title: A compact and highly sensitive light-emitting diode-induced fluorescence detector for capillary flow systems.
abstract: A compact and highly sensitive light-emitting diode-induced fluorescence detector (LED-FD) was constructed and evaluated. The LED excitation beam was restricted by a 200 μm diameter pinhole on a 55 μm thick lighttight film. The LED, excitation filter, pinhole, and capillary flow cell were placed tightly against each other without either optical lens or excitation fiber. The performance of the LED-FD was evaluated by flow injection analysis (FIA) of sodium fluorescein solution. The limit of detection (LOD) was determined as 0.75 nM (SNR=3). Compared with our previous work, a 3.5-fold enhancement on the signal-to-noise ratio (SNR) was obtained. The system exhibited linear responses in the concentration range of 2-200 nM (R=0.9993). The error of repeatability was within 2.0% R.S.D. on peak height in a ten-repeated injection of 5 nM solution. The reproducibility between devices was within 2.2% R.S.D. on peak height of 10nM fluorescein solution. Finally, the LED-FD was compared with commercial fluorescence detector, and similar fluorescence signal intensity was obtained.
authors.affiliation: Department of Instrumentation & Analytical Chemistry, Key Lab of Separation Science for Analytical Chemistry of CAS, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Geng
authors.forename: Dapeng
authors.initials: D
authors.lastname: Wu
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Guan
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry; D005591:Chemical Fractionation / Q000295:instrumentation* / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D017022:Flow Injection Analysis; D019793:Fluorescein / Q000737:chemistry; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes; D008027:Light; D057230:Limit of Detection; D055096:Optical Devices; D015203:Reproducibility of Results; D012212:Rheology; D059629:Signal-To-Noise Ratio; D013050:Spectrometry, Fluorescence
chemical_list: D000596:Amino Acids; D005456:Fluorescent Dyes; D016650:Fluorescein-5-isothiocyanate; D019793:Fluorescein