Article

Determinación simultánea de Cr, Ni y V en orina mediante et aas

Química Nova (Impact Factor: 0.66). 01/2011; 34(6):940-944. DOI: 10.1590/S0100-40422011000600005

ABSTRACT

A procedure for the simultaneous determination of Cr, Ni, and V in urine by electrothermal atomic absorption spectrometry (ET AAS) was optimized by factorial design, and performed at a pyrolysis and atomization temperatures of 1300 and 2500 ºC, respectively, using 15 µg de Mg(NO3)2 as chemical modifier. Characteristics mass of 14, 6 and 220 ρg and detection limits of the method of 0.07, 0.38 and 0.75 µg L-1 were obtained for Cr, Ni and V respectively. The methodology was validated using a Liphochek Urine Metals Control sample (Bio-Rad) (P=0.05). The methodology was applied to samples of voluntary Venezuelan people, not environmentally exposed to specific emissions, and results ranging from < LOD-1.1 and 1.3-3.3 µg L-1 was observed for Cr and V, respectively, and not detectable levels for Ni.

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    ABSTRACT: This study describes the optimization and validation of a quick and simple method for the simultaneous determination of total content and available fractions of As, Cr, Cu, Ni, Pb and Tl in sediments by ET AAS, which has been proved to be useful for environmental research. The optimization was carried out using a 3(3) Box-Behnken factorial design which was applied to matrices of total digestion and to stages 1 and 2 of the modified BCR sequential extraction scheme for sediments in order to determine the appropriate atomization temperatures and masses for the chemical modifiers: Pd(NO(3))(2) and Mg(NO(3))(2). The simultaneous determination of the elements in all matrices considered was performed, without the use of chemical modifiers at atomization temperatures of 1700 °C for Cd and Tl, and 2100 °C for As, Cu, Cr, Ni and Pb, using a standard calibration curve for calibration purposes. The characteristic masses and limits of detection obtained were 36.5, 1.8, 6.5, 28, 34, 46.5 and 48 ρg and 0.11, 0.001, 0.022, 0.04, 0.2, 0.03 and 0.003 μg g(-1) for As, Cd, Cr, Cu, Ni, Pb and Tl, respectively. The analytical procedure was validated by analyzing three sediment certified reference materials (CRM NCS DC 73315 and LKSD-4 for total content and BCR 701 for available fractions). Good accuracy was obtained (tested statistically, P=0.05, and shown by the high recovery for each element in each matrix), except for total As in the matrix of total digestion, where losses of the analyte could be attributed to sample treatment with HNO(3). The precision of the procedure was between 0.6% and 6%.
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