Eluents carbonate-based

Other eluent systems in suppressed ion chromatography are typically chosen based on specific separation requirements. For routine analysis of monovalent and divalent anions, carbonate-based eluents represent a reasonable alternative to hydroxide-based eluent systems. Carbonate eluents are simple to prepare and can be useful in cases where anion analysis is only occasionally performed. It must be kept in mind, however, that carbonate lowers the detection sensitivity for anionic species and introduces significant nonlinearity into the analysis. ... 

Figure 3.104 Separation of mono-, di-, and trivalent anions with a combined carbonate-based composition and concentration gradient. Column Alltech Novosep A-1 column dimensions 100 mm x 4.6 mm i.d. eluent ...

The unique selectivity of modern hyperbranched condensation polymers such as lonPac AS22 allows the simultaneous analysis of mineral acids and a wide variety of polarizable anions with a carbonate-based eluent under isocratic conditions in less than 30 min (Figure 3.131). Even strongly retained analytes such as perchlorate, thiosulfate, and chromate elute as symmetric peaks from this column. In contrast to the respective separation on an acrylate-based anion exchanger in Figure 3.130, fluoride is well separated from the system void. 

Figure 10.389 Separation of chloride and sulfate in a denatured bioethanol sample with a carbonate-based eluent. Separator column Metrosep A Supp 5 column dimensions ...

Uranium ores are leached with dilute sulfuric acid or an alkaline carbonate [3812-32-6] solution. Hexavalent uranium forms anionic complexes, such as uranyl sulfate [56959-61-6], U02(S0 3, which are more selectively adsorbed by strong base anion exchangers than are other anions in the leach Hquors. Sulfate complexes are eluted with an acidified NaCl or ammonium nitrate [6484-52-2], NH NO, solution. Carbonate complexes are eluted with a neutral brine solution. Uranium is precipitated from the eluent and shipped to other locations for enrichment. Columnar recovery systems were popular in South Africa and Canada. Continuous resin-in-pulp (RIP) systems gained popularity in the United States since they eliminated a difficult and cosdy ore particle/leach hquor separation step. 

The great interest in the possibility of replacing silici based bonded phases by carbon in RPC is understandable because the carbon is expected to be more stable toward aqueous eluents than the iflica-suppoited hydrocarbonaceous phases that are used almost exclusively today. Even if a carbonaceous sorbent with uniform surface and fovdrable porosity would be avaflable its stability may not live up to this expectation, however. The carbon surfoce is readily oxidized and can undergo other chemical transformations with concomitant changes in its retention properties. 

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