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Solid Phase Extraction Of Copper(II) From Water Samples On Silica Gel Using 4-Ethyl-1-(Pyridin-2-yl) Thiosemicarbazide

A.A.El-Asmy, M.M.Hassanian, M.H.Abdel-Rhman

Rapid and selective procedure for extraction, preconcentration and spectrophotometric determination of Cu(II) at trace level using EPTS was investigated. Cu2(EPTS)3/2(H2O)2.Cl2.½EtOH was the formula of the complex isolated in the solid state. In EtOH-H2O solution(50%), the ratio of M:L (1:1) is formed with maximum absorption at 675nm(ε=2.9x103 cm-1M-1). The stability constant of the formed complex was evaluated spectrophotometrically and pH-metrically. The complex was easily immobilized by adsorption on silica gel and eluted with 5 M HNO3. The extraction parameters(pH, amount of EPTS, sample volume and detection limit) were evaluated in synthetic, spiked natural and tape water samples. The interfering effect of some cations and anions on the recovery of Cu(II) was studied. At optimum conditions, the recovery of Cu(II) was 97±1% at 95% confidence level. The adsorption isotherm was studied and the binding equilibrium constant and the adsorption capacity were 3.585 lmg-1 and 520.8 μg g-1, respectively. The detection limit and relative standard deviation were 10 μg g-1 and 1.5%, respectively. The proposed method is applied for the separation and preconcentration of Cu(II) in natural water samples.