Speciation of silver nanoparticles and Ag(I) species using cloud point extraction followed by electrothermal atomic absorption spectrometry

Silver nanoparticles in the presence of Triton-X114 were extracted into a micellar phase obtained after incubation at 40 degrees C for 10 min followed by centrifugation. After injection of an aliquot (30 mu L) of the surfactant-rich phase into the electrothermal atomizer, the enrichment effect due to cloud point extraction allowed a detection limit of 2 ng L-1 silver to be achieved. The preconcentration factor was 242, and the repeatability for ten measurements at a 50 ng L-1 silver level was 4.6%. Ag(I) species were adsorbed onto the silver nanoparticles and were also extracted in the micellar phase. The incorporation of 0.01 mol L-1 ammonium thiocyanate to the sample solution prevented the extraction of Ag(I) species. Speciation was carried out using two extractions, one in the absence and the other in the presence of thiocyanate, the concentration of Ag(I) species being obtained by difference. The procedure was applied to the determination of silver nanoparticles and Ag(I) species in waters and in lixiviates obtained from sticking plasters and cleaning cloths. (C) 2014 Elsevier B.V. All rights reserved.