol L-1. Good levels of repeatability (RSD) of 1.3% and 1.4% were observed for copper and gold, respectively. The method was applied successfully for the copper and gold determination in mineral residuals, minerals and natural water samples. The results were consistent with those provided by ICP-mass spectrometry. (c) 2007 Published by Elsevier Ltd.