Study On The Analysis Methods Of Aflatoxins And Fumonisins In Food

As it would blocking the immunoaffinity column in the process of cleanup when using the original method in determination the aflatoxin M1in milk and milk powder, the extraction method was optimized. In the study, acetonitrile and pure water were used to extract the aflatoxin M1in milk and milk powder. Then, the pellucid extraction was obtained, which can go through the immunoaffinity column by gravity. And using of large volume flow cell-fluorescence detection had risen approximately3times on sensitivity. Development of ultra-high-press liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with isotope dilution had increased the accuracy. The results showed that methods after optimizing with high sensitivity and accuracy, which can satisfy the minimum limit of aflatoxin M1in milk and milk products setted by GB2761-2011. Several derivation methods in determination of aflatoxins by UPLC were compared. In the comparison, a phenomenon was discovered, when using TFA pre-column derivation to detect aflatoxins, AFT B2a and AFT M2can’t be separated completely as some UPLC columns were used. Then, the method was optimized by changing the column and mobile phase, and the two substances were separated in baseline. As the result of comparison, UPLC-Large volume flow cell-fluorescence detector was selected, of which has increased the fluorescence intensity of AFTB1and AFT G1in detection, and avoided fussy operation in TFA pre-column derivation, and inhibited the phenomenon of peak diffusion in post-column derivation. It shows that this method had a high sensitivity, accuracy and recovery.Also, establish of UPLC-MS/MS to simultaneously detect four aflatoxins in food with four isotope dilutions had valid corrected the loss of analytes in the processing of pre-treatment and ionization. Also, it has avoided fussy operation in equipment of standers as without isotope it need equipment the standers with blank mixtures. With this method, the determination becomes much simple and accuracy. When determination of peanut paste samples,6aflatoxins were simultaneously detected in several positive samples, of which showed that microbe can also produce AFT M1and AFT M2.Otherwise, four pre-column derivations in determination of three fumonisins were compared, and the o-phthalaldehyde (OPA) was selected as the derivating agent in pre-column derivation. Then, the chromatographic conditions were optimized. Formic acid and ammonium formate aqueous were configured into buffer as mobile phase A, methanol was selected as mobile phase B. And the gradient elution was used in determination of FB1, FB2and FB3, of which improved the work efficiency and the sensitivity of FB1and FB2. Nevertheless, when using the phosphate buffer with methanol as mobile phase, it can’t use gradient elution as the mixed solution need vacuum filtration to remove the salts separated out in the process of mixture.In conclusion, the methods developed now were better than the original methods, of which were more suitable for determination of aflatoxins and fumonisins in food.