6,7-Difluoro-1,4-dihydro-1-methyl-4-oxo-3-quinolinecarboxylic acid, a newly designed fluorescence enhancement-type derivatizing reagent for amino compounds

A novel fluorescence enhancement-type derivatizing reagent for amino compounds, 6,7-difluoro-1,4-dihydro-1-methyl-4-oxo-3-quinolinecarboxylic acid (FMQC), was developed. FMQC reacts with aliphatic primary amino compounds to afford strong fluorescent derivatives having high photo-and thermo-stabilities. The FMQC derivatives of amino compounds showed 12-159 times higher fluorescence quantum efficiencies than those of FMQC in aqueous and polar organic media. Additionally, the absorption and fluorescence emission wavelength of the derivatives are red-shifted from those of FMQC. These differences in the fluorescence properties between FMQC and the fluorescent derivative enabled the simple and highly sensitive determination of amino compounds without removing any excess unreacted FMQC by using a simple spectrofluorometer as well as HPLC.