| Abstract
| - Microdialysis sampling is a technique that has been usedfor in vivo and in vitro monitoring of compounds ofpharmaceutical, biomedical, and environmental interest.The coupling of a commercially available microdialysisprobe to a microchip-based capillary electrophoresis (CE)system is described. A continuously flowing dialysatestream from a microdialysis probe was introduced intothe microchip, and discrete injections were achieved usinga valveless gating approach. The effect of the appliedvoltage and microdialysis flow rate on device performancewas investigated. It was found that the peak area variedlinearly with the applied voltage. Higher voltages led tolower peak response but faster separations. Perfusion flowrates of 0.8 and 1.0 μL/min were found to provide optimalperformance. The on-line microdialysis/microchip CEsystem was used to monitor the hydrolysis of fluoresceinmono-β-d-galactopyranoside (FMG) by β-d-galactosidase.A decrease of the FMG substrate with an increase in thefluorescein product was observed. The temporal resolution of the device, which is dependent on the CE separation time, was 30 s. To the best of our knowledge, this isthe first reported coupling of a microdialysis samplingprobe to a microchip capillary electrophoresis device.
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