Kinetic analysis of DAF-FM activation by NO: Toward calibration of a NO-sensitive fluorescent dye

► We investigated the kinetics of DAF-FM activation by NO in aerated solutions. ► Data suggest NO2 rather than N2O3 as the reactive NO oxidation intermediate. ► The slope of DAF-T signal is related to [NO] according to ddt[FI]=2αk1[NO]2[O2][DAF-FM]k[NO]+[DAF-FM]. ► For [DAF-FM] > > [NO] the slope is proportional to [NO]2 and independent of [DAF-FM]. ► Recommendations for the calibration of DAF fluorescence are provided.