Separation and preconcentration of inorganic antimony species in natural waters using phase extraction and ET AAS

Complete text of publication follows. The aim of the present work was to propose an optimal procedure for the separation and preconcentration of inorganic antimony species in natural waters prior its determination by electrothermal atomic absorption spectrometry (ET AAS). Nanometer-sized TiO2 (which has a high surface area/body weight ratio, high adsorption capacity, and strong coordination of titanium) has been used as a solid phase extractant in this study. Three different modes for the separation and preconcentration of inorganic antimony species were compared: (I) direct TiO2-slurry sampling after adsorption of antimony onto TiO2, (II) batch mode with the elution of antimony from TiO2 by a mixture of EDTA and HNO3, and (III) column system using a minicolumn packed with TiO2 with the elution by a mixture of EDTA and HNO3. Advantages and disadvantages of the three procedures were discussed and evaluated. Direct TiO2-slurry sampling offers relatively easy preparation but the high attention has to be pay to the stability of TiO2-slurry and a serious problem with the damage of a graphite tube leads to the worst reproducibility. Batch mode is the most laborious (tending to the higher risk of sample contamination) but in spite of that it offers higher reproducibility than direct TiO2-slurry sampling mode. Minicolumn system is flexible, since different initial volumes of a sample can be used (resulting in different enrichment factors and detection limits), reuse of the column is possible after regeneration and high reproducibility is achieved. Briefly, all procedures are effective for the separation and preconcentration of inorganic antimony in natural waters. Finally, the optimized procedure of direct TiO2-slurry sampling to ET AAS was used for the determination of inorganic antimony leached by drinking water from PET bottles. The work was supported by Slovak Research and Development Agency under the contracts No. LPP-0038-06, LPP-0188-06, SK-CZ-0044-07 and LPP-0146-09, by Scientific Grant Agency of Ministry of Education of Slovak Republic and the Slovak Academy of Sciences under the contracts No. VEGA 1/4463/07, VEGA 1/4464/07 and VEGA 1/0272/08 and by Ministry of Education, Youth and Sports of Czech Republic under the contract No. MEB 080813.