INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
FI-SPE-ETAAS determination of Cr(VI) by selective separation and preconcentration on a lab-made hybrid mesoporous solid microcolumn
Autor/es:
MANUELA KIM, JORGE STRIPEIKIS, MABEL TUDINO.
Lugar:
Salvador, Bahía, Brasil
Reunión:
Simposio; 10th Rio Symposium on Atomic Spectrometry; 2008
Resumen:
We present the on-line determination of
ultratrace levels of Cr(VI) in natural waters by means of a solid phase flow
injection system coupled to an electrothermal atomizer (FI-SPE-ETAAS). A lab-made hybrid mesoporous material was prepared with silica functionalized with
3-aminopropyltriethoxy sylane (APS) by sol-gel methodology and one-pot synthesis and characterized by
IR, DRX and SEM. Then, the solid was employed as filling of the microcolumn (bed
volume: 7.9 µL) held in the flow through system for selective separation and
preconcentration of Cr(VI). The maximum capacity of adsorption (4.35 mmol g-1) was
observed for pH values between 2-3, whilst Cr (III) was found to remain in
solution (adsorption capacity= 0.007 mmol g-1). Since the analyte was
strongly retained by the filling in the anionic form, hydroxilamonium chloride
1.0.10-4 molL-1 in hydrochloric acid 1 mol L-1
was selected as eluent due to its redox characteristics. In this way, the
sorbed Cr(VI) was easily released in the cationic form. The enrichment factor
(EF) was found as a compromise between sensitivity and sample throughput and a
value of 20 was obtained under optimized conditions: pH 2, sample loading 2 mL
min-1, elution flow rate 1 ml min-1.
Analytical performance will be presented in terms of limit
of detection, linear range, RSD%, sample throughput, microcolumn lifetime,
easiness of operation, etc.
The applications to
the determination of Cr(VI) in natural waters will be shown as well as the
validation of the analytical results.