Selective determination of V(IV) and V(V) in seawater by solid phase extraction and electrothermal atomic absorption spectrometry

Abstract

A selective and sensitive method was developed for the separation and preconcentration of V(IV) and V(V) from seawater samples using a Chelex®-100 column. The influence of different parameters in the separation procedure such as pH of the sample, volume and concentration of extracting agents [NH 3 for V(V) and HNO3 for V(IV)], sample load flow rate and the eluting flow rate were studied. The separated species were then determined by electrothermal atomic absorption spectrometry (ETAAS). The limits of detection (LODs) and limits of quantification (LOQs) obtained using 50 mL of a seawater sample were 0.15 and 0.50 μgL-1, respectively, for V(IV) and 0.10 and 0.33 μgL-1, respectively, for V(V). The recovery percentages were 95.3 ± 3% and 92.3 ± 3% for V(IV) and V(V), respectively. The method was applied to the V(IV) and V(V) determination in seawater samples from the Galician coast. The only species detected in the three samples studied was V(V), which is the most toxic form and was found in concentration levels ranging from 0.1 to 0.25 μg L-1. The method is simple, quick, and low cost.