A method was developed to attach 4-amino-2-mercaptopyrimidine (AMP) onto silica gel surface and to determine trace metals. The Surface functionalization reaction was performed with a silylant agent, chloropropyltrimethoxysilane (Si-CPTS), and the product, Si-AMP, was characterized by FT-IR and elemental analysis to evaluate the Surface modification. The functionalized silica was applied in the sorption of Cu(II) ions from an aqueous medium. The series of adsorption isotherms were adjusted to a modified Langmuir equation and the maximum number of moles of adsorbed copper was 0.447 mmol g(-1). The modified material was placed in a preconcentration system, where it reached ail approximately 20-fold enrichment factor using 5 mg of Si-AMP. The proposed method was applied in the preconcentration and determination of Cu(II) in a fresh water sample from the Parana river and was validated through a comparative analysis of a standard reference material (1643 e). (C) 2009 Elsevier B.V. All rights reserved.