Simultaneous preconcentration of vanadium(V/IV) species with palmitoyl quinolin-8-ol bonded to amberlite XAD 2 and their separate spectrophotometric determination with 4-(2-pyridylazo)-resorcinol using CDTA as masking agent

Abstract

This paper reports the simultaneous preconcentration and separation of trace amounts of V species in synthetic solutions and seawater with palmitoyl quinolin-8-ol bonded amberlite XAD 2 copolymer resin column prior to simultaneous speciation analysis. Both V(IV) and V(V) species could be sorbed and preconcentrated by the resin. Both vanadium species were quantitatively eluted together from the resin column using HCl as stripping agent and used for speciation studies. For the speciation analysis of eluted V species, the selected route involved spectrophotometric determination of total vanadium with 4-(2-pyridylazo)-resorcinol (PAR) and vanadate estimation by masking vanadyl with 1,2 cyclohexanediaminetetraacetic acid (CDTA). The preconcentrated V species were assayed spectrophotometrically with PAR at 542 nm, and the results were compared with those of FAAS. The detection limits of V(V) with spectrophotometry and FAAS were 1.6 and 0.9 μg l −1, respectively. The optimal experimental parameters such as pH, sample flow rate, desorption flow rate, redox behaviour of V(IV) and V(V) in resin and volume of eluent and sample were investigated. The values obtained for the preconcentration factor by the two methods were nearly consistent, and were in the range 150-fold. Analysis of certified reference material (IAEA-405) by the proposed method showed good agreement with the certified value. The established procedure was employed for preconcentrating the vanadium species from artificial and real seawater.