A two-point fluorescence detection flow cell with empirical calibration for high optical density analysis

Area of Science:

• Analytical Chemistry
• Biophotonics
• Spectroscopy

Background:

• Inner-filter effects (IFEs) are a significant challenge in fluorescence spectroscopy, particularly at high optical densities.
• These effects distort fluorescence intensity, hindering accurate concentration measurements.
• Existing methods for IFE correction often require complex instrumentation or specific sample properties.

Purpose of the Study:

• To develop a robust method for correcting inner-filter effects in fluorescence measurements.
• To enable accurate quantitative analysis of samples with high optical densities using a compact flow system.
• To establish a generalizable strategy for fluorescence-based measurements in microfluidic and flow-based devices.

Main Methods:

• A novel two-point fluorescence detection flow cell was designed and fabricated.
• Empirical calibration methods were employed using fixed detection points within the flow cell.
• Fluorescence signals were measured under both static and dynamic (flow) sample conditions.

Main Results:

• The two-point detection strategy effectively corrected for inner-filter effects across a range of high optical densities.
• Linear fluorescence-concentration relationships were successfully restored, demonstrating improved accuracy.
• The method proved effective under both static and flow conditions, validating its general applicability.

Conclusions:

• The presented two-point fluorescence detection flow cell offers a practical solution for overcoming inner-filter effects.
• This approach enables reliable quantitative fluorescence measurements in compact flow systems, even at high optical densities.
• The empirical calibration strategy provides a versatile tool for various fluorescence-based analytical applications.