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United States Department of Agriculture

Agricultural Research Service

Research Project: NOVEL TECHNOLOGIES AND TECHNIQUES FOR THE DETECTION OF RESIDUES, TOXINS, AND OTHER CHEMICALS IN FOODS

Location: Residue Chemistry and Predictive Microbiology

Title: Fluorometer with a quartz-rod waveguide-integrating sphere configuration to measure evanescent-field luminescence

Author
item Chen, Guoying

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 22, 2010
Publication Date: July 13, 2010
Citation: Chen, G. 2010. Fluorometer with a quartz-rod waveguide-integrating sphere configuration to measure evanescent-field luminescence [Abstract]. Symposium on Luminescence Spectrometry.

Technical Abstract: A fluorometer was designed to measure evanescent-field luminescence. A quartz-rod waveguide (d = 2 mm) was installed coaxally inside a cylindrical flow-through cell (id = 2.3 mm, od = 6.3 mm, l = 116 mm). An excitation beam from a UV LED or a miniature xenon flashlamp was focused by a ball lens and launched into the waveguide. An integrating sphere (D = 105 mm) surrounded the waveguide-cell assembly to collect the luminescence signal originated from the evanescent field. After multiple diffusive reflections, the signal was finally coupled to a photomultiplier tube by a short waveguide (d = 5 mm) embedded on the wall perpendicular to the cell axis. This configuration improved collection efficiency leading to enhanced sensitivity. This fluorometer was operated in a flow-injection analysis mode under the control of a custom LabVIEW program. Its application included analysis of several veterinary drug residues in foods based on steady-state fluorescence or lanthanide-sensitized luminescence. The optical characteristics and analytical performance of this configuration were discussed and compared with those of other geometries in which a tapered or planar waveguide was used as the sensing element.

Last Modified: 7/24/2014
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