▎ 摘　　要

NOVELTY - Ratio fluorescence analysis for detecting sodium nitrite involves adding anhydrous citric acid to a beaker, heating and maintaining warm, observing that the citric acid turns into a light yellow liquid, dripping sodium hydroxide while vigorously stirring, neutralizing the solution with sodium hydroxide to obtain a graphene quantum dot aqueous solution, storing the solution in a refrigerator away from light, and diluting, establishing a standard curve, calculating a fluorescence intensity ratio (I578/I450), drawing a standard curve with the concentration of sodium nitrite as an abscissa and the fluorescence intensity ratio as an ordinate, determining nitrite in samples by replacing the standard solution of sodium nitrite with the equal volume of the processed sample, operating according to the establishment of standard curve, and substituting the measured fluorescence intensity ratio into the standard curve to obtain the concentration of sodium nitrite in the sample. USE - Ratio fluorescence analysis for detecting sodium nitrite in sample such as environmental sample, food sample, and industrial and physiological systems. ADVANTAGE - The method uses graphene quantum dot only needing one-step water-soluble method to synthesize, and is simple with high sensitivity (low detection limit of 12.9 ng/kg) and fast and convenient (reaction time) operations and has wide application prospect. DETAILED DESCRIPTION - Ratio fluorescence analysis for detecting sodium nitrite involves adding anhydrous citric acid to a beaker, heating to a certain temperature and maintaining warm for a period of time, observing that the citric acid turns into a light yellow liquid, taking it out, dripping sodium hydroxide while vigorously stirring, finally neutralizing the solution with sodium hydroxide to obtain a graphene quantum dot aqueous solution, storing the solution in a refrigerator away from light, and diluting by a certain multiple when using, establishing a standard curve by using a certain concentration of hydrochloric acid to prepare different concentrations of sodium nitrite standard solution and o-phenylenediamine solution, mixing the same volume to make it fully react for a period of time, using a saturated sodium hydroxide solution to adjust the pH to alkaline, adding the graphene quantum dots, measuring and recording the fluorescence emission spectrum in a range of 380-680 nm under excitation at 350 nm, calculating a fluorescence intensity ratio (I578/I450), drawing a standard curve with the concentration of sodium nitrite as an abscissa and the fluorescence intensity ratio as an ordinate, determining nitrite in samples by replacing the standard solution of sodium nitrite with the equal volume of the processed sample, operating according to the establishment of standard curve, and substituting the measured fluorescence intensity ratio into the standard curve to obtain the concentration of sodium nitrite in the sample.