In addition to fundamental development, the continual improvement of micro-scale sample analysis must include treatment of real-world contamination issues such as food-borne toxins of natural and premeditated, hostile origins. The methodology for detecting food-borne mycotoxins, i.e., toxic molecules produced by various fungi living on grainstuffs and legumes, is broadly developed in the capillary electrophoresis (CE) literature. However, the advantages of the micro-scale platform have yet to be fully extended to this urgent field of analysis. Herein, we apply a hyphenation of microfluidic separations and vibrational spectroscopy detection to analyze certain mycotoxins while simultaneously testing the analytical merit of our novel method involving a microfluidic platform with metal-pliable polymer nanocomposite surface enhanced Raman spectroscopy (SERS) substrate fabricated directly into the device. The widespread development of microfluidics has allowed the extension of efficient separations, fluid handling, and hyphenation with many detection modes to a small, portable, highly controllable platform. SERS offers the advantage of obtaining vibrational spectroscopic information about analytes in aqueous matrices with negligible background. The mating of electrophoretic separations with vibrational spectroscopy on microfluidic devices will combine the chromatographic efficiency of CE with the analyte “fingerprinting” capability of detailed structural information. By utilizing SERS as a means of detection, this work will help yield redress for the hindrances of electrophoretic separations, including uncertainty in analyte band identification due to changing migration times as well as compromised detection sensitivity for non-fluorescent analytes. Neither chromatographic nor spectroscopic performance substantially suffers with nanocomposite integration; our systems show efficiencies of 350,000 plates/meter and spectral reproducibility showing <10% RSD among devices. Considerable investigation has led to identification of solvent and micellar electrokinetic capillary chromatography (MECC, used to separate neutral mycotoxins) conditions amenable to both separation and SERS sensing, as partitioning of analytes onto the nanocomposite surface is crucial to detection.
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Back to The 56th Southeast Regional Meeting 2004 (November 10-13, 2004)