Selective solid-phase extraction of trace Au(III), Pd(II) and Pt(IV) using activated carbon modified with 2,6-diaminopyridine

A new sorbent was prepared by immobilization of 2,6-diaminopyridine on activated carbon and then used as a solid-phase extractant for trace Au(III), Pd(II) and Pt(IV) before their determination by ICP-AES. Effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the potentially interfering ions were investigated. The optimum pH value is 1. The maximum static adsorption capacity for the three ions is 202.7, 38.5 and 30.1 mg g −1 , respectively. The adsorbed metal ions can be completely eluted by 2 mL of the eluent solution that contains 0.05 mol L −1 HCl and 5% thiourea. Common other ions do not interfere. The detection limits (3σ) are 0.16, 0.33 and 0.29 ng mL −1 , respectively. The relative standard deviation (RSD) was lower than 3.0% ( n = 8). The new sorbent was applied to the preconcentration of the three ions in ore and rock samples with satisfactory results. Figure Au(III), Pd(II), Pt(IV) are absorbed at pH 1. The maximum static adsorption capacity is 202.7, 38.5 and 30.1 mg g −1 . The eluent is 2 mL of the eluent solution that contains 0.05 mol L −1 HCl and 5% thiourea. The relative standard deviation (RSD) was lower than 3.0% ( n = 8).