In this thesis,a solid phase extraction (SPE) system used for preconcentration and separation of lead(II) and cadmium(II). The Basis of this method, is preparation of Pb(II) and Cd(II) complexes with CyanuricSH modified carbonnanotubes.In our case, 110 mg of the adsorbent consist of 50 mg graphite powder, 40 mg CyanuricSH and 20 mg multiwall carbonnanotubes were used.The effect of critical parameters such as initial pH of thesolution (3-9), sample flowrate (0.5-2 ml min -1 ), elutionsolvent flowrate (0.5-2 ml min -1 ), elutionsolvent concentration(0.005 to 0.5 M),and elutionsolvent volume(2-10 ml) on the metals ions recoveries percentage were investigated. In this study, these factors were optimized through one-at-a-timemethod. The optimum conditions were achievedin preconcentration of Pb(II), 50 ml Pb(II) solution passed through the column including 110 mg modified carbon nanotubes as an adsorbent. The optimum conditions for Pb(II) obtained were: pH6.0, sample flowrate of 1.5 ml min -1 , elution solvent flowrate of 1.5 ml min -1 , elutionsolvent concentrations of 0.05 M, elutionsolvent volume of 2ml. For preconcentrationof Pb(II).Pb(II) ions wereeluted with nitric acid (as an elution solution) and the amount of them was measured using atomic absorption spectrometry. Under theoptimum condition, Pb(II) io preconcentrated 500-fold in aqueous sample. Therefore, preconcentration factor of soo was obtained with a detection limit of 2.4ngml -1 .Maximum adsorption capacity of 500 µg g -1 for Pb(II) under the optimum conditions and 25±2 o C were obtained.Relative standard deviations of six experiments werecalculated as 3.4% for 0.5 µgml -1 Pb(II) ions in aqueous solutions. To evaluate the applicability of this method,lead(II) in wastewater and tap water samples was measured.The same SPE system was used for Cd(II)preconcentration. In the same conditions with Cd(II).The effect of critical parameters such as initial pH of the solution (3-9), sample flowrate (0.5-2 ml min -1 ), elutionsolvent flowrate (0.5-2 ml min -1 ), elutionsolvent concentration (0.01 to 0.5 M), and elutionsolvent volume (2-10 ml) on the metals ions recoveries percentage were investigated.For optimization of Cd(II), one-at-a-timemethod is used. For obtaining optimization condition in preconcentration of Cd(II), 50 ml Cd(II) solution passed from column including 110 mg modified carbon nanotubes with Cyanuric-SH and carbon. This work done in some levels of parameters.The optimum condition for Cd(II) were: pH=7.0, sample flowrate of 1ml min -1 , elution solvent flowrate of 1.5 ml min -1 , Keywords Preconcentration, CyanuricSH, Multiwalledcarbonnanotubes, Cadmium(II), Lead(II), Preconcentration factor, Detection limit