Fluorescence correlation spectroscopy for rapid multicomponent analysis in a capillary electrophoresis system

Area of Science:

• Analytical Chemistry
• Biophysical Chemistry
• Spectroscopy

Background:

• Fluorescence Correlation Spectroscopy (FCS) is a sensitive optical technique for analyzing static solutions based on analyte diffusion times.
• Multicomponent analysis in ultradilute solutions presents challenges for traditional methods.

Purpose of the Study:

• To introduce and validate a novel technique combining capillary electrophoresis (CE) and fluorescence correlation spectroscopy (CE/FCS) for multicomponent analysis.
• To demonstrate the applicability of CE/FCS for analyzing ultradilute solutions without chemical separation.

Main Methods:

• CE/FCS measures analyte transit times through a microcapillary under an applied electric field.
• Analyte separation is achieved by exploiting differences in electrophoretic mobilities, not diffusion times.
• The technique was applied to analyze mixtures of Rhodamine 6G and labeled nucleotides in subnanomolar concentrations.

Main Results:

• CE/FCS successfully performed multicomponent analysis without prior chemical separation.
• The method accurately determined relative concentrations of analytes in ultradilute aqueous solutions (subnanomolar).
• Analyte concentrations below 10(-11) M were detected with analysis times under tens of seconds.

Conclusions:

• CE/FCS is a highly sensitive and rapid technique for multicomponent analysis, especially in ultradilute solutions.
• This method overcomes limitations of diffusional FCS by not requiring significant differences in diffusion coefficients.
• CE/FCS offers a powerful new approach for studying complex systems that are difficult to analyze with existing techniques.