设计合成了荧光探针N,N-二乙基氨基香豆素-3-肼基-2,4-二硝基苯肼(DC)。光谱滴定实验显示，H2PO-4与DC能够以1∶1的化学计量比形成配合物。进一步的实验发现，和相同含量的DC溶液相比，该配合物溶液的相对光致荧光强度显著增强，同时伴有紫外吸收光谱红移，溶液颜色由橙黄色迅速变为紫色。其它阴离子，如 F-、NO-3、Cl-、Br-、I- 等对DC 溶液的相对荧光强度及紫外吸收光谱没有影响。利用DC对H2PO-4 具有灵敏选择性的特征，可把N,N-二乙基氨基香豆素-3-肼基-2,4-二硝基苯肼作为荧光探针，借助于荧光光谱和紫外-可见吸收光谱两种手段，实现对H2PO-4 离子的快速识别。

By combining 7-diethylamino-2-oxo-2H-chromene-3-carbohydrazide with 2,4-dinitrophenylhydrazine into one molecule, fluorescent probe ［7-diethylamino-2-oxo-N′-2,4-dinitrophenylhydrazine-2H-chromene-3-carbohydrazide］(DC) was synthesized for dsetection of H2PO-4 in acetonitrile. Spectrophotometric titration indicated the formation of a 1∶1 complex of H2PO-4 with DC. With the fluorescence spectra, the apparent red shift of UV absorption and the changes for the solution color from orange yellow to purple were observed as binding DC with H2PO-4. The experiment showed that DC was highly selective for H2PO-4, much more than those anions such as F-，NO-3，Cl-，Br- and I-. By the exclusive selectivity of DC to H2PO-4, it was predicted that as a fluorescent probe, and by means of fluorescence and UV-Visible absorption spectrum, H2PO-4can be rapidly identified by a enhanced fluorescence from DC.