Speciation anion-exchange

On-line anion exchange LC/ICP-MS methods for selenium and chromium speciation have been published [30], In studies of selenium speciation in environmental samples LC/ICP-MS and LC/ ESI-MS methods have been used for the determination of both inorganic and organic selenium species [43]. For the determination of methyl selenide, strong anion exchange and RP chromatography have been employed [43], while for the determination of seleno-aminoacids, IP RP chromatography with on-line detection based on ICP-MS has been successfully employed [44],... 

Magnesium speciation (Section ni.A) in serum was carried out using an anion exchange column for protein separation, with mobile phase at pH 7.4 the effluent was collected in an automatic fraction collector. On-line quantitation of the protein fractions was carried out by DA-UVD, and Mg determination was carried out from the automatic sampler in a GFAAS apparatus, measuring at 202.8 nm . ... 

A. Woller, H. Garraud, J. Boisson, A. M. Dorthe, P. Fodor and O. F. X. Donard, Simultaneuous speciation of redox species of arsenic and selenium using an anion-exchange microbore column coupled with a micro-concentric nebuliser and an inductively coupled plasma mass spectrometer as detector, J. Anal. At. Spectrom., 13, 1998, 141-149. 

J. A. Day, M. Montes-Baydn, A. P. Vonderheide, and J. A. Caruso, A Study of Method Robustness for Arsenic Speciation in Drinking Water Samples by Anion Exchange HPLC-ICP-MS, Anal. Bioanal. Chem. 2002,373, 664. 

Pantsar-Kallio and Manninen [85] optimised a unique coupled cation- and anion-exchange chromatographic system for Cr speciation. The need for Cr(III) species conversion by oxidation was eliminated by the use of dilute nitric acid eluents. Detection limits using the system were 0.3 pig l-1 for Cr(III) and 0.8 pug 1—1 for Cr(VI) in lake water samples. 

Tomlinson and Caruso [28] also performed the speciation of Cr(III) and (VI) using a Dionex AS-11 anion-exchange microbore column and 6 mM 2,6-PDCA-8.6 mill lithium hydroxide mobile phase. A thermospray source was used as the interface between LC and ICP-MS. Absolute limits of detection were at the pg level for both species using this instrument assembly. 

Liang L., S. Mo, P. Zhang, et al. 2006. Selenium speciation by high-performance anion-exchange chro-matography-post-column UV irradiation coupled with atomic fluorescence spectrometry. J. Chromatogr. A 1118 139-143. 

Aggett and Kadwani [13] report the development and application of a relatively simple anion exchange method for the speciation of arsenate, arsenite, monomethylarsonic acid and dimethylarsinic acid. As these four arsenic species are weak acids the dissociation constants of which are quite different it seemed that separation by anion exchange chromatography was both logical and possible. 

Chromium speciation by using anion-exchange chromatography has also received much attention in recent years because the element is both essential to humans and toxic in large doses [62-66]. Cr (III) and Cr (VI) may be separated by... 

Heumann et al. [67] used anion-exchange chromatography to speciate iodide and iodate in mineral water samples. Iodate concentrations were in the range 0.5-20 mg/mL and iodide concentrations were 0.1-5 ng/mL. 

Wine is a very complex matrix and the accurate, selective determination of species constitutes a challenge for analytical chemists. Furthermore, the speciation analysis of metals bound to biological ligands is a subject of increasing interest since complexation may reduce their toxicity and bioavailability. There is a limited number of studies concerning the speciation analysis of metals or metalloids in wines. Arsenite, arsenate, MMA, and DMA were separated in less than 10 min by means of an anion-exchange column [88], Arsenic species detection was accomplished by the direct coupling of the column effluent to an HG system and AFS was used for detection. LoDs in white wine were 0.16, 0.33, 0.32, and 0.57 ng ml-1 for As(III), DMA, MMA, and As(V), respectively. In real samples... 

Anion-exchange (AE) HPLC-ICP-MS seems to be the most attractive technique for a comprehensive speciation analysis of organo-As species in biological materials. An example chromatogram for such an analysis is shown in Figure 16.4. Cation-exchange HPLC has often been used in parallel to AE-HPLC to conFrm... 

A. Polatajko, J. Szpunar, Speciation of arsenic in chicken meat by anion-exchange liquid chromatography with inductively coupled plasmaDmass spectrometry, J. AOAC Int, 87 (2004), 233D237. 

B. Michalke, P. Schramel, Manganese speciation in human milk using size exclusion chromatography combined with strong anion exchange chromatography and inductively coupled plasma mass spectrometry detection, J. Anal. Atom. Spectrom., 19 (2004), 121-128. 

S. McSheehy, J. Szpunar, Speciation of arsenic compounds in edible algae by bidi-mensional size-exclusion anion-exchange HPLC with dual ICP-Ms and electrospray MS/MS detection, J. Anal. Atom. Spectrom., 15 (2000), 79- 87. 

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