Utilisation of solid phase extraction procedures for preconcentration and determination of vanadium and chromium in various types of water samples by atomic absorption spectrometry

Abstract

In the present work, sensitive and simple methods for determination of vanadium (V) by electrothermal atomic absorption spectrometry (ETAAS) and for determination of chromium (VI) by flame atomic absorption spectrometry (FAAS) after selective preconcentration by solid phase extraction (SPE) on a Chromabond® NH₂ column have been developed. The first procedure for the preconcentration of vanadium (V) is based on the adsorption of vanadium (V) as chelate with Alizarin Red S on the sorbent at pH 5.5. The second procedure was utilised for preconcentration of chromium (VI) and also for speciation of chromium (III) and chromium (VI) using the same column at pH 5.5 without chelating agent. The influence of various experimental variables affecting the recovery of SPE procedure, i.e. pH of the sample solution, concentration of chelating agent as well as volume and concentration of elution solution, were investigated. Under the optimised experimental conditions, the detection limits (calculated as three times the standard deviation (SD) of the blank signal, divided by the slope of the calibration graph) for vanadium (V) and chromium (VI) were 0.11 and 11.7 µg L⁻¹, respectively. The developed methods were applied successfully to the determination of vanadium (V) and chromium (VI) in different water samples.

Keywords:

• vanadium
• chromium
• solid phase extraction
• preconcentration
• water samples
• ETAAS
• FAAS

Acknowledgements

Financial support from the Scientific Grant Agency of the Ministry of Education of the Slovak Republic VEGA/1/0430/08, the Grant UK/324/2008 and Centrum of Excelence AP VVCE–0070–07 is highly acknowledged.