A new chemically modified silica gel with benzothiazo ethylacetate (Si-Benzo) has been synthesized. This sorbent was characterized by ATR-spectrometry, solid state NMR spectrometry and elemental analysis. The metal sorption properties of Si-Benzo were studied towards PB2+, CU2+, Ni2+, Co2+ and Cd2+. The determination of metal ions was carried out on FAAS. For batch method, the optimum pH ranges for metals extraction were 4-6. The contact times to reach the equilibrium were less than 10 minutes. The adsorption isotherm fitted the Langmuir’s model showed the maximum sorption capacities of 0.22, 0.14, 0.013, 0.007 and 0.005 mmol/g for Pb2+, Cu2+, Co2+, Cd2+ and Ni2+ respectively. In the column system, a mini-column packed Si-Benzo at 20-70 mg for metal ions was studied at a flow rate of 2.5 mL/min. The sorbed metals were eluted by 1% HNO3 at a flow rate of 0.5 mL/min. No interference from Na+, K+, Mg2+, Ca2+, Cl- and SO42- at 10, 100 and 1000 mg/L was observed. The preconcentration factor obtained was 20 for Pb2+ and Cu2+. The preconcentration procedure was applied to the analysis of natural water samples. The accuracy was evaluated by spiked method. The results showed that the preconcentration of Pb2+ and Cu2+ for pond water, tap water and drinking water from chulalongkorn university under the optimum conditions gave high accuracy and precision (%RSD <= 7).