Solid Phase Extraction and Preconcentration of Trace Gallium, Indium, and Thallium Using New Modified Amino Silica

Amino silica gel functionalized with 2-hydroxy-5 -(2-hydroxybenzylideneamino)benzoic acid was synthesized, characterized and used as adsorbent for the removal of Ga 3+ , In 3+ and Tl 3+ from aqueous solution prior to their determination by flame atomic absorption spectrometry. Experimental parameters that affect the separation process were investigated in both batch and column modes. The maximum adsorption capacities of the sorbent are 61.7 mg g −1 , 81.3 mg g −1 and 133.0 mg g −1 for Ga 3+ , In 3+ and Tl 3+ , respectively. The preconcentration factor is 200 and the limits of detection of Ga 3+ , In 3+ and Tl 3+ are 4.10 μg L −1 , 1.55 μg L −1 and 1.21 μg L −1 , respectively. Interference by Al 3+ can be masked by the addition of F − ; and that of Fe 3+ by its reduction to Fe 2+ using 10% ascorbic acid. The method was successfully applied for the determination of these ions in water, sediments and liquid crystal display samples.