Study On The High Efficiency And Low-cost Technology For Determining Aflatoxin B₁ In Grain And Edible Oil

By the research on the detection methods of aflatoxin B1(AFT B1) currently used, we developed an efficient and low-cost detection method of liquid chromatography(with a Post-column Derivatization System). After the research, we established the sample processing method of grain and edible oil, the instrument testing conditions and the precision evaluation of sample measurement. The results are as follows.The preparation steps of grain samples are as follows. Weighed 25.00 g crushed grain samples, put it to the homogeneous cup, add 100 mL methanol-water(7+3), high-speed homogenized 5min, stratified, weighed 5 mL supernate for high-speed centrifuging, then injected the sample and analyzed it.The preparation steps of edible oil samples are as follows. Weighed 5.0g edible oil samples, put them to the 25 mL graduated cylinder with stopper, add 20 mL Petroleum ether, shaking out it for dissolution, add 10 mL methanol-water(7+3), shaking out with stopper 5min, stratified, draw the substratum of methanol-water(7+3) extracting solution, quick frozen 10 min at-25℃, filter it quickly with 0.22μm filter membrane, then injected the sample and analyzed it.The detecting conditions of HPLC are as follows. The detection is fluorescence detector(FLD), the excitation wavelength is 360 nm, the emission wavelength is 440 nm, the mobile phase is methanol-acetonitrile-water(22 +22 +56), the flow rate is 1.0mL/min.The detecting conditions of Post-column Derivatization System are as follows. The chromatographic column is C18(4.6 × 250 mm × 5μm), the column temperature is 42℃, the reactor temperature is 90℃, the derivating agent is I2 solution(100mg/L), the flow rate is 0.3mL/min.The method is good for peak area response of AFT B1 standard sample. It is efficient for separating the AFT B1 standard sample in the grain and edible oil samples. The correlation coefficient of standard curve linear regression equation we built was 0.9993.the detection limits was 0.4μg/kg, Different concentrations of commercially available edible oil recovery was 90.4% to 99.4% and the relative standard deviation of 4.56%~5.36%, corn, rice and other grain at different concentrations recoveries are 91.2%~100.6%, the relative standard deviation is 1.40%~2.35%.The repeatability and accuracy of test results about AFT B1 in the grain and edible oil were better than existing methods, such as ELISA, immunoaffinity chromatography, fluorospectrophotometry.Compare with other methods, this method without any clean-up procedure by column, make detection simple, fast, low-cost, stable and reliable. The preparation steps were more simple and efficient, with higher sensitivity and accuracy, with lower detection limits. It is capable of detecting the AFT B1 in grain and edible oil.