Optical fiber light‐emitting diode‐induced fluorescence detection for capillary electrophoresis

Abstract

A highly sensitive optical fiber light-emitting diode (LED)-induced fluorescence detector for CE has been constructed and evaluated. In this detector, a violet or blue LED was used as the excitation source and an optical fiber with 40 microm OD was used to transmit the excitation light. The upper end of the fiber was inserted into the separation capillary and was situated right at the detection window. Fluorescence emission was collected by a 40 x microscope objective, focused on a spatial filter, and passed through a cutoff filter before reaching the photomultiplier tube. Output signals were recorded and processed with a computer using in-house written software. The present CE/fluorescence detector deploys a simple and inexpensive optical system that requires only an LED as the light source. Its utility was successfully demonstrated by the separation and determination of amino acids (AAs) labeled with naphthalene-2,3-dicarboxaldehyde (NDA) and FITC. Low detection limits were obtained ranging from 17 to 23 nM for NDA-tagged AAs and 8 to 12 nM for FITC-labeled AAs (S/N=3). By virtue of such valuable features as low cost, convenience, and miniaturization, the presented detection scheme was proven to be attractive for sensitive fluorescence detection in CE.

Enhanced Indirect Fluorescence Detection of p-Nitrophenol, 2,4-Dinitrophenol and Trinitrophenol by Micellar Electrokinetic Capillary Chromatography with In-column Optical-fiber LED-induced Fluorescence Detection

“…The in-column fiber-optics LED-IF for CE has been previously described. 25,27,28 To further improve the design, a fiber coupling device was used to match the precision translation stage (Fig. 1a) with the optical fiber.…”

“…The in-column fiber optics LED-IF detection system was successfully applied to other applications in our previous work. 24,25 The detector uses a simple and inexpensive optical system that can avoid light reflection and scattering on the capillary surface, so that low background noise is maintained with a concomitant improvement of the S/N in the detection. 26 The major attributes of our work are simpler detector set-up, cost-effective, the flexibility of using different excitation wavelengths, and higher detection sensitivity.…”

Portable capillary-based (non-chip) capillary electrophoresis

“…The wavelength range available covers almost the whole spectrum from near IR [125] down to 405 nrn [126] and 375 nm [127]. As smaller dimensions of the device can be reached when employing LEDs and LDs as excitation light sources, the possibility of incorporation into the P-CE designs increases [128][129][130]. Other types of OD have been described.…”

A compact and highly sensitive light-emitting diode-induced fluorescence detector for capillary flow systems

“…In order to achieve light focusing, optical lens were often preferred to be used in LED-FDs studies, e.g., lens group and objective [8][9][10]. It did bring some focusing effect, but increase optical path and reflectance, take a tedious calibration process, and show tight position tolerance.…”