Synthesis And Applied Research Of Two Organic Ester And Ether Grafted Polysiloxane Stationary Phases For Gas Chromatography

Gas chromatography technology is indispensable in the field of modern separation and analysis.It is widely used due to its fast analysis speed,high separation efficiency,high sensitivity,and easy automation.The chromatographic column is the main component of chromatographic instrument,and the choice of chromatographic stationary phase is often directly affects the analysis effect of the sample to be tested.With the increasing demand for the analysis of components with similar boiling points and similar structures in complex samples,especially food,medicine and environmental pollutants,the synthesis and research of various excellent gas chromatography stationary phases has become a hot topic for domestic and foreign chromatographic scholars.Polysiloxane is widely used in the field of gas chromatography stationary phase due to its advantages of high and low temperature resistance,weather resistance,aging resistance,physiological inertness,and good film-forming properties.In this project,ester groups and polyether segments are introduced into the main chain of polysiloxane,so that the stationary phase has both the easy film formation and temperature resistance characteristics of polysiloxane,and because of the grafting of selective groups,Increase the dipole-induced dipole and hydrogen bonding force between the stationary phase and the analyte,thereby improving the separation selectivity of the stationary phase to alcohols,esters,ethers and other mixtures.The main work of this paper includes the following aspects:(1)Synthesis of methyl hydrogen-containing silicone oil with different hydrogen content.High molecular weight methyl hydrosiloxane oil with hydrogen content of 13.8%and 21.6%was prepared by cationic ring-opening polymerization with octa-methylcyclotetrasiloxane(D4)and 1,3,5,7-tetramethylcyclotetrasiloxane(D4H)as raw materials and hexamethyldisiloxane(MM)as capping agent under the catalysis of trifluoromethyl sulfonic acid(TfOH).(2)Synthesis of ethyl undecanoate grafted polysiloxane(EUP).Through the hydrosilylation reaction,under the catalysis of chloroplatinic acid-isopropanol solution,ethyl undecylenate is grafted onto the long chain of methyl hydrogen-containing silicone oil to obtain ethyl undecanoate grafted polysiloxane stationary phase(EUP-20)with a grafting rate of 20%.(3)Synthesis of polyether grafted polysiloxane(AEPP).Using allyl polyoxyethylene ether(APEG-1000)as raw material,anhydrous tetrahydrofuran as solvent,under NaH alkaline conditions,nucleophilic substitution reaction occurs with 1-chlorobutane to obtain butyl-terminated allyl Base polyether;and then through the addition of hydrosilylation,the polyether segment is grafted to the long chain of methyl hydrogen-containing silicone oil,and the grafting rate is 10%and 18%respectively(AEPP-10 and AEPP-18).(4)Chromatographic column evaluation.The synthesized stationary phase was coated on the inner wall of a quartz capillary by a static method,and its column efficiency,temperature resistance,inertness and polarity were evaluated.The results show that the two ester and ether grafted polysiloxane stationary phases have good film-forming properties and temperature resistance,and the prepared chromatographic column has high column efficiency and good surface inertness.The McReynolds constant of EUP-20 column is 497,which is a low polar column;the McReynolds constant of AEPP-10 column is 972,and the McReynolds constant of AEPP-18 column is 1153,both of which are medium polarity columns.The solvation parameters(Abraham system constants)show that the main forces of EUP and AEPP columns are dipole-induced dipole force and hydrogen bond force.(5)Evaluation of separation performance of EUP-20 and AEPP chromatographic columns.Through the separation and analysis of the mixture of fatty acid esters,fatty alcohols and ethers prepared by the laboratory,both types of chromatographic columns show good separation results.In the actual sample separation,not only the trace components in the commercially available liquors were well separated,but also the flavors and fragrances and the cigarette smoke absorption liquid with complex components were also obtained good analysis results,indicating that EUP and AEPP two chromatographic columns are suitable for The qualitative and quantitative analysis of actual samples containing complex alcohol esters has great potential application value in the fields of food and environmental analysis.