Online Preconcentration of Sb(lll) using Si02/ AI20 3/Sn02 Ternary Oxide Coupled with HGAAS

The oxide ternary was previously synthesized and characterized as phase extractor for online preconcentration of Pb2+ by FAAS.1 ln this work, studies are been performed with the aim to develop an analytical method using a ternary oxide coupled to Hydride Generation Atomic Absorption Spectrometry (HG AAS) for antimony determination. Chosen conditions for pH study of Sb3+ were: HCI 1.5 mol L-1 , NaBH4 3.0% (m/v) in NaOH 0.5% (m/v) and 20.0 μg L-1 of Sb(lll). Online FIA-HG AAS system parameters were: 0.8, 2.5 e 6.20 ml min-1 for borohydride, hydrochloric acid and preconcentration flow rate, respectively. The material (50.0mg) was packed into a column and coupled online to commutator injector. Sample was aspirated and after 3.15 minutes the injector was shifted to injection position and antimony retained was eluted by the HCI towards the hydride generation. Then, Sb(lll) is easily reduced to stibine (SbH3) with borohydride at acid medium. From the results obtained higher intensity was observed at pH 3.5. Above that, a slight decrease was realized and the intensity remains up to pH 7.5. Therefore, no influence from Sb(lll) preconcentration was detected from pH 2.5 to 7.5. ln the pH range of 2.0 - 11.0, Sb(lll) should form a neutral complex Sb(OH)3.2 The surface offers oxygen for hydrogen bonds with Sb(OHh, but the excess of OH- competes with the surface, which explain the low preconcentration at higher pH value (pH 9.0).3