Field-based application of developed solid phase extraction with inductively coupled plasma mass spectrometry for vanadium speciation analysis of groundwaters from Argentina

Abstract

High levels of vanadium have been reported in groundwater (<0.05–5300μgL−1 V) from different parts of Argentina, yet no detailed study of vanadium speciation has been performed. A highly selective strong anion exchange – solid phase extraction (SAX-SPE) method was used (in-situ) for vanadium speciation analysis of groundwater samples from La Pampa - LP (General San Martin and Eduardo Castex) and Buenos Aires - BA (San German) provinces in Argentina. In this method both vanadyl (VIV) and vanadate (VV) were trapped by the complexation with disodium ethylenediaminetetraacetic acid on a pre-conditioned SAX cartridge. In the laboratory, vanadium species were separated at different eluent pH levels. VIV was eluted at pH 4 using methanol and tetrabutylammonium hydroxide. VV was eluted at pH 8 using dihydrogen ammonium phosphate. The eluted species were analysed by inductively coupled plasma mass spectrometry (ICP-MS). This method was validated using an inter-analytical method comparison with HPLC-ICP-MS. A Paired t-test revealed that there was no significant difference (probability, P<0.05) between the two methods. VV was found to be predominate species in both sample collection areas (LP: 69 – 100%, BA: ‎33 – 89% of species) over the range of 158.0 – 4748.0μgL−1 in LP and 88.5 – 504.0μgL−1 in BA. VIV was found at higher levels (29.0−301.0μgL−1) in Buenos Aires compared to General San Martin groundwater (4.4 – 161.0μgL−1). The results enhance the potential knowledge of the speciation of vanadium in terms of water quality and human health.