Fluorescence microscopic spectral study of fluorescein and some amino acids

Narahari V. Joshi; Virginia Otero de Joshi; Nestor Rodrigues; Luis Hernandes

doi:10.1117/12.206031

3 April 1995 Fluorescence microscopic spectral study of fluorescein and some amino acids

Narahari V. Joshi, Virginia Otero de Joshi, Nestor Rodrigues, Luis Hernandes

Proceedings Volume 2386, Ultrasensitive Instrumentation for DNA Sequencing and Biochemical Diagnostics; (1995) https://doi.org/10.1117/12.206031
Event: Photonics West '95, 1995, San Jose, CA, United States

Abstract

A conventional collinear laser induced fluorescence detection system for capillary electrophoresis was modified by replacing a GaAs photomultiplier by a Charge coupled Device which was operated at liquid nitrogen temperature. This permits longer exposure time to collect the weak radiation and hence extends the limit of detection and spectral analysis of lower concentration of biological active molecules. Using the above technique, and passing the solution through a capillary of 20 micrometers inside diameter, we have recorded fluorescence spectra of biological important molecules such as Arginine, Glutamate and Glutamine; all of them were derivatized with Fluorescein Isothiocyanate (FITC) isomer I. Spectra of FITC as a function of the pH were examined to lower the detection limit. The concentration of the molecules was as low as 10^-14 M. All the spectra recorded lied in the expected region (510 nm to 550 nm) and showed considerable similarity. The spectrum of low concentration of molecules provides significant information as the intensity of intra-molecular interaction is reduced. The recorded spectra gave information about the distribution of vibrational states near S₀ and S₁ levels.

Citation Download Citation

Narahari V. Joshi, Virginia Otero de Joshi, Nestor Rodrigues, and Luis Hernandes "Fluorescence microscopic spectral study of fluorescein and some amino acids", Proc. SPIE 2386, Ultrasensitive Instrumentation for DNA Sequencing and Biochemical Diagnostics, (3 April 1995); https://doi.org/10.1117/12.206031

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