title: A simplified analysis of dimethylarsinic acid by wavelength dispersive X-ray fluorescence spectrometry combined with a strong cation exchange disk.
abstract: Dimethylarsinic acid (DMA(V)) was pre-concentrated from water samples using a strong cation exchange (SCX) disk functionalized with sulfonic groups, before being analyzed by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). The adsorption of DMA(V) occurred preferentially on the surface of the SCX disk, regardless of pH levels, probably due to interactions with the sulfonic functional groups. However, no other arsenic species, such as arsenate (iAs(V)), arsenite (iAs(III)), and monomethylarsonic acid (MMA(V)), were retained. The SCX-WDXRF method produced a strongly linear calibration curve (R(2)=0.9996) with its limit of detection at 0.218 μgL(-1) when a one-liter water sample was used for pre-concentration. The As intensity of the system was sensitive to the Pb content retained on the SCX disk owing to the proximity of the As-Kα and Pb-Lα lines. To compensate for this interference, a correction factor was developed by considering the calibration slope ratio between the X-ray intensity measured at a Bragg angle of 48.781° and the Pb content of the SCX disks. The results of spike tests for iAs(V), iAs(III), MMA(V), and DMA(V) with and without the addition of Pb in synthetic landfill leachate exhibited reasonable recoveries (i.e., 98-105%) after the spectral adjustment for the Pb interference.
authors.affiliation: Seoul Center, Korea Basic Science Institute, 126-16 5th Street, Anamdong, Sungbukgu, Seoul 136-713, Republic of Korea.
authors.forename: Jinsung
authors.initials: J
authors.lastname: An
authors.forename: Ki-Hyun
authors.initials: KH
authors.lastname: Kim
authors.forename: Joo-Ae
authors.initials: JA
authors.lastname: Kim
authors.forename: Hyeyeon
authors.initials: H
authors.lastname: Jung
authors.forename: Hye-On
authors.initials: HO
authors.lastname: Yoon
authors.forename: Jungju
authors.initials: J
authors.lastname: Seo
mesh_terms: D001149:Arsenates / Q000032:analysis; D001152:Arsenicals / Q000032:analysis; D018053:Arsenites / Q000032:analysis; D002101:Cacodylic Acid / Q000032:analysis* / Q000737:chemistry; D002412:Cations; D002851:Chromatography, High Pressure Liquid; D007854:Lead / Q000737:chemistry; D013058:Mass Spectrometry; D015203:Reproducibility of Results; D013052:Spectrometry, X-Ray Emission; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D001149:Arsenates; D001152:Arsenicals; D018053:Arsenites; D002412:Cations; D014874:Water Pollutants, Chemical; D007854:Lead; D002101:Cacodylic Acid; C020300:monomethylarsonic acid; C015001:arsenite; C025657:arsenic acid
keywords: Arsenic speciation; Dimethylarsinic acid; Spectral interference; Strong cation exchange disk; X-ray fluorescence spectrometry