| Pesticides are one kind of the important environmental pollutants.There are more than30kinds of organphosphorus pesticides （OPPs） and theyare extensively used in agriculture and industry. They can enter the humanand animal body according to the enrichment of food-chain and affect themetabolism of hormone in body. Because they are high effective and haverelatively low persistence in environment, they were still used in thelast years. Herbicides have been widely applied in agriculture to controlthe growth of weeds. Although the use of them has brought great benefitsfor crops, it also results in the potential harm to the environment becauseof the excessive and incorrect use of the pesticides. Usually, herbicidesare stable, they can remain in the crops after used. Through food-chainthey can enter the human body and endanger human health.In order to insurethe food safety, some countries had made very strict restriction onpesticide residues.Application of pneumatic nebulization （PN） for extraction of somepesticides in water and liquor was studied in this thesis. The concentricpneumatic nebulizer, which was used in the research, has advantages ofsimple structure, high efficiency of nebulization, stability and easyoperation. PN was combined with single drop microextractin （SDME） andgas-solid extraction （GSE） respectively. Two new extraction methods weredeveloped and applied to the extraction of pesticides in water and liquor,respectively.The pneumatic nebulization single-drop microextraction （PN-SDME） wasdeveloped and applied to the extraction and concentration of the OPPs, including dichlorvos, diazinon, malathion, phenamiphos and chlorpyrifos,in water samples. The samples was introduced and nebulized with thepneumatic nebulizer. The sample aerosol was passed though the spraychamber and condensed tube and arrived to the suspended drop. The dropwould be introduced into gas chromatograph-mass spectrometer （GC-MS）after analytes was extracted in the drop. Some parameters, such as thenitrogen flow rate, the type and volume of the suspended solvent and theextraction time, which can affect the performance of PN-SDME, wereoptimized. The nitrogen was used as carrier gas and the flow rate wascontrolled at900mL min-1.2.0μL of n-pentadecane was used as thesuspended drop solvent, the extraction time was20min and1.0μL of thesuspended solvent was then injected into the GC–MS system. The limitsof detection for dichlorvos, diazinon, malathion, phenamiphos andchlorpyrifos are0.0019μg mL-1，0.0014μg mL-1，0.0016μg mL-1，0.0015μgmL-1and0.0016μg mL-1, respectively. The linear range was0.0050to0.50μg mL-1, except for dichlorvos (0.0070to0.50μg mL-1). The recoveriesof the analytes in the spiked water samples were from75.2to105.3%.The relative standard deviations （RSDs） were lower than12.7%. The resultsshould be satisfactory. The volatile and non-volatile analytes can beextracted by PN-SDME and the suspended microdrop is very stable. Theintroduction and change of the samples was very convenient.The pneumatic nebulization gas-solid extraction （PN-GSE） was developedand applied to the extraction and concentration of the herbicides,including fenuron, chlortoluron, karmex, linuron and prebane, in liquorsamples. The samples was introduced and nebulized with the pneumaticnebulizer and then passed though the heating spray chamberand and theanalytes was extracted by solid phase extraction column. After theextraction was finished the column was taken out and eluted with acetone.The eluate was dried by nitrogen steam. The residue was dissolved in acetonitrile and the solution was then directly injected into the HPLCsystem. We selected250mg of aluminum oxide as the packed material,120℃as the temperature of spray chamber, the nitrogen as carrier gas and0.32Lmin-1as flow rate,4.2L min-1as the puming rate of gas and0.6mL ofacetone as the elution solvent. The eluate was be introduced inhigh-performance liquid chromatograph. The limits of detection forfenuron, chlortoluron, karmex, linuron and prebane are0.22μg L-1，0.25μg L-1，0.26μg L-1，0.23μg L-1and0.19μg L-1, respectively, and therecoveries of the analytes are96.0-103.1%（RSD≤5.1%），95.2-104.3%（RSD≤5.2%），93.5-102.1%（RSD≤6.5%），94.4-104.7%（RSD≤5.4%）å'Œ91.0-106.3%（RSD≤5.8%），respectively.The results should be satisfactory.The sample （for example, liquor）didn’t need to be diluted with waterbefore solid phase extraction when the content of organic substance wasvery high. So the proposed method has the good prospects of application. |
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