| Mycotoxin has extremely strong toxicity as a secondary metabolite of fungi which can pollute crops,plants and their by –products during harvest the crops,poor drying,packaging,storage and transportation process,threatening human health seriously.The most common mycotoxins are aflatoxin,ochratoxin,zeaarlenone,deoxynivalenol,fumonisins,patulin,and alternaria fungus,which have a "carcinogenic,teratogenic,mutagenic" effect on people or animals with serious harm.So for this reason,it must be the focus of mycotoxins to detect and closely monitor.It is usually used to combine the immunoassay technique with high performance liquid chromatography(HPLC)for the accurate determination of mycotoxins,which have high sensitivity,good reproducibility and high accuracy.The time of single sample analysis is within 1 h.The cost of this method is higher and the antibody is not easy to preserve.The pretreatment technology is becoming more and more miniaturization,economization and environment protection.The ionic liquid dispersive liquid-liquid micro extraction which is called IL-DLLME has good effect such as simple operation,fast detection speed and low cost.At the same time,IL-DLLME has less damage to the environment because the ionic liquids replaced the traditional highly toxic chloride.In recent years,IL-DLLME has little reports on the detection of mycotoxins in agricultural products and food.Therefore,it is of great practical significance to study the detection of mycotoxins in food by IL-DLLME.In this study,we focused on the research on the sensitive and accurate detection of key mycotoxins(aflatoxin and ochratoxin)in agricultural products and foodstuffs.The experiment researched the ultrasonic and vortex assisted extraction methods,using the low toxicity environment friendly ionic liquid as DLLME extractant,combined with high performance liquid chromatography to detect main mycotoxin in liquid food such as edible oil,fruit juice.This experiment select the hard texture,uniform solid particles for the experimental samples,then using temperature-control assisted IL-DLLME to detect the aflatoxin B1 and ochratoxin A in the grain at the same time.The dection ofochratoxin A was further developed by combining QuEChERS(quick,easy,cheap,effective,rugged and safe)with IL-DLLME in solid foods which have certain moisture content,soft texture and uneven size.The specific research contents and results are as follows:1.A method was developed for the determination of mycotoxins in liquid foods using ionic liquid dispersive liquid-liquid microextraction(IL-DLLME)sample preparation coupled with high performance liquid chromatography(HPLC)for the analysis.First of all,the aflatoxin B1 in non-polar liquid food(edible oil)and the ochratoxin A in polar liquid food(grape juice)was taken as the target.Then the factors influencing the extraction efficiency such as extractant type and extractant volume,dispersant type and dispersion volume,pH value of water,ionic strength,auxiliary method and extraction time were studied respectively.Under the optimized experimental conditions,the recoveries ranged from 86.54% to103.92% with an RSD below 2.86 to 5.13%.The detection limit is 0.03 μg/kg with the limit of quantitation is0.13 μg/kg.The enrichment ratio is 9.90 ~ 10.57.The results showed that there was no significant difference between the IL-DLLME and SN / T3868-2014 on recoveries and the actual sample determination results.The recoveries of ochratoxin A ranged from83.88% to105.32% with an RSD below 5.64 to 7.83%.The detection limit is 0.05 μg/kg with the limit of quantitation is 0.17 μg/kg.And the enrichment ratio is 8.92 ~ 9.95.The contents of OTA in actual sample does not exceed the EU limit.This method has good effect such as simple operation,fast detection speed and low cost.2.A method was developed for the simultaneous detection of aflatoxin B1 and Ochratoxin A in grain samples using temperature control assisted extraction and ionic liquid dispersive liquid-liquid micro extraction(IL-DLLME)sample preparation coupled with high performance liquid chromatography(HPLC)for the analysis.The factors affecting the extraction efficiency such as extractant type and volume,pH of water phase,dissolution temperature and ice bath time were studied.Under the optimized experimental conditions,the average recoveries of AFB1 in the method was84.94% ~ 94.98%,the lowest detection limit was 0.03 μg / kg,the lowest limit of quantification was 0.11 μg / kg,the enrichment factor was 4.47 ~ 5.64,the relative standard deviation was less than 7.53 %.The average recoveries of OTA were 92.65% ~111.49%,the lowest detection limit was 0.08μg / kg,the lowest limit of quantification was 0.15μg / kg,the enrichment factor was 5.01 ~ 5.64,the relative standard deviationwas less than 6.38%.The content of AFB1 and OTA in the actual sample detection were lower than the standard of national standard,and there was no significant difference between the results of immunoaffinity chromatography and high performance liquid chromatography.This method has good effect such as simple operation,fast detection speed and low cost.3.A fast method was developed for the determination of Ochratoxin A in raisin samples using the quick,easy,cheap,effective,rugged and safe(QuEChERS)and ionic liquid dispersive liquid-liquid micro extraction(IL-DLLME)sample preparation coupled with high performance liquid chromatography(HPLC)for the analysis.The following parameters were systematically investigated: type and volume of cleaning age,extraction agent PH,type and volume of ionic liquid,salt addition,and vortex time.Under the optimized experimental conditions,good linearity was obtained with a correlation coefficient(r)of 0.9997 and a limit of detection(LOD)of 0.02μg/kg,a limit of quantification(LOQ)of 0.08μg/kg.The recoveries ranged from 86.29% to94.52%with an RSD below 5%.There was no significant difference in the detection of OTA content between the actual sample and the EU standard(immunoaffinity column chromatography).This method has good effect such as simple operation,fast detection speed and low cost. |
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