title: Trace vanadium analysis by catalytic adsorptive stripping voltammetry using mercury-coated micro-wire and polystyrene-coated bismuth film electrodes.
abstract: An electrochemical technique has been developed for ultra-trace (ng L(-1)) vanadium (V) measurement. Catalytic adsorptive stripping voltammetry for V analysis was developed at mercury-coated gold micro-wire electrodes (MWEs, 100 microm) in the presence of gallic acid (GA) and bromate ion. A potential of -0.275 V (vs Ag/AgCl) was used to accumulate the complex in acetate buffer (pH 5.0) at the electrode surface followed by a differential pulse voltammetric scan. Parameters affecting the electrochemical response, including pH, concentration of GA and bromate, deposition potential and time have been optimized. Linear response was obtained in the 0-1000 ng L(-1) range (2 min deposition), with a detection limit of 0.88 ng L(-1). The method was validated by comparison of results for an unknown solution of V by atomic absorption measurement. The protocol was evaluated in a real sample by measuring the amount of V in river water samples. Thick bismuth film electrodes with protective polystyrene films have also been made and evaluated as a mercury free alternative. However, ng L(-1) level detection was only attainable with extended (10 min) deposition times. The proposed use of MWEs for the detection of V is sensitive enough for future use to test V concentration in biological fluids treated by the advanced oxidation process (AOP).
authors.affiliation: Department of Chemistry, The University of Tennessee, Knoxville, TN 37996-1600, USA.
authors.forename: Royce
authors.initials: R
authors.lastname: Dansby-Sparks
authors.forename: James Q
authors.initials: JQ
authors.lastname: Chambers
authors.forename: Zi-Ling
authors.initials: ZL
authors.lastname: Xue
mesh_terms: D000327:Adsorption; D001729:Bismuth / Q000737:chemistry*; D001959:Bromates / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D005707:Gallic Acid / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D008628:Mercury / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014639:Vanadium / Q000032:analysis*
chemical_list: D001959:Bromates; D008567:Membranes, Artificial; D011137:Polystyrenes; D014639:Vanadium; D005707:Gallic Acid; D006046:Gold; D008628:Mercury; D001729:Bismuth