聚乙烯吡咯烷酮(PVP)具有荧光特性，加入一定量的Fe3+之后，由于Fe3+和PVP发生反应导致体系荧光强度降低。而当在PVP-Fe3+体系中加入少量F-后，F-与Fe3+反应生成[FeF6]3-络合物导致体系荧光强度有所恢复，根据这种特性建立了一种Off/On型荧光光度法检测氟的新方法。在优化的实验条件下，荧光恢复程度与氟离子浓度在1.5 ～30.0 μmol/L呈现良好的线性关系，检出限为0.6 μmol/L。应用该方法对鱼肉中氟离子含量测定，回收率在93.33%～100.00%。

Polyvinylpyrrolidone (PVP) owned the apparent fluorescence characteristics. In the presence of a small number of Fe3+, the interaction between Fe3+ and PVP could lead to an obvious decreasing of PVP fluorescence. However, when a small amount of F-was added in Fe3+-PVP system, the fluorescence intensity could partly been restored, which was ascribe to the formation of [FeF6]3- complexes. Thus, a new Off/On fluorescence spectrophotometry was established for the detection of fluoride. Under the optimized experimental conditions, the fluorescence recovery degree showed a good linear relationship with the fluorine ion concentration in the range of 1.5-30.0 μmol/L. A detection limit as low as 0.6 μmol/L was obtained. This method was applied to the detection of fluoride ion in fish meat with satisfactory results. The recovery rates were between 93.33% and 100%.