Anions speciation analysis

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... 

Anion exchange chromatography coupled with ICP MS was used in the simultaneous speciation analysis of As, Se, Sb and Te compounds in extracts of fish [230]. Size exclusion chromatography (SEC) coupled with specific detectors is frequently used to analyse species of trace elements in protein-rich materials, such as extracts of meat and plant tissues. For instance, SEC hyphenated with ICP MS was used for the speciation analysis of Cu and Zn in samples of leguminous plants [191]. The same technique was applied to the speciation analysis of Cu, Cd, Zn, Se, As and Ca in fish [220] and Fe, Zn, Cu, Ag, Cd, Sn and Pb in mussels [189]. SEC HPLC coupled with GF AAS mmed out to be very useful for determining levels of Fe species in baby food [312]. With gel permeation chromatography (GPC) GF AAS, the speciation forms of Cd were determined in two kinds of vegetables contaminated with this element [216]. 

Separation equipment such as HPLC or CE has been coupled to atomic spectrometers via USNs to enable the determination of inorganic and organometallic analytes. Thus, antimony speciation analysis — inorganic Sb(lll) and Sb(V), as well as TMSbCl2 — was accomplished by separation by anion exchange chromatography and subsequent insertion of the eluent into the plasma of an ICP-MS instrument using USNn [28]. 

C. Pons, R. Forteza, V. Cerda, The use of anion-exchange disks in an optrode coupled to a multi-syringe flow-injection system for the determination and speciation analysis of iron in natural water samples, Talanta 66 (2005) 210. 

The use of HPLC coupled to an element-specific detector for speciation analysis has been reviewed, as have the HPLC methods for some specific elemental species. " A representative selection of speciation methods based on HPLC separation is given in Table 6. The main separation modes used are ion exchange (anion and cation) and... 

Separation is performed where the determination of different species cannot be performed with sufficient selectivity, e.g. when an element-selective detector is used (e.g. AAS). The separation of chemical species of elements can only be performed by techniques which do not destroy the chemical forms, e.g. by heat-induced decay of the species. Except for cold trapping methods (for water analysis), the separation is performed after extraction and suitable clean-up of the extract. Three basic methods are generally used in speciation analysis chromatography (e.g. anion exchange, ion pairing reversed phase liquid... 

The most commonly used methods for speciation analysis of iodine in tissues and food are chromatographic techniques, such as anion exchange, size exclusion and reverse-phase chromatography, coupled with ICP-MS detection. 

The application of LC online with ESTMS is especially attractive for the speciation analysis of Cd and Zn complexes. Metallated complexes such as MTs may suffer from several artifacts in their chromatographic separation due to the presence of those metals. For instance, the presence of other metals may modify the retention of the complex Cd-Zn-MTs on a RP column. As an alternative, ESI-MS with pH control can help in the analysis of metals in native and reconstituted metalloproteins, in order to exactly elucidate which biocompoimd binds Cd, how many atoms of Cd per bioHgand molecule are boimd, and what is the combination with other metals (e.g., Zn and Cu) in such molecules. In this line, samples of rabbit liver and horse kidney MTs (previously isolated by SEC and anionic-exchange chromatography) were analyzed imder pH selected conditions. In moderately acidic (pH 4.0) and neutral (pH 6-7) media, the complexes of MTs with Cd and Zn retain... 

CE-MS has been used in analyses of anions and cations as a method simultaneously providing positive identification and quantitation. CE-ESI MS is particularly well suited for analyses of quaternary ammonium salts. Speciation analysis of As can be carried out using a CE-ICP-MS. Problems in interfacing the ICP-MS detection to CE are associated with low flow rates and small samples analyzed. Detection limits in ppb region can be attained, using postcapillary hybridization prior to ICP-MS. 

Capillary electrophoresis (CE), as a complement to other separation methods, is widely applied in analytical laboratories. This method is versatile for diverse analytes because of its extraordinary resolution power of up to 500000 theoretical plates, and its ability to separate anions, cations, and neutral molecules in a single analysis. Because the coupling of CE to ICP-MS is introduced into speciation analysis, especially in recent years, several interfaces of CE-ICP MS have been developed, thus the approach has been proven to be potential for protein quantification. ... 

Rodriguez-cea, A., Fernandez de la Campa, M.R., Blanco-Gonzdlez, E., Andon Ferndndez, B., and Sanz-Medel, A. (2003) Metal speciation analysis in eel Anguilla an-guilla) metallothioneins by anionic exchange-EPLC-isotope dUution-ICP-MS. 7. Anal At. Spectrom., 18,1357-64. 

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