title: Arsenic speciation in water and snow samples by adsorption onto PHEMA in a micro-pipette-tip and GFAAS detection applying large-volume injection.
abstract: 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 micro-pipette-tip. The adsorbed arsenic was quantitatively eluted by 700 μL 0.25 M NH(3) and determined by graphite furnace atomic absorption spectrometry (GFAAS). Injection of larger volume (i.e., 50 μL v.s. conventional 10-20 μL) eluent into graphite furnace and the use of Mg(NO(3))(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 μg 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 (3s) 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 μg 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 μg L(-1) As(III) and As(V), the recoveries varied between 96 and 100%.
authors.affiliation: Çankiri Karatekin University, Faculty of Science, Department of Chemistry, 18100 Çankiri, Turkey. serhatdoker@gmail.com
authors.forename: Serhat
authors.initials: S
authors.lastname: Döker
authors.forename: Lokman
authors.initials: L
authors.lastname: Uzun
authors.forename: Adil
authors.initials: A
authors.lastname: Denizli
mesh_terms: D001151:Arsenic / Q000032:analysis*; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry; D012016:Reference Values; D012914:Snow / Q000737:chemistry*; D052616:Solid Phase Extraction; D013054:Spectrophotometry, Atomic; D013859:Thiocarbamates / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D011759:Pyrrolidines; D013859:Thiocarbamates; D014867:Water; D011102:Polyhydroxyethyl Methacrylate; C020972:pyrrolidine dithiocarbamic acid; D006108:Graphite; D001151:Arsenic