An aluminum hydroxide coprecipitation method for the determination of cadmium, copper and lead by flame atomic absorption spectrometry in aqueous solutions, seawater and mineral water samples has been investigated. The coprecipitation conditions, such as the effect of the pH, the amount of carrier element, the effect of possible matrix ions and the time were examined in detail for the studied elements. It was found that cadmium, copper and lead are co-precipitated quantitatively (>= 95%) with aluminum hydroxide at pH 7 with low R.S.D. values of around 2 to 3%. Detection limits (38) were 6 ng ml(-1) for Cd, 3 ng ml(-1) for Cu and 16 ng ml(-1) for Pb. The method proposed was validated by the analysis of HPS 312205 seawater standard reference material and spiked mineral water samples. (c) 2005 Elsevier B.V. All rights reserved.