Determination of trace levels of dissolved vanadium in seawater by use of synthetic complexing agents and inductively coupled plasma–atomic emission spectroscopy (ICP–AES)

Abstract.

In the determination of traces of dissolved vanadium in complex matrices such as seawater, separation and enrichment from the matrix is of special importance. A wide variety of methods has been proposed for preconcentration, depending to the nature of samples and the methods to be used for measurement. Among these methods separation techniques based on sorption on to chelating resins seem convenient, rapid, and capable of achieving a high concentration factor. The methods proposed in this paper are based on the transformation of all dissolved vanadium species in seawater into organic complexes by use of synthetic complexing agents such as dithizone, luminol, or 8-hydroxyquinoline; the resulting vanadium–organic complexes were sorbed on to a C₁₈ column at a flow rate of 5 mL min^–1. The vanadium sorbed on the C₁₈ columns was then stripped by use of nitric acid (2 mol L^–1) and analysed by inductively coupled plasma–atomic emission spectroscopy, ICP–AES. This method was optimised and use of other chelating resins, such as chelamine, chelex-100, and immobilised 8-hydroxyquinoline and was compared by passing seawater samples directly over the resins. The experimental conditions (pH, acid used for elution, and contact time between the liquid sample and the resin) were optimised. The results were compared for all the resins used and were indicative of excellent and coherent reproducibility.