Multiplexed detection methods for microchannel and conventional capillary electrophoresis

Improving detection techniques for capillary and microchannel electrophoresis is a key challenge. The difficulty stems from the narrow capillaries utilized for conventional CE and the reduced inner diameters of the separation channel in MCE. These small dimensions yield short optical pathlengths which create an obstacle in collecting signal from the separated analytes. Also, small, sometimes very dilute, sample volumes are being analyzed in these narrow capillaries creating an even greater detection challenge. The utilization of multiplex detection methods for CE and MCE separations to improve detection are described.;The term multiplex is based on collecting signal from 'multiple detection windows' rather than a single window. Encoded detection techniques are multiplexed detection methods that can significantly improve detection. These encoded data is subsequently decoded post data collection for improving detection. Two types of encoded detection techniques, the Shah convolution Fourier transform (SCOFT) and the Hadamard transform (HT), are performed with a custom-built laser-induced fluorescence detection system with a multichannel detector.;In SCOFT, the convolution detection is performed by sampling an analyte band migrating along the separation channel at its characteristic speed at evenly spaced regions. The sum of these sample peaks is the time-domain signal that can be Fourier transformed allowing the analyte to be viewed in terms of its characteristic velocity. Greater S/N enhancements and flexibility for this encoded detection format are illustrated.;The HT detection technique is based on a weighing design principle of accurately weighing a number of objects in groups, rather than one at a time. After decoding, the mean square error can be significantly reduced and the S/N enhanced. Analytical signals from the separated analytes are collectively measured generating an enhancement in S/N after the decoding process. The extension of this multiplexed method towards absorbance detection in conventional CE for biological samples is also presented.;The multiplex detection research described has provided significant detection enhancements for CE and MCE. This research has improved detection of less concentrated, small volume samples separated in the narrow channel geometry of the microchannels and capillaries. The multiplexed methods described in this research will aid in the improvement of separation analysis.