APPLICATION OF MULTI-WALLED CARBON NANOTUBES AS SUBSTRATE FOR THE ON-LINE PRECONCENTRATION, SPECIATION AND DETERMINATION OF VANADIUM BY ETAAS

RAÚL A. GIL, SILVIA N. GOYANES, GRISELDA POLLA, PATRICIA SMICHOWSKI, ROBERTO A. OLSINA, LUIS D. MARTINEZ

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY

Royal Society of Chemistry

Año: 2007 vol. 22 p. 1 - 6

0267-9477

This paper presents the development of a pre-concentration and speciation method for inorganicvanadium species by flow injection solid phase extraction-electrothermal atomic absorptionspectrometry (FI-SPE-ETAAS). This was carried out by employing a conical mini-column filledwith multi-walled carbon nanotubes mounted in the arm of the autosampler of the ETAAS. Thissystem was applied to the on-line pre-concentration and speciation of vanadium in natural watersin conjunction with ETAAS determination. The time required for the pre-concentration of 1.0 mlof sample (1.0 ml min1), elution/injection (0.2 ml min1), reading/data acquiring andconditioning was about 2.9 min, resulting in a sample throughput of 20 samples per hour. A20-fold total enrichment factor for a sample volume of 1.0 ml was obtained with respect to thevanadium determination by ETAAS without pre-concentration. The relative standard deviationfor six replicates containing 200 ng l1 was 3.3%. A limit of detection (3s) of 19 ng l1 wasachieved and the limit of quantification was estimated (10s), obtaining a characteristicconcentration of 63 ng l1. The calibration curve was linear from the quantification limit up to1500 ng l1, with a correlation coefficient of 0.9996. This method permitted us to determine thetotal inorganic vanadium in natural waters. For speciation purposes, V(IV) was masked with 1,2cyclohexanediaminetetraacetic acid (CDTA) in order to determine the V(V) concentrationselectively.