Fluorescence-based measurements for the determination of nitrite using a coumarin derivative sensor based on inner filter effect†
High-efficiency measurement of nitrite (NO2−) is of significant importance for both food safety and the management of health problems. In the present study, we established a fluorescent sensor for the selective detection of nitrite using 3-acetoacetyl-7-diethylaminocoumarin (ADC) and 3-aminophenol (3-Aph) based on a simplified Griess reaction and inner filter effect (IFE). Under strong acidic conditions, the rapid reaction between 3-Aph and nitrite formed an azoic compound (AZO) with the color changing from colorless to brown. The complementary spectral overlap between the absorption of AZO and the excitation of ADC induced IFE, leading to the fluorescence quenching of ADC. Under the selected optimal conditions, the proposed sensor exhibited a good linear relationship in the range from 0.1 μM to 50 μM (R2 = 0.9938) with the detection limit of 24.6 nM. Besides, the detection of nitrite in real pickle and bacon samples was successful and showed a maximum of 5% relative error with acceptable recoveries, demonstrating that this promising strategy can be employed for nitrite analysis in real-time applications.