Abstract: To explore a simple, rapid and sensitive method for the detection of doxycycline hydrochloride (DOX), metronidazole (MTZ) and sulfadimidine (SM2) in pork and milk, a porphyrinic zirconium metal-organic framework (MOF) material, PCN-225, was synthesized as a fluorescence probe and used to construct a fluorescence sensor to determine the concentrations of DOX, MTZ and SM2. First, the morphology, structure and properties of PCN-225 were characterized and optimized, and the sensing mechanism of PCN-225 was analyzed by fluorescence spectroscopy and ultraviolet-visible (UV-Vis) absorption spectroscopy. Second, the sensing performance of PCN-225 for detecting the three antibiotics was studied. The results showed that the developed method showed excellent selectivity and sensitivity for the detection of DOX, MTZ and SM2, with detection limits of 4.70, 5.30 and 4.84 nmol/L, respectively. Finally, the sensor was used to detect DOX, MTZ and SM2 in pork and milk. The recovery rates ranged from 94.7% to 110.8%, with relative standard deviations (RSDs) not higher than 1.1%. In conclusion, this method shows great potential for the detection of DOX, MTZ and SM2 in a simple, efficient, sensitive and rapid manner.

Key words: metal-organic framework; doxycycline hydrochloride; metronidazole; sulfadimidine; fluorescence detection