Novel Methods Based On Carbon Nanotubes For Pretreatment Of Food Samples And Their Application For Determination Of Triazine Herbicides

Since 1940 s,food shortages have become global issues with the rapid growth of human populations.In order to improve the quantities and qualities of agricultural products,agricultural chemicals,such as pesticides and herbicides,were widely used in the productions of agriculture,which induced the toxic threats of chemical residues in foods.Therefore,the determination of chemical residues in foods becomes a serious issue during the production and consumption of foods for ensuring the health and safety of consumers.In this thesis,two novel methods based on carbon nanotubes for the pretreatment of food samples were developed and applied to the extraction and determination of triazine herbicides in grain and vegetable oil by using ultrafast liquid chromatography(UFLC).1.Improved Qu ECh ERS method by using multi-walled carbon nanotubes in the cleanup stageBy employing multi-walled carbon nanotubes as the cleanup absorbents,the traditional Qu ECh ERS method was improved to remove the vegetable oil components in the extracts effectively.With the elimination of the noises in chromatograms induced by the co-existed vegetable oil in extracts,good analytical performance was obtained by using this simple and rapid extraction method.The limits of detection(LODs)and quantification(LOQs)for three herbicides,including Atraton,Simetryn,and Atrazine,are 5.03-6.62 μg kg-1 and 16.76-22.04 μg kg-1,respectively.The intra-and inter-day precision are 2.07-7.29% and 1.11-6.66%(n=5),respectively.The developed method was applied to the analyses of 4 kinds of real samples.The recoveries ranged from 94.45% to 104.97%,with the relative standard deviations(RSDs)of 1.00-7.41%.2.Water-soluble ionic liquid-based dispersive liquid-liquid microextraction coupled with multi-walled carbon nanotubes-based clean-upWater-soluble ionic liquid were employed in the dispersive liquid-liquid microextraction of triazine herbicides in vegetable oils,followed by the effective cleanup using multi-walled carbon nanotube as the adsorbents for the eliminations of residual vegetable oil contents in extracts.Under the optimal experimental conditions,the LODs and LOQs of target analytes obtained by UFLC for three herbicides(Atraton,Simetryn,and Atrazine)were 2-2.28 ng m L-1and 6.70-7.58 ng m L-1,with the intra-and inter-day precision ranges of 1.48-7.29 % and 1.07-7.25%(n=5),respectively.Results obtained by the analyses of 4 kinds of real vegetable oil samples showed that the recoveries and RSDs were ranged in 94-108.28% and the 1.16-6.93%,respectively.Moreover,the low consumptions of organic solvents during the extraction and cleanup procedures made the present method meet the requirements of green chemistry.