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Fluorescence spectroscopy is frequently used to analyze the concentration of fluorescent materials in solution. However, in conventional fluorescence spectroscopy, the response between the fluorescence intensity and fluorophore concentration is nonlinear at high concentrations due to uncompensated inner-filter effects (IFE). Many methods to resolve this problem have been developed in recent decades. This review introduces the methods used to correct the IFE, including direct correction and parameter correction. Relevant detection parameters, including the materials, matrices, detection limits, detection instruments and relative standard deviations, are tabulated. The advantages and limitations of these correction techniques are also discussed. Finally, the methods used to correct for the IFE are summarized, and future research directions are discussed. [ABSTRACT FROM AUTHOR]

A significant disadvantage of fluorometry is the inner filter effect when the fluorophore concentration is high. A new simple fiber-optic probe was made to measure the concentration of fluorescent solutions. The proposed probe consists of one excitation fiber and two emission fibers. One emission fiber is parallel to the excitation fiber, and the other has a tilted angle with the excitation fiber. A numerical model was used to optimize the tilted angle and distance of the three fibers. There was a linear relationship between the fluorophore concentration and the ratio of the fluorescence intensity of the two emission fibers. Using our homemade probe, we measured Eosin Y, fluorescein and quinine sulfate solutions. The linear range of Eosin Y solution was up to 500 μM, which was approximately 7 times the range measured with a single emission probe. The results of fluorescein and quinine sulfate solutions also showed that the fluorescence intensity ratio method could correct the inner filter effect. The experimental results also indicated that the probe is robust when the excitation light fluctuates. [ABSTRACT FROM AUTHOR]