Directly Detectable Spacers for Indirect Detection of Analytes

This invention enables the high-sensitivity, high-resolution stacking, separation, and fluorescence-based detection of non-fluorescent analytes in any electrophoresis platform. Sample analytes are mixed with a suitable "ladder" of fluorescent isotachophoretic spacer molecules of known mobility and initial concentration. Upon isotachophoretic stacking and separation, spacers stack are directly detectable. Signal decreases (i.e., "dips" in electropherograms) in identifiable locations within the spacer ladder unambiguously identify the presence of analytes and bound their mobility within a narrow, known range. Both analyte mobility and initial concentration can be determined (indirectly but accurately) from spacer signals. The technique can also be applied to other detection modalities such as UV absorption and amperometric detection by identifying spacers with strong signals in such modalities, and using these (absorption and/or amperometric) spacers as an indirect detection of analytes with weak or undetectable signals.

The inventors have experimentally demonstrated the efficacy of the technique
and are currently performing a parametric study to quantify its performance.