Solid phase extraction and spectrophotometric determination of vanadium

2590-2594A sensitive, selective and rapid method has been developed for the determination μg/L level of vanadium based on the rapid reaction of V(V) with 2-(2-quinolylazo)-5-dimethylaminophenol (QADMAP) and the solid phase extraction of the colored chelate with C18 cartridge. QADMAP reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH=3.5) and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1:2 (V:QADMAP). This chelate is enriched by solid phase extraction with C18 cartridge and the enrichment factor of 50 was obtained by elution of the chelate from the cartridge with ethanol. Molar absorptivity of the chelate has been found to be 1.22×105 L.mol-1.cm-1 at 585 nm. Beer's law is obeyed in the range of 0.01-0.6 μg/mL. The detection limit is 0.04 μg/L in original samples. This method has also been applied to the determination of V(V) in water and biological samples. The relative standard deviations are 1.8-2.5%, and the recoveries are 96-103%