| As a sample pretreatment technology,solid-phase extraction(SPE)has been widely used in the field of food and environmental testing due to its advantages of high enrichment efficiency,simple operation,easy automation,and easy coupling with chromatography-mass spectrometry.etc..In the process of use and development,solid phase extraction has been developed a variety of pretreatment methods,such as magnetic solid phase extraction,dispersive solid phase extraction,etc.,which make it be more widely used.In this paper,we used the pretreatment method of solid-phase extraction.Compling with chromatography-mass spectrometry,we investided the best extraction conditions and detection conditions.The corresponding detection method established by us realized the enrichment,separation and detection of the harmful substances in food and water.1.Determination of five pesticide residues in onions by SPE combined with gas chromatography-mass spectrometry(GC-MS)A method for simultaneous determination of chlorothalonil,pentachloronitrobenzene and three insecticides(bifenthrin,fenpropathrin and fenvalerate)in onion by SPE combined GC-MS was established.In the course of the experiment,the optimal SPE conditions were investided,the instrument conditions of GC-MS were optimized,and the detection limit and precision were also tested.The results showed that the average recoveries of the five pesticides all reached more than 70% with the concentration range of0.01～1.00 μg/m L.The relative standard deviations were 3.30%～14.6%.And the linear correlation coefficients were all greater than 0.996.The minimum detectable concentration was 0.002～0.006 μg/m L.And the quantitative concentration was 0.006～0.018 μg/m L.The actual sample has been spiked and determined with the spiked recovery rate reached over80%.2.Determination of four veterinary drug residues in animal food by SPE combined with liquid chromatography-mass spectrometry(HPLC-MS)A method for the determination of four veterinary drug residues(Clenbuterol,Terbutaline,Ractopamine and Salbutamol)in animal food by SPE combined with HPLC-MS was established.The conditions of SPE were investided by using the automatic solid phase extraction instrument.And the loading and elution velocity of the automatic solid phase extraction were optimized.At the same time,the instrument conditions of HPLC-MS were also optimized.The detection limit and precision of the method were tested.The results showed that the average recoveries of the four veterinary drug residues were over 78% with the range of 0.5～10.0 μg/L.The relative standard deviations(RSD)ranged from 1.2% to 10.1%.And the linear correlation coefficients were over 0.999.The minimum instrumental detection concentration and quantitative concentration of the four veterinary drug residues were 0.5 μg/L and 1.5 μg/L,respectively.The method was applied to the determination of four veterinary drug residues in 60 meat products of cooked donkey and 170 pork ham intestines.The detection rates of positive samples were 2.94% and 2.5%,respectively.3.Determination of five organophosphorus pesticides in water by SPE combined with GC-MSThe water samples were separated,purified and enriched by automatic solid phase extraction instrument.And the determination method of five organophosphorus pesticides in water was established by GC-MS.The five pesticides tested in this experiment are Malathion,Parathion,Dichlorvos,Methyl Parathion and Dimethoate,separately.The water sample was enriched and purified with HLB small column and then eluted with eluant(ethyl acetate: dichloromethane,1:1,V/V).Finally,the water sample was determined by GC-MS and quantified by external standard method.The results showed that the linear correlation coefficients of the five pesticides were greater than 0.995 with the concentration range of 0.05～2.0 μg/m L.The average spiked recoveries were over 90%.The relative standard deviations were between 1.6 and 2.7%.And the minimum detection concentrations of the five pesticides were 0.017～0.046 μg/m L.The quantitative concentration was 0.051～0.130 μg/m L.Above all,the as-established method can be used for automatic detection of organophosphorus pesticide residues in daily drinking water.4.Preparation of polyethylenimine-magnetic carboxymethyl cellulose composite and its adsorption performance for Methyl parathionAs a magnetic solid phase extraction adsorption material,polyethylenimine-magnetic carboxymethyl cellulose(PEI-MCMC)complex was synthesized and its structure was characterized and analyzed.The adsorption performance of the adsorbents on methyl parathion was tested in the experiment.The results showed that the adsorbents showed excellent adsorption efficiency on methyl parathion in n-hexane system at room temperature.After 30 min,the adsorption equilibrium achieved with the adsorption capacity reached 66.42 μg/g.Based on the magnetic adsorption material,a new SPE-GC-MS method for the determination of Methyl parathion was established by detecting apple samples.The results showed that the linear correlation coefficient was0.9992 with the concentration range of 0.05～2.0 μg/m L.The recoveries of the samples were over 80%.The relative standard deviation was 6.64%.The minimum detection concentration of the instrument was 0.0018 μg/m L and the quantitative concentration was0.004 μg/m L. |
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