Determination Of Six Pesticides In Groundwater Using UPLC-MS/NS

This dissertation describes an analytical method involving a solid phase extraction(SPE)for the simultaneous ultra-performance liquid chromatography coupled with quadrupole tandem mass spectrometry(UPLC-MS/MS)determination of aldicarb,chlorpyrifos,dichlorvos,carbofuran,3-hydroxycarbofuran,and carbaryl in Miyun,Huairou and Shunyi county groundwater.Brief basic design of the study is as follows:(1)Chromatography was performed on ACQUITY UPLC?BEH C18(2.1 x 50mm,1.7?m)and Altus?UPLC?BEH C18(Column,130?,1.7?m,2.1 mm x 100 mm).ACQUITY UPLC?BEH C18(2.1 x 50mm,1.7?m)was found sufficiently good to be used for the whole experiments to detect groundwater samples.The mobile phase was water-methanol with 10mM ammonium acetate at flow rate of 0.2 ml min~-11 and the carbanilide(N,N'-Diphenylurea)was used as the surrogate standard.(2)The liquid chromatography separation and tandem mass spectrometry(MS/MS)optimization was studied to select the most appropriate operation conditions for all target pesticides.In order to achieve optimum performance,several extraction parameters such as required volume(mL),time(min),suck flow rate(mL/min),elution solvents and pressure to concentrate samples were all optimized.In the method,solid phase extraction was carried out using Oasis?HLB 6cc(500mg)LP extraction cartridge with acetone as elution solvent.In the linear range of each pesticide,the correlation coefficient was R~2?0.99.(3)Originally the method was developed for 10 pesticides;4 pesticides among them(aldicarb sulfoxide,aldicarb sulfone,methomyl and oxamyl)had poor responses in the method developed;they were not analyzed in the groundwater samples.The method was found satisfactory performance with limit of detection of 0.5-5ng/L,relative standard deviations of less than 10%and recoveries of 89-99%.The method was successfully applied to determine six pesticides in groundwater.The UPLC-MS/MS method developed is simple,rapid and suitable for the quantitation and confirmation of six carbamates in groundwater at levels lower than 5ng/L thus it is reliable for routine environmental analysis.