A compact and highly sensitive light-emitting diode-induced fluorescence detector for capillary flow systems

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Instrumentation

Background:

• Developing sensitive and compact fluorescence detection systems is crucial for various analytical applications.
• Existing fluorescence detectors can be bulky and expensive, limiting their widespread use.
• Optimizing optical configurations and excitation sources can enhance detector performance.

Purpose of the Study:

• To construct and evaluate a compact and highly sensitive light-emitting diode-induced fluorescence detector (LED-FD).
• To assess the performance of the LED-FD for trace analysis using flow injection analysis (FIA).
• To compare the developed LED-FD with commercial fluorescence detectors.

Main Methods:

• A compact LED-FD was designed, integrating an LED excitation source, filter, pinhole, and capillary flow cell without lenses or fibers.
• The system's performance was evaluated using flow injection analysis (FIA) of sodium fluorescein solutions.
• Limit of detection (LOD), signal-to-noise ratio (SNR), linearity, repeatability, and reproducibility were determined.

Main Results:

• The LED-FD achieved a limit of detection (LOD) of 0.75 nM (SNR=3) for sodium fluorescein.
• A 3.5-fold enhancement in signal-to-noise ratio (SNR) was observed compared to previous designs.
• Linear response was obtained in the 2-200 nM concentration range (R=0.9993), with excellent repeatability (≤2.0% R.S.D.) and reproducibility (≤2.2% R.S.D.).
• The developed LED-FD demonstrated comparable fluorescence signal intensity to commercial detectors.

Conclusions:

• The constructed compact LED-FD is a highly sensitive and robust instrument for fluorescence detection.
• The simplified optical design offers significant improvements in SNR and performance.
• This LED-FD presents a cost-effective and efficient alternative to commercial fluorescence detectors for analytical applications.