Study On Simultaneous Determination Of Five Biopesticide By Lc-Ms/Ms

In this paper, an effective and rapid method for simultaneous determination of5biopesticides (including hyoscyamine、rotenone、nicotine、spinosad and matrine) in environmental samples using LC-MS/MS was developed. C18was selected as solid-phase extraction sorbent to study SPE sample treatment and detection condition of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Retention time and ion-pair compound was used for qualitative analysis, 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, as well as the concentration of ammonia water in eluent were optimized. The analytes were separated on a CAPCELL PAK C18MG II column (150mm×2.0mm,3μm), injected with a volume of1μL, and separated at a flow rate of0.2mL min-1using a mobile phase of water containing5mM ammonium acetate (pH was adjusted to4.0)(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>0.9923) over the range of0.154-50.0μg L-1. The limits of detection were0.002-0.020μg L-1and precisions (RSD) for nine replicate measurements of a standard mixture of0.1μg L-1were1.8-8.5%. The established method was successfully applied to the real environmental samples. The mean recoveries for5compounds in the water samples at three spiked concentration levels were in the range of60.7to112.7%with RSDs between2.4and10.7%, the recoveries for the herbicides in the soil were from67.6-110.5%with RSDs of1.9-9.4%.For comparative studies, the LC-MS/MS method was also developed using multiwalled carbon nanotubes (MWCNTs) as SPE sorbent to analyze5biopesticides in environmental samples. MWCNTs showed almost the same ability of pre-concentration and clean-up for5biopesticides at trace level in environmental matrix as the conventional C18sorbent.