Capillary electrochromatography gradient elution

MC Breadmore, M Macka, N Avdalovic, PR Haddad. On-capillary ion-exchange preconcentration of inorganic anions in open-tubular capillary electrochromatography with elution using transient-isotachophoretic gradients. 2. Characterization of the isotachophoretic gradient. Anal Chem 73 820-828, 2001. 

M.C. Breadmore, A.S. Palmer, M. Curran, M. Macka, N. Avdalovic and PR. Haddad, On-column ion-exchange of inorganic anions in open tubular capillary electrochromatography with elution using transient-isotachophoresis gradients. 3. Implementation and method development. Anal. Chem., 74, 2112-2118, 2002. 

Taylor, M. R., Teale, P., Westwood, S. A., and Perrett, D. (1997). Analysis of corticosteroids in biofluids by capillary electrochromatography with gradient elution. Anal. Chem. 69, 2554-2558. 

Fig. 10.17. Capillary electrochromatography of PTH-amino acids with gradient elution. Column, 207 (127) mm x 50 pm i.d. packed with 3.5 pm Zorbax ODS particles, 80 A pores. Starting eluent (A), 5 mM phosphate, pH 7.55, 30% acetonitrile gradient former (B), 5 mM phosphate, pH 7.55, 60% acetonitrile flow-rate (through inlet reservoir), 0.1 ml/min gradient, 0-100% B in 20 min voltage 10 kV current, 1 pA temperature, 25°C UV detection at 210 nm electrokinetic injection, 0.5 s, 1 kV. Peaks in order of elution formamide PTH-asparagine PTH-glutamine PTH-threonine PTH-glycine PTH-alanine PTH-tyrosine PTH-valine PTH-proline PTH-tryptophan PTH-phenyialanine PTH-isoleucine PTH-leucine. The concentration of the PTH-amino acids dissolved in the mobile phase was 30-60 pg/ml. Reprinted with permission from Huber et al. [68]. Copyright 1997 American Chemical Society.

Taylor et al. [39,56] analyzed a mixture of corticosteroids in extracts of equine urine and plasma. Gradient elution was used to facilitate trace enrichment at the head of the column. Huber et al. [36] presented another illustration for the use of capillary electrochromatography with gradient elution. Five steroid hormones were separated by using a capillary column packed with 6-pm Zorbax ODS stationary phase. 

Gfrorer, P., et al.. Gradient elution capillary electrochromatography and hyphenation with nuclear magnetic resonance, Electrophoresis, 20, 3, 1999. 

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