INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Determination of As(III) in non acidified groundwater samples for inorganic speciation analysis using flow injection hydride generation atomic absorption spectrometry
MIRNA SIGRIST; HORACIO BELDOMENICO; MABEL TUDINO
Taylor and Francis
Año: 2010 vol. 43 p. 458 - 458
A flow injection system coupled to hydride generation atomic absorption spectrometry with heated quartz tube atomizer was employed for the selective determination of As(III) in real groundwater samples under non acidic conditions. Even though low pH values seem to be an unavoidable requisite for hydride generation, the use of low acidity conditions was carefully evaluated in order to minimize the interconversion of the redox arsenic species. The As(III) hydride was generated using 0.1 mol L-1 HCl as carrier solution and 0.2% (m/v) NaBH4 (THB) in 0.025% NaOH as the reductant. A coil reaction larger than the used one for higher acidity conditions (480 mm instead of 115 mm) was selected. The generated hydride was transported to the atomizer by a nitrogen flow of 75 ml min-1. The main parameters that influenced the signal intensity and shape were studied. Under optimized conditions, a detection limit (3ó) of 1.0 µg L-1 As(III) was obtained for a 500 µl sample volume. The analytical recovery ranged between 90-98%. In addition, the total inorganic arsenic concentration in the samples was determined on sample aliquots acidified with concentrated HCl and pre-reduced with 5% KI - 5% C6H8O6 solution. HCl 1.2 mol L-1 as carrier solution, NaBH4 0.2% (m/v) as reductant and a nitrogen flow rate of 75 ml min-1 were used in this case. The concentration of As(V) was calculated by difference between the total inorganic arsenic and As(III) concentrations.