In this work, a cheap, simple, selective and sensitive turnoff fluorescent sensor was presented for Pb2+ determination. N-doped carbon dots (N-CDs) were synthesized by microwave-assisted method. Characterization of N-CDs was performed by transmission electron microscopy, dynamic light scattering and Fourier transform infrared spectroscopy. The important parameter (pH, concentration of carbon dots: CCDs and time) was optimized with Doehlert experimental design and response surface methodology. Optimum condition for maximum turnoff was pH 3, CCDs 8 mg mL−1 and 5 min. Limit of detection and linear range was 0.02 μM and 0.05–25 μM.
