In this article, we describe the analysis of aptamers for Hg2+ ions through CE with LIF (CE-LIF) detection using 2% poly(ethylene oxide) solutions containing OliGreen (fluorophore). In the presence of an EOF, DNA strands migrating against the EOF were detected at the cathode end Four DNA strands - T-33, T5C28. T5C5T23, and T15C5Ti3 - could not be separated through CE-LIF in the absence of Hg2+ At 0 3 mM Hg2+, however, all foul were partially separated within 20 min, with SDs of the migration times all being less than 2 5% From the CE, fluorescence, and ellipticity data, we concluded that the conformations of these four DNA strands all changed from random-coil to folded structures as a result of T-Hg2+-T bonding In addition, we found that this CE approach provided different electropherograms patterns for T-7, T-15, and T-33 in the absence and presence of Hg2+, indicating various interactions of the DNA strands with Hg2+ Using this simple, high-resolution CE approach, we also demonstrated that adenosine triphosphate has a stronger interaction with the adenosine triphosphate aptamer than with either the platelet-derived growth factor aptamer or T-33. This CE approach holds great potential for screening aptamers for small solutes, studying the catalytic activity of DNAzymes, and evaluating the biological functions of microRNA