Abstract: We present a newly-developed separations-based fiberoptic sensor (SBFOS) for biomedical applications. The sensor features a linear 10 cm effective length section of capillary coupled with a single optical fiber for laser-induced fluorescence (LIF) detection of fluorescently-labeled analytes separated by capillary electrophoresis (CE). The single optical fiber, arranged perpendicular to and touching the capillary, transmits both laser excitation to the sensor and analytical signal from the sensor to a PMT-based detection system. The resulting compact, robust design may prove to be an attractive alternative to conventional CE laboratory systems due to the portability and potential for automation and multiplexing. The sensor has been evaluated with size selective separations of phi X- 174 HaeIII digest DNA samples. Baseline resolution for fragments differing by 10 base pairs was routinely observed in separations requiring approximately 10 min. This short analysis time, combined with rapid sensor regeneration capability, enabled the temporal analysis of a digestion of phi X-174 phage DNA by HaeIII restriction enzyme. The use of viscous matrices permits sensor operation in any orientation without introducing complications associated with gravity-driven hydrostatic flow. Relative standard deviations in migration rates of the phi X-174 DNA fragments have generally been less than 5%. Furthermore, efficiencies of up to 2.5 million plates/m have been observed, giving the compact sensor a separation quality which is competitive with larger conventional CE systems. (C) 1999 Elsevier Science B.V. All rights reserved

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