1. Principle of Fluorescence Measurement
When a substance is irradiated with incident light of a certain wavelength (typically ultraviolet or X-ray), it absorbs the light and enters an excited state. The substance then emits light of a longer wavelength than the incident light (usually in the visible spectrum), which is called fluorescence. The generation of fluorescence occurs when molecules in the ground state absorb excitation light and transition to an excited state. These excited state molecules are unstable and, as they return to the ground state, release some of their energy in the form of light, thus producing fluorescence.
Different substances have distinct distributions of excitation energy levels due to differences in their molecular structures. These characteristics are reflected in their unique fluorescence excitation and emission spectra, allowing for qualitative identification of substances based on these spectra. In solutions, the fluorescence intensity of a fluorescent substance is usually proportional to its concentration, denoted by the formula IF = KC, enabling quantitative analysis of the fluorescent substance.
When measuring fluorescence in a sample, the sample cell is designed with slots specifically for placing fluorescence filters, which can be replaced as needed. Depending on the substance being measured, customers can select the excitation light source and fluorescence filters, using either lasers, specialized fluorescence LED light sources, or mercury lamps. Typically, filters with an optical density (OD) of up to OD3 are sufficient for most needs.
Figure 1. Schematic Diagram of Fluorescence Measurement Using a Sample Cell
For substances that emit fluorescence directly, their fluorescence intensity can be measured for quantitative analysis. Specific methods include:
1) Direct Comparison Method
Prepare standard solutions of known concentrations and measure their fluorescence intensities.
Perform appropriate pre-treatment or separation to remove interfering substances from the sample, then measure its fluorescence intensity.
Compare the fluorescence intensity of the sample with that of the standard solutions to calculate the concentration of the fluorescent substance in the sample.
2) Standard Curve Method
Measure the fluorescence intensities of a series of standard solutions of known concentrations.
Plot a standard curve with fluorescence intensity on the y-axis and fluorescent substance concentration on the x-axis.
Measure the fluorescence intensity of the sample and determine the concentration of the fluorescent substance from the standard curve.
2. Introduction to the Application System
1) Light Source
A stable power output and continuous spectrum radiation source, capable of emitting in the 200-400nm ultraviolet region and the 400-850nm visible region.
2) Sample Cell
Used to hold the sample to be tested, commonly using a quartz cuvette with a typical thickness of 10mm, and optional fluorescence filters.
3) Detection Equipment
Integrates optical dispersing components and detectors capable of photoelectric conversion. The SR50C fiber optic spectrometer from Jinsp is recommended for this measurement application.
4) Display
Connects the spectrometer to a laptop to display data during measurement, utilizing Jinsp's proprietary software.
Figure 2. Application System Diagram for Fluorescence Measurement
3. Product Recommendation
Fluorescence measurements typically use instruments like fluorescence spectrometers or fluorometers. The Jinsp SR50C fiber optic spectrometer can be used with a laser to adjust the excitation and detection wavelengths and measure the intensity of fluorescence signals and other characteristic parameters. The SR50C spectrometer is equipped with a high-resolution grating, detector, and data processing system, providing high-precision fluorescence spectrum data. For more details, please visit Best SR50C miniature spectrometer manufacturers and suppliers | JINSP (jinsptech.com)
4. Product Advantages
Compact size, lightweight, high resolution.
High sensitivity, suitable for trace element analysis.
High measurement accuracy and consistency.
Post time: Jul-11-2024