Anions mobile trace analysis

Figure 11 Analysis of a human serum by capillary zone electrophoresis with inherent transient isotachophoretic stacking of analytes. The BGE co-ion, mandelate, acts as terminator in the system where chloride surplus present naturally in the sample acts as the leading type stacker and conditions for transient isotachophoretic stacking of phosphate, citrate, malate, and acetoacetate with mobilities between chloride and mandelate are ensured. BGE is composed of 5 mmol r mandelic acid-h e-aminocaproic acid, pH 3.8. Reprinted with permission from Kfivankova L, Pantuckova P, Gebauer P, et al. (2003) Chloride present in biological samples as a tool for enhancement of sensitivity in capillary zone electrophoretic analysis of anionic trace analytes. Electrophoresis 24 515.)...

Because modem anion exchangers are solvent-compatible, solvents can also be used to alter selectivity. Figure 9-17 illustrates the gradient elution of chloro-and bromo-acetic acids on lonPac AS 11 with a constant content of methanol in the mobile phase. Even though separations of this kind are promising, it is questionable whether the necessary sensitivity for water analysis can be achieved with suppressed conductivity detection. Thus, the method of IC-MS via an electrospray interface introduced by Hashimoto and Otsuki [57] creates a lot of interest. With this method the authors analyzed nine different chloro- and bromo-acetic acids at trace levels. However, the method requires analyte extraction with methyl-tert.-butyl ether. Based on a 200-mL water sample, detection... 

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