Response surface methodology optimization for the synthesis of N, S-codoped carbon dots and its application for tetracyclines detection.

In this study, using a convenient one-pot microwave-assisted method, we rapidly fabricated a N, S-codoped fluorescent carbon dots (NSCDs) through using citric acid (CA) and d-penicillamine (DPA) for the detection of tetracyclines (TC). To rapidly and efficiently optimize the various synthesis parameters and significantly decrease the number of experimental runs, the effect of the synthesis factors on quantum yield (QY) by NSCDs was implemented through means of response surface methodology (RSM). The as-synthesized NSCDs presented superior photoluminescence stability with a strong quantum yield (QY) of 91.55% under optimal conditions, which was consistent with the predicted value using RSM. The fluorescence intensity of the NSCDs could be quenched effectively after adding TC by the inner filter effect (IEE) and photoinduced electron transfer (PET). Thus, the determination of TC by using NSCDs as a facile fluorescent probe was constructed in the range of 0.2-70 μM with a limit detection of 0.072 μM. Moreover, this detection approach has been utilized to detect TC in actual samples with satisfactory results.