Simultaneous Determination Of 24 Pesticide Residues In Water By SPE-LC-MS/MS

China is a big agricultural country,and it is also a big country in the production and use of pesticides.The large use of pesticides has increased the production of crops,but it has caused harm to the environment and the ecosystem.In our country,the utilization rate of pesticides is low,when pesticides are sprayed on fields,orchards etc,and most pesticides will remain in the environment and on the crops,then enter the nearby water with the way of precipitation,surface runoff,and soil leaching and so on.The residue of pesticides in the water make the water poor,a large number of fish die,even pose a threat to human health.Therefore,it is very important to detect and analyze pesticide residues in water.Amethodofsolid-phaseextractionandhighperformanceliquid chromatography-tandem mass spectrometry(SPE-HPLC-MS/MS)was developed to simultaneously determine 24 pesticides in water.Water samples were extracted with acetonitrile,then enriched and purified by solid-phase extraction cartridges.Acetonitrile and0.1%(v/v)formic acid aqueous solution were used as mobile phases.Target pesticides were analyzed by HPLC-MS/MS in positive electrospray ionization(ESI~+)conditions under multiple reaction monitoring(MRM)mode.Results showed that 24 pesticides were separated in 25 min with excellent linear relationship(R~2)≥0.998.The recoveries at spiking levels of 5ng/L,20 ng/L and 100 ng/L in water samples ranged from 65.9%to 127.8%with relative standard deviations(RSDs)of 0.7%~14.2%.The limits of detection were 0.05 ng/L~0.71ng/L.The proposed SPE-HPLC-MS/MS method is efficient,sensitive and reliable for the determination of various pesticides in actualwater samples.A total of 28 sampling points were chosen for the analysis of the target pesticides in the main sewage outfall,estuary and reservoir around Dalian by means of the established instrumental analysis method.The results showed that 19 pesticides were detected with the total concentration ranging from 4.18 ng/L to 6760.61 ng/L in each sampling points.The detection concentration of pesticides in reservoir water is low,and the number of detection is relatively small.The proposed SPE-HPLC-MS/MS method is efficient,sensitive and reliable for the determination of various pesticides in actual water samples.Acetochlor showed the highest detection rate of 100.00%with the detection concentration between 0.88 ng/L and13.51 ng/L,and halosulfuron-methyl showed the lowest detection rate of 3.57%,only one place has been detected.Prometryn had the highest detectable concentration of 6706.44 ng/L,and halosulfuron-methyl had the lowest detectable concentration of only 0.24 ng/L.According to the data of sampling points,it was found that the reservoirs were less affected by pesticides,and the main sources of pesticides in other estuaries and sewage outlets were from pesticide spraying in farmland and orchard,domestic sewage,industrial and agricultural wastewater.