Study On Up-Conversion Fluorescent Sensor Method For Trace Citrinin

Citrinin (CIT), secondary metabolites produced by fungi, possesses carcinogenic, teratogenic and mutagenic potential hazards and often contaminated food grain, feed, etc.. At present, the commonly used methods for detection of CIT are based on high performance liquid chromatography, capillary electrophoresis and liquid chromatography mass spectrometry and so on. Although these methods are high sensitive, but often require complex pre-treated processes and expensive equipments. Therefore, the establishment of a simple, sensitive, low-cost detection method is very important.In this paper, a novel hexagonal up-conversion fluorescent nanomaterial based on molecular imprinting technology was prepared by using SiO2 coated hexagonal up-conversion material as carrier, the structural analogs of CIT 3,5-dihydroxy-2-naphthoic acid(DHNA) as the template molecule,3-amino-propionic-triethoxysilane as a functional monomer, tetraethoxysilane as cross-linking agent.The experiment parameters including the ratio of template, monomers and crosslinking agent, the amount of the carrier, the reaction temperature and time were optimized. The resultant material was characterized systematically, including fourier transform infrared spectra, adsorption equilibrium, adsorption kinetics, and so on. The quenching degree. of fluorescent molecule imprinted polymer increases with the concentration of CIT increasing and showed a good linear relationship with concentration ranging from 0.2 to 1.0 mg L-1. The limit of detection for CIT was obtain at 0.13 mg L-1.In order to evaluate the practicability of the developed method, standard spiked recovery experiments of blank samples were carried out at three concentration level (2.0, 4.0,8.0 mg kg-1 for red yeast rice,0.5,1.0,2.0 mg kg-1 for corn and 0.5,1.0,2.0 mg L-1 for rice vinegar), The recoveries were 82.0%-89.3%(RSD<5.0%),90.0%-98.0%(RSD<4.3%), 84.0%-94.5%(RSD<2.8%) respectively. In addition, high performance liquid chromatography (HPLC) was employed to further verify the validity of the fluorescent molecular imprinting method by standard spiked recovery at the same spiked concentration as the fluorescent molecular imprinting method. The recoveries were 69.0%-75.3%(RSD<8.6%) for red yeast rice,72.0%-83.0%(RSD<6.7%) for corn, 82.0%-85.5%(RSD<6.2%) for rice vinegar. These results demonstrated that the current method was promising for the accurate quantification of the CIT in foods.