How to measure the strength of the liquid fluorescence reaction?

Answer 1

The intensity of the fluorescent reaction of the liquid can be measured by direct or indirect methods.

** 1. Direct measurement method **
1. ** Direct comparison method **
- First, prepare a standard solution and measure its fluorescence intensity as F_x. The concentration of the standard solution is known as C_s. If the fluorescence intensity of the blank solution can be adjusted to zero, the content of the fluorescent substance to be tested in the sample can be calculated according to the comparison of the fluorescence intensity of the standard solution and the sample solution. If the fluorescence intensity of the blank solution cannot be adjusted to zero, the fluorescence intensity of the blank solution must be deducted from the fluorescence intensity of the sample solution and the standard solution.
2. ** Standard curve method **
- After the standard substance with known content was treated in the same way as the sample, a series of standard solutions were prepared and their fluorescence intensity was determined. A standard curve was drawn with the fluorescent intensity versus the fluorescent substance content. Then, the fluorescence intensity of the sample solution was measured, and the content of the fluorescent substance to be measured in the sample was calculated from the standard curve. In order to ensure that the standard curves drawn each time were consistent, the instrument should be corrected with the same standard solution each time. If the solution was unstable under the illumination of the ultra-violet light, another stable standard solution with similar fluorescence peaks should be used for correction. For example, when determining the standard curve of B1, the solution of Quinine Sulphate could be used as the standard correction instrument.

** II. indirect measurement **
1. ** chemical conversion method **
- For substances that cannot emit fluorescence or have a low fluorescence quantum yield, and the fluorescence is weak and cannot be directly measured, it can be changed into fluorescent substances suitable for measurement through chemical reactions. For example, the reaction of metals and chelators produces fluorescent chelates, and organic compounds can be converted into fluorescent substances through reactions such as biochemical reactions, oxido-reduction, couples, and condensations.
2. ** fluorescence quenching method **(The document does not describe the specific operation of this method in liquid measurement in detail. It only mentions this method).
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