Document Detail

Low-picomolar limits of detection using high-power light-emitting diodes for fluorescence.
MedLine Citation:
PMID:  16633580     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Fluorescence detectors are ever more frequently being used with light-emitting diodes (LEDs) as the light source. Technological advances in the solid-state lighting industry have produced LEDs which are also suitable tools in analytical measurements. LEDs are now available which deliver 700 mW of radiometric power. While this greater light power can increase the fluorescence signal, it is not trivial to make proper use of this light. This new generation of LEDs has a large emitting area and a highly divergent beam. This presents a classic problem in optics where one must choose between either a small focused light spot, or high light collection efficiency. We have selected for light collection efficiency, which yields a light spot somewhat larger than the emitting area of the LED. This light is focused onto a flow cell. Increasing the detector cell internal diameter (i.d.) produces gains in (sensitivity)3. However, since the detector cell i.d. is smaller than the LED spot size, scattering of excitation light towards the detector remains a significant source of background signal. This can be minimized through the use of spectral filters and spatial filters in the form of pinholes. The detector produced a limit of detection (LOD) of 3 pM, which is roughly three orders of magnitude lower than other reports of LED-based fluorescence detectors. Furthermore, this LOD comes within a factor of six of much more expensive laser-based fluorescence systems. This detector has been used to monitor a separation from a gel filtration column of fluorescently labeled BSA from residual labeling reagent. The LOD of fluorescently labeled BSA is 25 pM.
Ebbing P de Jong; Charles A Lucy
Publication Detail:
Type:  Journal Article     Date:  2006-04-05
Journal Detail:
Title:  The Analyst     Volume:  131     ISSN:  0003-2654     ISO Abbreviation:  Analyst     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-04-24     Completed Date:  2007-11-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372652     Medline TA:  Analyst     Country:  England    
Other Details:
Languages:  eng     Pagination:  664-9     Citation Subset:  -    
Department of Chemistry, Gunning/Lemieux Chemistry Centre, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
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