Analytical chemistry 2001-09-15

Nonaqueous catalytic fluorometric trace determination of vanadium based on the pyronine B-hydrogen peroxide reaction and flow injection after cloud point extraction.

E K Paleologos, M A Koupparis, M I Karayannis, P G Veltsistas

Index: Anal. Chem. 73(18) , 4428-33, (2001)

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Abstract

The catalytic effect of vanadium on the pyronine B-H2O2 system is examined. Enhancement of the catalytic reaction rate along with the efficiency and selectivity against vanadium is achieved in a formic acid environment in the presence of a nonionic surfactant (Triton X-114). Elimination of drastic interference caused by inorganic acids and aqueous matrix along with a 50-fold preconcentration of vanadium are facilitated through cloud point extraction of its neutral complex with 8-quinolinol in an acidic solution. Subsequent flow injection analysis (FIA) with fluorometric detection renders the proposed method ideal for selective and cost-effective determination of as little as 0.020 microng L(-1) vanadium in environmental, biological, and food substrates. The preconcentration step can be applied simultaneously to multiple samples, allowing for massive preparation prior to analysis, compensating, thus, for the time-consuming procedure.