Simultaneous speciation of inorganic arsenic and antimony in natural waters by dimercaptosuccinic acid modified mesoporous titanium dioxide micro-column on-line separation and inductively coupled plasma optical emission spectrometry determination

A novel absorbent was prepared by dimercaptosuccinic acid chemically modifying mesoporous titanium dioxide and was employed as the micro-column packing material for simultaneous separation/preconcentration of inorganic arsenic and antimony species. It was found that both trivalent and pentavalent of inorganic As and Sb species could be adsorbed quantitatively on dimercaptosuccinic acid modified TiO2 within a pH range of 4-7, and only As(III) and Sb(III) could be quantitatively retained on the micro-column within a pH range of 10- 11 while As(V) and Sb(V) were passed through the micro-column without the retention. Based on this fact, a new method of flow injection on-line microcolumn separation/preconcentration coupled to inductively coupled plasma optical emission spectrometry was developed for simultaneous speciation of trace inorganic arsenic and antimony in natural waters. Under the optimized conditions, an enrichment factor of 10 and sampling frequency of 10 h(-1) were obtained with on-line mode. The detection limits of As(III), As(V), Sb(III), and Sb(V) are 0.53, 0.49, 0.77 and 0.71 ng mL(-1) for on-line mode and as low as 0.11, 0.10, 0.15 and 0.13 ng mL(-1) for off-line mode due to its higher enrichment factor (50), respectively. The relative standard deviations of two modes are less than 6.7% (C 20 ng mL(-1), n=7). The concentration ratio of lower oxidation states/higher oxidation states changing from 1:10 to 10:1 has no obvious effect on the recoveries of As(III) and Sb(III). In order to validate the developed method, two certified reference materials of GSBZ5004-88 and GBW(E)080545 water sample were analyzed and the determined values are in good agreement with the certified values. The proposed method was successfully applied to the simultaneous speciation of inorganic arsenic and antimony in natural waters. (C) 2007 Elsevier B.V. All rights reserved.