The selection of a chemical modifier for vanadium determination in various types of natural waters by electrothermal atomic absorption spectrometry

Abstract

Various modifiers (ascorbic acid, NH₄NO₃, EDTA, NH₄SCN and a mixture of Pd/Mg(NO₃)₂) are compared for the accurate determination of vanadium in natural waters by electrothermal atomic absorption spectrometry. The interferences of compounds commonly present in natural waters, such as NaCl, CaCl₂, MgCl₂ and FeCl₃ are studied. Matrix interferences were effectively eliminated by ascorbic acid or ammonium nitrate. For comparison, the standard addition method was applied without a modifier which provided satisfactory results. The accuracy of the method was confirmed by analysis of certified reference materials of waters (‘Trace Metals in Drinking Water’ and SRM 1643e ‘Trace Elements in Water’) as well as by recoveries of vanadium spiked to tap water, mineral water, synthetic riverine and synthetic sea waters. The limits of detection and characteristic masses for ascorbic acid and ammonium nitrate as the modifiers were 1.71 and 1.56 µg L⁻¹ and 70 and 67 pg, respectively. Recovery was in the range of 98–105% and RSD was less than 5%.

Keywords:

• vanadium
• ETAAS
• chemical modifiers
• natural waters

Acknowledgements

The authors wish to acknowledge the financial support received from the Scientific Grant Agency of the Ministry of Education of the Slovak Republic No. VEGA/1/0430/08 and Grant of Slovak Research and Development Agency No. VVCE–0070–07.