Determination of Vanadium in Food Samples by Cloud Point Extraction and Graphite Furnace Atomic Absorption Spectroscopy

A preconcentration methodology utilizing the cloud point phenomenon is described for the determination of total vanadium by graphite furnace atomic absorption spectrometry. Cloud point extraction method was based on the formation of a ternary complex between vanadium, 2-(2A '-thiazolylazo)-p-cresol, and ascorbic acid, with subsequent extraction-preconcentration of the formed complexes using Triton X-100. Optimization of different parameters was evaluated. Under optimal conditions, a calibration curve was constructed, showing a linear range of 1.0-60 ng mL(-1) and the limit of detection and relative standard deviation for preconcentration of a 10-mL sample were found to be 0.05 ng mL(-1) and 3.9%, respectively. The preconcentration factor was found to be tenfold for 10 mL of water sample. The technique has been applied succesfully to the determination of vanadium traces in wine, tea, and tomato samples and the recoveries of added vanadium were in the range 96-102%.