UV light-emitting diode-induced fluorescence detection combined with online sample concentration techniques for capillary electrophoresis

Yen Sheng Chang, Chun Min Shih, Cheng Huang Lin

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The application of an ultraviolet (UV) light-emitting diode (LED) to on-line sample concentration/fluorescence detection in capillary electrophoresis (CE) is described. The utility of a UV-LED (peak emission wavelength at 380 nm, ≃2 mW) for fluorescence detection was demonstrated by examining both a naturally fluorescent (riboflavin) compound and a non-fluorescent compound (tryptophan), respectively. The detection limit for riboflavin was determined to be 0.2 ppm by the normal MEKC mode, which was improved to 3 - 7 ppb when dynamic pH-junction technique was applied. On the other hand, the detection limit of the tryptophan derivative was determined to be 1.5 ppm using the MEKC mode, which was improved to 3 ppb when the sweeping-MEKC mode was applied. In an analysis of an actual sample, the concentrations of riboflavin in beer, and tryptophan in urine and milk samples were determined, respectively. 2006

Original languageEnglish
Pages (from-to)235-240
Number of pages6
JournalAnalytical Sciences
Issue number2
Publication statusPublished - 2006 Feb


ASJC Scopus subject areas

  • Analytical Chemistry

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