Study on solid phase extraction and spectrophotometric determination of vanadium with 2-(2-quinolylazo)-5-diethylaminophenol

A sensitive, selective and rapid method has been developed for the determination μg/L level of vanadium ion based on the rapid reaction of vanadium(V) with 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) and the solid phase extraction of the colored chelate with C 1 8 cartridge. The QADEAP 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(V) to QADEAP). This chelate was enriched by solid phase extraction with C 1 8 cartridge and the enrichment factor of 50 was obtained by elution of the chelates from the cartridge with ethanol. The molar absorptivity of the chelate is 1.28 x 10 5 L mol - 1 cm - 1 at 590 nm in the measured solution. Beer's law is obeyed in the range of 0.01-0.6 μg/mL. The detection limit is 0.04 μg/L in the original samples. This method was applied to the determination of vanadium(V) in water and biological samples with good results.