Arsenic speciation in water and snow samples by adsorption onto PHEMA in a micro-pipette-tip and GFAAS detection applying large-volume injection


TALANTA, cilt.103, ss.123-129, 2013 (SCI İndekslerine Giren Dergi) identifier identifier identifier


A miniaturized solid phase extraction procedure has been developed for ultra-trace determination of inorganic arsenic species. Arsenic(III) as pyrrolidinedithiocarbamate complex was selectively adsorbed on 30 mg poly(hydroxyethyl methacrylate) (PHEMA) micro beads, which is simply packed into a micropipette-tip. The adsorbed arsenic was quantitatively eluted by 700 mu L 0.25 M NH3 and determined by graphite furnace atomic absorption spectrometry (GFAAS). Injection of larger volume (i.e., 50 mu L v.s. conventional 10-20 mu L) eluent into graphite furnace and the use of Mg(NO3)(2) as chemical modifier have improved atomic absorption signal intensity (sensitivity as characteristic mass of 25 pg) and precision (RSD of 2.6%, c=10 mu g L-1, n=11). Total arsenic amount was determined after reduction of arsenic(V) to arsenic(III) by thiourea-HCl system. As(V) concentration was calculated by the difference between As(III) and total arsenic. The detection limit (3 s) of the method was found as 10 ng L-1 As(III) with an enrichment factor of 86. The relative standard deviation and relative error for six replicate determinations of 0.5 mu g L-1 As(III) were found to be 4.0% and -0.7%, respectively. The method was successfully applied to drinking water, snow and reference water (SEM-2011) samples. When the samples were spiked with 0.5 and 1.0 mu g L-1 As(III) and As(V), the recoveries varied between 96 and 100%. (C) 2012 Elsevier B.V. All rights reserved.