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

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 (V(IV)) and vanadate (V(V)) 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. V(IV) was eluted at pH 4 using methanol and tetrabutylammonium hydroxide. V(V) 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. V(V) 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. V(IV) 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.