Speciation and preconcentration of inorganic antimony and manganese in waters using microcolumn-flow injection system and determination by atomic absorption spectrometry

Abstract

A selective separation/preconcentration method utilizing microcolumn of a chelating resin with -SH functional groups (Duolite GT-73) was proposed for the determination of Sb(III) in waters by segmented flow injection HGAAS. The selectivity of the resin towards Sb(III) and Sb(V) was not dependent on the pH of the solution; Sb(III) was retained by the resin quantitatively in a broad pH and acidity range whereas Sb(V) was not retained at all and could be determined after a pre-reduction step with L-cysteine.Spike recoveries were tested at various concentration levels in different water types and were found to vary between 80-110 %. Accuracy of the proposed methodology was checked by analyzing a standard reference material and a good correlation was found between the determined and the certified values. The method was applied to several bottled drinking water samples for antimony determination. The samples were found to contain no antimony above the permissible level (5 ug/L). The applicability of the microcolumn separation/preconcentration method for flow injection systems was also demonstrated.A similar separation system was proposed for Mn determination in waters. A macroporous resin with no functional groups (Amberlite XAD-7HP) was employed for the speciation of Mn(II) and Mn(VII) and was found to retain Mn(VII) at pH values from 4.0 to 12.0. Mn(II) was retained at a pH of 12.0, possibly due to MnO2 precipitation rather than adsorption by the resin.