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Aflatoxin (AFT) and ochratoxin (OT) is the most toxic mycotoxins two types of toxins, 1993 AFB1 by IARC (IARC) as a class of carcinogens, Ochratoxin Ochratoxin in A (OTA) are classified as Class II carcinogens. AFT and OT is not only highly toxic, but also pollute the very wide range, AFT hazards for food and feed there are many reports, the detection rate of 80% ~ 100%, OT were detected in a large number of contaminated food crops in many countries, more information showed that both AFT and OTA contamination often the same crops, and there is toxic additive effect, many countries and regions have developed AFT and OTA strict limits. At present, although the AFT and OTA were measured approach has been more mature, many scholars have done a lot of research, but its high cost were measured, and the measured time-consuming reagent serious loss, heavy workload. While the AFT and OT joint detection can be an effective solution to the above problem, shorten the analysis time, improve food security. Currently for food, agricultural products such as mycotoxins AFT and OT separate detection methods are mainly thin-layer chromatography, enzyme-linked immunosorbent assay, fluorescence spectrophotometry, colloidal gold immunochromatographic assay and HPLC, etc., but its reported less joint detection, although a small number of documents to establish their joint detection methods, but the method of the high cost of the equipment is expensive and can not promote the use of general laboratory a large area, which is restricted. Establish a low cost, easy to operate, fast, good purification effect AFT and OTA joint detection method, applied to detect mycotoxins in food crops, is of great significance. This study established the AFT and OTA in cereals combined detection methods, sample using ultrasonic extraction, purification of liquid-liquid extraction, HPLC - variable fluorescence wavelength detector. While the method accuracy, precision, sensitivity and linear range were studied, and with the current national standard method for comparison experiments, the main conclusions are as follows: (a) by fluorescence spectrophotometer at 200nm ~ 700nm range full band scan, AFT maximum excitation wavelength of about 360nm, the maximum emission wavelength of about 440nm; OTA maximum excitation wavelength of about 333nm, the maximum emission wavelength of about 477nm. After high performance liquid chromatography - fluorescence detector, AFT (derivatized) and OTA liquid chromatography on a strong fluorescent signal and each peak area of the fluorescence signal toxin and its corresponding concentration have a good linear relationship, Linear correlation coefficients were above 0.999, indicating by liquid chromatography - fluorescence detector detects AFT and OTA is feasible. (2) the extraction process, the various factors affect the extraction were studied. 5g sample volume is determined when the extraction recovery to meet the requirements of the recovery of more than 80%, variation coefficient of 10% or less; Different extraction methods for solid samples and OTA AFT great influence on the extraction rate, the ultrasonic treatment 20 ℃ 20min extraction can basically reach the maximum rate of recovery of about 90%, the detection processing time shorter than the national standard oscillation nearly 30min; experimental study of the concentration of the extraction agent, the extraction ratio of the extraction effect, 20mL80% methanol solution of 5g The extraction rate of the sample can reach maximum recovery rate of 80%; when the liquid-liquid extraction, the first extraction residual toxins still a small amount in the aqueous phase, extraction is not complete, the recovery is low, when the secondary extraction recovery was significantly higher extraction of toxins has been basically completely, so the experiment many times extraction is necessary. (3) in corn, rice, wheat, three samples spiked recovery was 71.73% ~ 115.37%, and the relative standard deviation was 3.00% ~ 9.88%; After seven consecutive day and intraday precision experiments, and the relative standard deviation 3.00% ~ 9.30%, three times the signal to noise ratio based on the peak responses to determine AFB1, AFB2, AFG1, AFG2 and OTA detection limits were 0.06,0.03,0.18,0.05,0.51 μg / kg, these five toxins respectively, at a concentration of 0.05 ~ 100.00,0.125 ~ 25.00,0.05 ~ 100.00,0.125 ~ 25.00,0.05 ~ 50.00μg / L range of linear correlation coefficient r = 0.9995,0.9996,0.9998,0.9992 and 0.9998; method validation results show, AFB1, AFB2, AFG1, AFG2 and OTA test results combined with the existing national standard testing methods alone showed no significant difference (P gt; 0.05).
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