| The raw material of Camellia oil is a China's unique evergreen shrub-Camellia.Which combined with oil palm,olive and coconut are four major woody oil crops in the world.Camellia oil enriched with bioactive ingredients,like unsaturated fatty acids,vitamins,camellia saponin and squalene,etc.It's a high-grade vegetable oil with high edibleness and medicinal value,which make it has a bright development and application future.In recent years,food safety incidents frequently happened.Camellia oil,one of the basic necessities of human life,so people are particularly worried about the raw material get contaminated with pesticides,PAHs,phthalates,heavy metals,etc.from surrounding environment during raw material cultivation,production,processing,transportation,storage process.Hunan is the largest Camellia plantations in our country.To protect the safety of Camellia oil consumption,reach the regulatory requirements around the world,set up the quality reputation of edible oil,we should pay more attention on the safety Camellia oil.Therefore,to establish a simple,common,accurate and reliable method for rapid detection of the harmful pollutants in Camellia oil is an extremely urgent task.Because of the large specific surface area,strong adsorption capacity etc.,nano-materials have been used more and more widely in food analysis area.This project mainly focus on the method development of the harmful pollutants detection in Camellia oil with the use of functional nano-materials combined with modern instrumental analysis techniques.The main results of this study are summarized as follows:1.A modified "QuEChERS,method had been established,instead of the conventional purification adsorbent with a mixture of multi-walled carbon nanotubes and neutral alumina,combined with gas chromatography-tandem mass spectrometry.This updated method have been used in 11 organophosphorus pesticide residues detection in Camellia oil.Furthermore,the type of extraction solvent,the type and amount of multi-walled carbon nanotubes,the type of fat adsorbent and adsorption purification time have been optimized.The results showed that extract the samples with acetonitrile,and the extraction solution was enriched and purifies for 5 min using 100 mg carboxylated multi-walled carbon nanotubes and neutral alumina sorbent mix in order to remove fat and other impurities from the Camellia oil that affect on the results of the measurement effectively.With this method,the detection of 11 organophosphorus pesticides in the range of 0.01?0.5?g/mL had a good linearity,the correlation coefficient was 0.99961-0.99996 the recovery of these 11 targets were 86.2%?112.6%when they were in the range of 0.02?0.1 mg/kg,with the RSD of 3.2%?11.2%.The quality control data met the national standards of pesticide residue testing requirements.2.In this study,a multi-walled carbon nanotubes self-made solid-phase extraction column has been used for Camellia oil pretreatment,combined with ultra performance liquid chromatography-tandem mass spectrometry has been used for rapid analysis of 12 carbamate pesticide residues in Camellia oil.Samples were extracted by ultrasonic treatment,the solid phase extraction column filled with 75 mg MWCNT-1(outer diameter of 10-20 nm,length 10-30?m),elution solvent was 8 mL acetonitrile.Compared with commercial Cis solid phase extraction column and self-made 70 g graphene oxide(GO)solid phase extraction column,multi-walled carbon nanotubes had a ideal purification effect for the 12 carbamate pesticide residues in Camellia oil,it could effectively eliminate matrix effects with stable recovery.It had a good linear correlation(the coefficients were all greater than 0.9988)when the 12 carbamate pesticides were in the range of 0.005?0.1?g/mL;the average recoveries these 12 objects was 78.3%?115.9%with the relative standard deviation of 2.6%?11.8%.3.Used synthetic magnetic graphene composites,and transmission electron microscopy,X-ray diffraction analyzer,Fourier transform infrared spectroscopy to characterize synthetic magnetic graphene composites.The characterized magnetic graphene composites have been used in Camellia oil sample pretreatment for phenoxy acid pesticide residue analysis.This have been successfully used for the rapid analysis of 5 phenoxy acid herbicides in Camellia oil by magnetic solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry.The use of magnetic graphene in the detection of phenoxy acid pesticides in Camellia oil relatively decressed the analysis time and cost,it also incressed the efficiency of adsorption and elution of the target compounds.The result showed a good linear correlation with the coefficients greater than 0.99968 when the 5 phenoxy acid pesticides within 0.01?0.2 mg/kg range;the average recovery rate was 88.1%?95.0%with the RSD of 2.6%?7.3%when these 5 targets on the levels of 0.02,0.05,0.1 mg/kg,which totally meet the testing needs of the 5 phenoxy acid pesticides in Camellia oil.4.This project also studied the detection method of 6 phthalate plasticizers in Camellia oil.Results showed that use SWCNTs as glass SPE adsorbent column in the enrichment and purification of PAEs in Camellia oil could effectively remove the interference of grease and other macromolecules,which combined with GC-MS is a powerful tool in our analysis.The optimized extraction conditions were:The volume of hexane for Camellia oil dulition was 5 mL,SWCNTs dosage was 0.6 g,eluent was 20 mL hexane,elution solvent was 5 mL toluene.The results has a good linear correlation when the 6 PAEs were in the range of 0.05?1.0 ?g/mL with the coefficients(r)greater than 0.9999;and the average recoveries of these 6 targets were 86.4%?111.7%with the relative standard deviation of 4.2%?10.4%.It was found that the purifying effect of the experimental used homemade SWCNTs glass SPE cartridges was not less than usual commercial PSA,C18SPE small column,and the SWCNTs SPE cartridge could be repeatedly used after washed by 5 mL toluene,which greatly reduced the cost of analysis.5.Established a rapid analysis method for 8 PAHs in Camellia oil with using of magnetic nanotubes solid phase extraction-gas chromatography-mass spectrometry.The magnetic MWCNTs prepared by hydrothermal synthesis have a better dispersion,adsorption capacity were characterized by transmission electron microscopy,X-ray diffraction analyzer,Fourier transform infrared spectroscopy.And then,successfully applied to the pre-treatment of the 8 PAHs detection in Camellia oil.Throught the adsorption and enrichment of the target in Camellia oil by magnetic carbon nanotubes and the desorption process in toluene solvent,polycyclic aromatic compounds were effectively separated from Camellia oil.The use of magnetic nanotubes in the detection of PAHs in Camellia oil was greatly reduced the pre-treatment time,reagents saving and reduced the laboratory personnel injury by organics durning test.The results had a good linearity with the correlation coefficients greater than 0.999 when these 8 PAHs were in the range of 0.01?0.2 mg/kg;the average recoveries of these 8 targets were 91.5%?97.2%with the RSD of 2.2%?6.2%when they were on the levels of 0.01,0.05,0.2 mg/kg,which completely able to meet the 8 PAHs testing needs in Camellia oil.6.Established a method to analysis heavy metals,copper,cadmium and lead in Camellia oil by hydroxylation of carbon nanotubes solid phase extraction-flame atomic absorption spectrometry.Optimized the type,length and use amount of the multi-walled carbon nanotube with homemade solid phase extraction column.The results showed use 200 mg hydroxylation short tube(MWCNT-3)as the adsorbent for self-made solid phase extraction column was the best condition.Based on the strong selective adsorption ability to copper,cadmium and lead,hydroxylation multi-walled carbon nanotubes solid phase extraction column could effectively enrich and separate copper,cadmium and lead from Camellia oil.And then flame atomic absorption spectrometer could be used to detect trace amounts of copper,cadmium and lead ions in Camellia oil with faster speed and lower cost compared with other analytical instruments.The result showed a good linear correlation with the coefficients greater than 0.999 when the copper ions and lead ions were in the range of 0.5?4.0 mg/kg;the average recovery of these three irons was 90.5%?94.0%with the RSD of 2.1%?3.8%within the linear range,which fully meet the copper,cadmium and lead ions testing needs in Camellia oil. |
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