Artigo
Dispersive liquid–liquid microextraction using ammonium O,O-diethyl dithiophosphate (DDTP) as chelating agent and graphite furnace atomic absorption spectrometry for the determination of silver in biological samples
Autor
Dittert, Ingrid M.
Vitali, Luciano
Chaves, Eduardo S.
Maranhão, Tatiane A.
Borges, Daniel L. G.
Favere, Valfredo T. de
Curtius, Adilson J.
Institución
Resumen
A new method for the determination of silver in biological samples is presented in this work. The method
involves application of dispersive liquid–liquid microextraction (DLLME) employing ammonium O,O-diethyl
dithiophosphate (DDTP) as the chelating agent for extraction and preconcentration of silver prior to
quantification using graphite furnace atomic absorption spectrometry (GFAAS). Chloroform and acetone
were selected as the extracting and dispersing solvent, respectively, at optimized volumes of 80 mL and
500 mL, respectively. The concentration of DDTP and the extraction time were optimized as 0.01% (m/v)
and 10 min, respectively. Pyrolysis (1100 C) and atomization (1800 C) temperatures were optimized
using a L'vov platform treated with 400 mg of tungsten as a permanent chemical modifier. The method
was proven virtually free from interference from major constituents of biological samples. A detection
limit of 2 ng g 1 was obtained with relative standard deviations better than 13% and an enhancement
factor of 70 was achieved. The determined concentrations for Ag in certified reference biological
samples were in good agreement with the certified values at a 95% statistical confidence limit. The
reported method using DLLME and GFAAS presented good analytical performance for Ag determination
when compared to other methods available in the literature.