Study On Simultaneous Determination Of Sulfonylurea Herbicide Residues By LC-MS/MS

This paper selected multiwalled carbon nanotubes (MWCNTs) as solid-phase extraction sorbent, studied SPE sample treatment and detection condition of liquid chromatography-tandem mass spectrometry (LC-MS/MS), developed an effective and rapid method for simultaneous determination of seven sulfonylurea herbicides,(including thifensulfuron-methyl, metsulfuron-methyl, sulfometuron-methyl, prosulfuron, pyrazosulfuron-ethyl, chlorimuron-ethyl and primisulfuron-methyl) in environmental samples using LC-MS/MS. Quanlitative analysis was used the retention time and ion-pair compound, and quantitative analysis was carried out using an external standard.Important factors influencing the extraction efficiency such as pH of the sample solution, flow rate of sample loading, the eluent and its volume were optimized. The analytes were separated on a Zorbax Eclipse Plus C18column (2.1X150mm,3.5-Micron; Agilent), injected with a volume of5μL, and separated at a flow rate of0.2mL min-1using a mobile phase of water containing0.1%formic acid (A) and acetonitrile (B) under the gradient elute program. The instrument was operated in the positive ion mode with MS-MS detection in multiple reaction monitoring (MRM) mode. As the results showed, good linearity was obtained for all analytes (r2>0.9905) over the range of0.05-5000ng L-1, and precisions (RSD) for nine replicate measurements of a standard mixture of200ng L-1were1.9-7.4%. The limits of detection and quantification were0.01-0.20ng L-1and0.05-1.00ng L-1, respectively. The established method was successfully applied to the real environmental samples. The mean recoveries for seven compounds in the water samples at three spiked concentration levels were in the range of81.5to110.5%with RSDs between0.3and7.0%, the recoveries for the herbicides in the soil were from73.6-111.7%with RSDs of2.9-12.7%.For comparative studies, the LC-MS/MS method was also developed using C18as SPE sorbent to analyze sulfonylurea herbicides in environmental samples. MWCNTs showed greater potential of pre-concentration and clean-up for sulfonylurea herbicides at trace level in complex environmental matrix, which indicated that it has more extensive application fields and development prospects than the conventional C18sorbent.