Modular separation-based fiber-optic sensors for remote in situ monitoring

A modular separation-based fiber-optic sensor (SBFOS) with an integrated el ectronically controlled injection device is described for potential use in remote environmental monitoring. An SBFOS is a chemical monitor that integr ates the separation selectivity and versatility afforded by capillary elect rophoresis with the remote and high sensitivity capabilities of fiber-optic -based laser-induced fluorescence sensing. The detection module of the SBFO S accommodates all essential sensing components for dual-optical fiber, on- capillary fluorescence detection. An injection module, similar to injection platforms on micro-analysis chips, is also integrated to the SBFOS. The in jection module allows for electronically controlled injection of the sample onto the separation capillary. The design and operational characteristics of the modular SBFOS are discussed in this paper. A micellar electrokinetic capillary chromatography mode of separation is employed to evaluate the po tential of the sensor for in situ monitoring of neutral toxins (aflatoxins) . The analytical figures of merit for the modular SBFOS include analysis ti mes of between 5 and 10 min, separation efficiencies of approximately 10(4) theoretical plates, detection limits for aflatoxins in the mid-to-low nano molar range, and controllable operation that results in sensor performance that is largely immune to sample matrix effects.