Temperature gradient focusing with field-amplified continuous sample injection for dual-stage analyte enrichment and separation

Anal Chem. 2007 Aug 15;79(16):6201-7. doi: 10.1021/ac070689r. Epub 2007 Jul 7.

Abstract

We describe the serial combination of temperature gradient focusing (TGF) and field-amplified continuous sample injection (FACSI) for improved analyte enrichment and electrophoretic separation. TGF is a counterflow equilibrium gradient method for the simultaneous concentration and separation of analytes. When TGF is implemented with a low conductivity sample buffer and a (relatively) high conductivity separation buffer, a form of sample enrichment similar to field-amplified sample stacking (FASS) or field-amplified sample injection (FASI) is achieved in addition to the normal TGF sample enrichment. FACSI-TGF differs from FASI in two important respects: continuous sample injection, versus a discrete injection, is utilized; because of the counterflow employed for TGF, the stacking interface exists in a pseudo-stationary region outside of the separation column. Notably, analyte concentration enrichment factors greater than the ratio of separation and sample conductivities (gamma) were achieved in this method. For gamma=6.1, the concentration factor for one model analyte (Oregon Green 488) was found to be 36-fold higher with FACSI-TGF as compared to TGF without FACSI. A separation of five fluorescently labeled amino acids is also demonstrated with the technique, yielding an average enrichment of greater than 1000-fold.

Publication types

  • Evaluation Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Buffers
  • Electric Conductivity
  • Electrophoresis / instrumentation
  • Electrophoresis / methods*
  • Electrophoresis / standards
  • Temperature*

Substances

  • Buffers