RESUMEN

Inexpensive and disposable polyester microchips were fabricated through photolithographic and wet-chemical etching procedure, followed by replication using an imprinting method at room temperature. Laboratory-scale laser-induced fluorescence equipment was employed as a detection system. The generation of electroosmotic flow (EOF) on the polyester channels was discussed in this paper. Surfactants in the running buffer had a significant effect on the EOF depending on their types. The epsilon potential of the electric double layer formed by adsorbing sodium lauryl sulfate molecules on the wall of polyester channels seemed to be constant within the buffer pH investigated. EOF could also be suppressed to zero by adding polyoxyethylene 23 lauryl ether into the running buffer. The separation of two laser dyes was obtained using polyester chips through both micellar electrokinetic chromatography and capillary zone electrophoresis. The polyester channels modified with 10-undecen-1-ol exhibited a dramatically high-separation efficiency compared with the conventional fused-silica capillary tubes.

Asunto(s)

Electroforesis Capilar/métodos , Poliésteres/química , Concentración de Iones de Hidrógeno , Ósmosis

RESUMEN

Thermal lens spectroscopy was combined with total internal reflectance spectroscopy to develop a novel, highly sensitive analytical method that can detect nonfluorescent as well as fluorescent analytes at surfaces and interfaces. It was verified that when the total internal reflection method is coupled with thermal lens spectroscopy (TIR-TLS), the thermal lens effect is induced by only the evanescent wave. The ability of depth profiling was shown. The detection limit of TIR-TLS was at an absorbance of 3.0 x 10(-5) unit for Sudan II acetone solution, which is better than that of attenuated total reflection by a factor of hundreds. In addition, the adsorption of acridine orange on silanol groups on a glass surface could be monitored directly by TIR-TLS, and the adsorption isotherm agreed well with Langmuir's model. The dependence of surface density of anionic silanol groups on pH was determined by TIR-TLS measurements of aqueous acridine orange solutions buffered in the pH range between 2.7 and 11.5.