Research On The Development And Application Of Muliplexing Ion Mobility Spectrometry

Ambient pressure drift tube ion mobility spectrometry(IMS)is a an emerging analytical method to distinguish and quantitatively analyze different compounds by the different flight rates of gaseous ions in linear electric field.Ion mobility spectrometer has been recognized as a high sensitivity and low-cost instrument,and especially suitable for rapid field analysis.In this paper,a cross correlation ion mobility spectrometer(CIMS)was built independently,it was applied to the detection and analysis of volatile organic compounds(VOCs)by ultra-violet photoionization source and the parameters of the the IMS were optimized.High performance liquid chromatography(HPLC)coupled with CIMS was used to determine five alkaloid standards including cytisine,sophoridine,sophocarpine,matrine and aloperine,and to quantitate these alkaloids in the seed,seed coat,root,stem and leaf of sophora alopecuroides L.The main experimental results are as following:1.In order to improve the performance of home built ion mobility spectrometry including sensitivity and resolution,especially considering the high temperature applications and comtamination resistant performance,304 stainless steel is determined as the raw materials for drift tube electrode rings,99%alumina oxide ceramic is chosen as the insulation spacer materials for the drift tube,and cross correlation ion mobility spectrometry as the data acquisition and spectra processing.In order to modulate the ion gate and recover ion motility spectra from multiplexed ion current signals,a home made Labview based program is developed to sequences generation and real time data processing.Ultraviolet ionization and electrospray ionization are both implemented as the ion sources for CIMS.The electric field homogeneity inside the drift tube is simulated and optimized using Simion.The Solidworks3D design software is used to model the parts required by the IMS drift tube.The optimized final design is prototyped and tested and ready for the evaluation.2.Detection and analysis of 1,4-Dioxane was carried out by using our custom built photoionization correlation ion mobility spectrometer.The operation parameters of the CIMS method were optimized for sensitivity and resolving power.The optimal parameters including drift tube voltage,ion gate linear chirp square wave frequency modulation range,drift gas velocity and drift tube temperature were 10 KV,0-10 k Hz,800 ml/min and 393.15k.The resolution of the 1,4-Dioxane is up to 96 and the detection limit is 0.025ng/m L under the optimized experimental conditions.This experiment provids a feasible basis for the selection of various parameters for the determination of VOCs by IMS.Compared with the traditional single pulse and signal averaging data acquisition methods,the developed CIMS method demostrated higher resolution and lower limit of detection for 1,4-Dioxane.UV-CIMS also exhibites fast response,high resolution and high sensitivity,and can be applied to the detection of volatile organic compounds in the environment.3.HPLC was combined with CIMS using electrospray ionization source as interface to analyze five alkaloid standards including cytisine,sophoridine,sophocarpine,matrine and aloperine.Two-dimensional spectra of investigated five alkaloid standards were obtained and their retention time in HPLC dimension and drift time in ion mobility spectrometry dimension were determined.The IMS instrument demonstrated with very high resolving power up to 105without sacrificing detection sensitivity.The drift time of cytisine,sophoridine,sophocarpine,matrine and aloperine determined are 25.15 ms,29.0 ms,28.5ms,28.72 ms and 27.1 ms,and the calculated reduced mobility K₀are 0.828?0.718?0.731?0.725?0.769 cm²V^-1s^-1,respectively.The retention time of HPLC for five alkaloid compounds are 7.08min,17.98min,23.13min,24.26min and 40.91min respectively.Besides alkaloid molecular ions,dimer ion peaks or tripolymer ion peaks of the five standards can be easily detected by ambient pressure drift tube IMS.The isomer of sophoridine,sophocarpine,matrine have similar drift time in IMS for their molecular ions,but their dimer and trimer ions can be baseline separated thus can be clearly distinguished.HPLC-IMS two-dimensional separation was used to analyze the alkaloid profiles of seed kernal,seed capsule,root,stem and leaf of sophora alopecuroides L,and 54,54,36,45,44 compounds were detected respectively.The peak capacity for two-dimensional separation was calculated up to 21947.The contents of alkaloids in different parts of sophora alopecuroides L were quantitatively analyzed by external standard method.Sophoridine,sophocarpine,matrine are distributed in seed capsule,root,stem and leaf of sophora alopecuroides L.The contents of sophoridine in five parts are as follows:seed kernel(4.8%)>seed capsule(4.68%)>stem(4.12%)>leaf(3.72)>(1.85%).The contents of sophoridine are:(3.17%)>seed capsule(1.79%)>root(1.44%)>leaf(0.53%)>stem(0.50%).The matrine content in five parts are as follows:seed(5.37%)>teast(2.16%)>leaf(0.22%)>root(0.15%)>stem(0.106%).In addition to the absence of the cytisine in leaf,the contents of the other four parts are the seed(4.94%)>stem(2.47%)>root(0.68%)>teast(0.67%).Cytisine is not detected in the leaf of sophora alopecuroides L.momordica momordica,and the contents of cytisine in other four parts are the seed(4.94%)>stem(2.47%)>root(0.68%)>teast(0.67%).HPLC-IMS has higher resolution,lower detection limit than HPLC or IMS alone in the analysis of complex samples.HPLC separation and IMS separation show good orthogonality for two-dimensional analysis.HPLC-IMS can be used for quantitative analysis alkaloids in complex samples and provide further information for extraction,separation and analysis of alkaloids in sophora alopecuroides L.