Determination of trace thallium by flow injection combined with graphite furnace atomic absorption spectrometer based on immobilized p-dimethylaminobenzylidenerhodanine separation and preconcentration

The novelty of immobilized p-dimethylaminobenzylidenerhodanine is successfully prepared by using TiO2-based nanoparticles as the carrier. It is applied to preconcentrate and separate trace thallium and detect by flow injection combined with graphite furnace atomic absorption spectrometer. The results show that immobilized p-dimethylaminobenzylidenerhodanine can preconcentrate and separate trace thallium and eliminate the interference of many other ions. The optimal adsorption occurs at pH = 3.5, the retention time is 2.0 min, and the flow velocity is 2.5mL/min. The optimal desorption takes place at a flow velocity of 1.0 mL/min, 1 mL mixed solution (thiourea and HCl were both 0.1 mol/L). The recovery rate of thallium is over 95%; the amount of immobilized p-dimethylaminobenzylidenerhodanine is 22.08 mg/g; the adsorption capacity of thallium for immobilized p-dimethylaminobenzylidenerhodanine is 7.2 mg/g; the molar ratio of thallium ions and p-dimethylaminobenzylidenerhodanine is 5:2. The immobilized p-dimethylaminobenzylidenerhodanine can be recycled and reused. For the developed method, the limit of detection is 8 ng/L, the relative standard deviation is 3.7%, and the recovery is 89%–107%. The method is successfully applied to actual samples with satisfactory results.