| Aflatoxins and ochratoxins are two kinds of the most toxic mycotoxins. Aflatoxin B1 is served as carcinogen I by IARC and ochratoxin A is served as carcinogenⅡ. AFT and OTA are not only of strong toxicity, but also widely pollute the environment. AFT and OTA pollution in grain is often reported, and the detection rate is as high as 80%-100%. More data indicates that both AFT and OTA usually are the pollutants of the same food, and their toxin is of additive effect. Many developed countries and regions have set up strict limits for AFT and OTA. Although the respective detection of AFT and OTA have been relatively mature, the respective detection is time-consuming, expensive and laborious The simultaneous detection of AFT and the OTA is an effective solution to those problems. At the same time it can shorten the analysis time and improve food security. At present the main detection methods of AFT and OTA in grains are TLC, ELISA, GICA and HPLC, but the simultaneous detection of them are not widely reported. Although there are indeed some reports of simultaneous detection methods, they are of high cost and the equipments are rather expensive, which heavily limit their broad use in labs. To establish an economic, simple and fast simultaneous detection method of AFT and OTA in crops is of great significance.In this paper, a method was developed for the simultaneous detection of AFT and OTA in cereals, Cereal samples were extracted by ultrasonic and the extract was purified and concentrated, then was detected by HPLC-fluorescence detector. The conclusion was drawn by comparing the precision, accuracy, sensitivity and linearity range with that of the current national standard methods.(1) Every toxin's best wavelength was attained by scanning wavelength in a wide range of 200 nm～900 nm. The largest excitation wavelength of AFT was 360 nm; and the largest emission wavelength of was 440 nm; the largest excitation wavelength of OTA was 333 nm and the largest emission wavelength was 477 nm. AFT (after derivatives) and OTA show strong fluorescence signal on the chromatography, and each of their corresponding peaks had a good linear relationship with concentration. The linear correlation coefficient was above 0.999, indicating that the simultaneous detection of AFT and OTA was feasible by HPLC.(2) The various factors that affected the extraction efficiency were studied. When sample quantity was 5g, the recovery rate was above 80% and coefficient of variation was less than 10%; Different extraction methods would affect the extraction rate of AFT and OTA. Ultrasonic treatment (20℃and 20min) could basically meet the maximum extraction rate(about 90%), and the treatment time was 30 minutes shorter than the national standard method. The effect of extraction agent concentration and the extraction ratio were studied,80% methanol solution (20mL) and 5g samples could reach the largest extraction rate and the recovery rate was above 80%. When the liquid-liquid extraction was going on, the recovery rate is lower after the first extraction, but increased significantly after the second extraction. So the multiple extractions in the experiments were necessary.(3) Recoveries of the different cereal (corn, rice, wheat) with mycotoxins were 71.73% to 115.37% and the relative standard deviations were between 3.00% and 9.88%. The relative standard deviations of the precision experiments (7 times in a day and for 7 days) were 3.00%～9.30%. The detection limits were 0.06μg/kg for AFB1,0.03μg/kg for AFB2,0.18,ug/kg for AFG1 0.05μg/kg for AFG2 and0.51μg/kg for OTA. The linear detection range were 0.05～100μg/L for AFB1 0.125～25.00μg/L for AFB2,0.05～100μg/L for AFG1, 0.125～25.00μg/L for AFG2 and 0.05～50.00μg/L for OTA. The correlation coefficients were 0.9995 for AFB1,0.9996 for AFB2, 0.9998 for AFG1,0.9992 for AFG2 and 0.9998 for OTA. The tests showed that the simultaneous determination of the mycotoxins performed well, resulting in no significant difference compared with the current national standard methods (P>0.05).
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