Optimized preparation of nitrogen-doped carbon dots by response surface methodology and application in Cd2+ detection

The technical parameters of synthesizing N-doped carbon quantum dots (N-CQDs) from citric acid and tris(hydroxymethyl)aminomethane (Tris) were optimized using a Box-Behnken model of response surface methodology. Statistical analysis showed the quantum yield was significantly affected by reaction time and Tris weight. The optimal synthesis conditions were reaction temperature at 170 degrees C, reaction time of 4.50 h and Tris weight of 0.70 g, with the quantum yield up to 82.4%. The N-CQDs probe was further applied for Cd2+ detection. The fluorescence intensity and Cd2+ concentration were linearly related in the range of 20-300 mu g center dot L-1 with a relation coefficient of 0.9956 and a detection limit of 20.69 mu g center dot L-1.