Rapid Detection of Aflatoxin B1 in Cornflour by LED Excited Fluorescence Spectrometry

KeyWord:aflatoxin B1(AFB1)  LED excitation fluorescence spectrometry  Hg2+  rapid detection

Abstract:

      Aflatoxin£¨AFT£© is a type of difuran ring toxins produced by some strains such as aspergillus flavus and aspergillus parasiticus£®There are about 20 kinds of its derivatives£¬of which aflatoxin B1£¨AFB1£©is the most widely distributed£¬most toxic£¬and most harmful£®Therefore£¬extremely strict regulations have been imposed on the levels of AFB1 in various foods worldwide£®At present£¬the existing detection methods for AFB1 require large-scale instruments or have poor reproducibility£¬and most of them are difficult to achieve rapid on-site detection to meet market needs£®Fluorescence analysis is a common quantitative analysis method£¬which is simple£¬fast£¬and sensitive£®A small portable fluorscence instrument can easily be fabricated by assembling small optical devices£¬such as light source and small optical detector£¬which has the potential for rapid on-site testing. In this work£¬a fluorescence spectral detection device was constructed with a LED lamp as the excitation light source and a small fiber-optic spectrometer as the detection equipment£®Based on the fluorescence enhancement effect of Hg2+ on AFB1£¬a rapid fluorescence spectrometric method was established for the quantitative analysis of AFB1£¬using a Lumina fluorescence spectrophotometer at an excitation wavelength of 370 nm and an fluorescence detection wavelength of 443.2 nm. The pH value£¬solvent ratio£¬reaction time and other conditions of the reaction between Hg2+ and AFB1 were optimized£®Meanwhile£¬the interference factors of this method were explored and the anti-interference ability of the method was evaluated. Under the optimized conditions£¬there is a linear relationship between the fluorescence emission intensity of the AFB1£­Hg2+ system and AFB1 concentration in the range of 3£­90 ¦Ìg/L£¬with a correlation coefficient£¨r2£© of 0.996 and a detection limit of 0.913 ¦Ìg/L£®The first step of this method is to extract the AFB1 in the sample by magnetic stirring method£¬then making the extract clarified by filtering it with glass fiber filter paper£¬and finally using the special AFB1 immunoaffinity column to refer to the instructions for the aspergillus flavus in the sample to be tested£®AFB1 was specifically enriched and eluted with methanol£¬and then Hg2+ was added to the eluate to test the fluorescence spectrum of the sample£®This method was used to detect AFB1 in two kinds of cornflours£®The spiked recoveries ranged from 84.1% to 107%£¬with RSDs of 1.1%£­7.1%£®This study provides a new rapid method with high sensitivity and precision for the rapid detection of AFB1. In the future£¬it is expected that the detection method equipment will be assembled into a rapid detection kit£¬and the method is expected to be applied to the field of rapid detection.