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Electroosmotic flow-balanced isotachophoretic stacking with continuous electrokinetic injection for the concentration of anions in high conductivity samples.

Journal of chromatography. A (2010-05-11)
Michael C Breadmore
ABSTRACT

An EOF counter-balanced ITP boundary has been used to stack anions from high conductivity samples during continuous electrokinetic injection of the sample. In a polystyrenesulfonate/poly(diallyldimethylammonium chloride) polyelectrolyte coated capillary, the time at which the ITP boundary exited the capillary could be prolonged by balancing the movement of the boundary with the EOF. Using a bis-tris-propane electrolyte, the ITP boundary was removed from the capillary within 7min, while when using triethanolamine the ITP boundary was still at 30% of the capillary after 2h of injection. Using these systems, the sensitivity of a mixture of simple organic acids in 100mM Cl(-) was improved by 700-800-fold using bis-tris-propane with a whole-capillary injection of the sample and 5min of electrokinetic injection at +28kV, and 1100-1300-fold using triethanolamine and 60min of electrokinetic injection under the same conditions. The potential of the method to be applicable to high conductivity samples was demonstrated by stacking a whole capillary filled with urine spiked with naphthalenedisulfonic acid, with limits of detection 450 times lower than those achievable with a normal hydrodynamic injection.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
BIS-TRIS propane, ≥99.0% (titration)
Sigma-Aldrich
BIS-TRIS propane, BioPerformance Certified, suitable for cell culture, ≥99.0%
Sigma-Aldrich
BIS-TRIS propane, BioXtra, ≥99.0% (titration)