Determination of melamine in milk based on β-cyclodextrin modified carbon nanoparticles via host-guest recognition

Illegal addition of melamine (MEL) to milk has caused serious food safety accident. It is urgent to develop a highly sensitive method for detecting MEL in milk. β-Cyclodextrin with inner hydrophobic and outer hydrophilic cavities have been widely used in smart sensors design. In this study, an "ON-OFF-ON" sensor for MEL detection was constructed based on β-cyclodextrin modified carbon nanoparticles (β-CD-CNPs). The sensor is switched "OFF" when Fe³⁺ interacts with β-CD-CNPs and switched "ON" when MEL replaces Fe³⁺. Fluorescence recovery of β-CD-CNPs exhibits good linear correlations with MEL concentration ranging from 10.00 ng/mL ~ 180.00 ng/mL and 180.00 ~ 1000.00 ng/mL, the detection limit is 6.82 ng/mL. The sensor was applied to analysis melamine in milk samples with recovery between 94.80% ~ 102.05%, and RSD bellow 12.61%. The results show that this method can meet the requirements of real sample analysis.