Research On Capillary Gas Chromatography Column Based On Modified Seven-membered Guar Ring

In gas chromatography,the key to the efficient separation of the sample to be tested is the selectivity of the stationary phase and the method of preparing the column.The cucurbiturils has a unique hydrophobic internal cavity and a plurality of carbonyl oxygen atoms surrounded by ports at both ends.It has unique molecular recognition ability and good thermal stability,and has good application potential as a stationary phase for gas chromatography.Therefore,the synthesized(?HO?₁Q[7]was used as the stationary phase.The PDMS/?HO?₁Q[7]column was prepared by sol-gel method.The stationary phase coating was characterized by scanning electron microscopy and thermogravimetric analysis.The Golay curve,column efficiency,polarity,influence of injection volume on the column,thermal stability and repeatability of the column,and the separation ability of different components of PDMS/?HO?₁Q[7]column were also investigated.Discuss the separation mechanism of the column.The main contents are as follows:1.Synthesis by ammonium persulfate oxidation(?HO?₁Q[7],separation by column chromatography(?HO?₁Q[7]and Q[7]mixture,The elution was carried out with an eluent of acetic acid dihydrazide formic acid?V/V/V=10:10:2?and the composition of the eluate was followed by silica gel thin layer chromatography.Separately collect the eluates of Q[7]and?HO?₁Q[7],spin dry,and dry under infrared light to obtain the target product.it was characterized by IR?nuclear magnetic resonance,and the yield is 13.6%.2.Prepared by sol-gel method?PDMS/?HO?₁Q[7]?column,the morphology of the stationary phase coating is uniform,compact and crack-free,and the thickness of the stationary phase coating is about 1um;the thermal stability of the coating Good,PDMS/?HO?₁Q[7]has a 7.15%sample loss at 300°C,and can be used as a stationary phase separation sample for gas chromatography.3.To investigate the basic performance of the PDMS/?HO?₁Q[7]column,the Golay curve shows that the optimal flow rate of naphthalene is about 16.3 cm/s,and the optimal flow rate of n-dodecane is about 18.5 cm/s.Up to 1700 theoretical plates per meter;fixed phase total polarity 715,average polarity 143,belonging to medium polarity stationary phase;PDMS/?HO?₁Q[7]column relative to commercial column SE-54 for substances The enrichment retention is stronger,and the chromatographic peak area is larger in the same injection volume;the PDMS/?HO?₁Q[7]column can be used up to 300°C,has good thermal stability,and meets chromatographic analysis requirements;The column repeatability is good,the intra-day repetitive RSD is less than 0.2%,the daytime repetitive RSD is less than 0.4%,and the repeatability RSD between differ column is less than 0.6%.4.Characterization of the separation performance of PDMS/?HO?₁Q[7]column:the column exhibits good separation ability for mixed polar paraffins,esters,alcohols,aldehydes and ketones;five kinds of low boiling point compounds,seven kinds of boiling point close mixtures,five kinds of isomer compounds,Grob reagent and 22kinds of mixtures can achieve better separation effect,especially for seven kinds of boiling point similar compounds,ten kinds of high boiling compounds,The separation selectivity of the isomer and Grobs reagent is superior to that of commercial columns SE-54 and OV-1701,presumably due to the special cavity structure and molecular recognition ability of the monohydroxy seven-membered melon ring and its oxygen-containing functional group,so that it is separated.Inclusion compound,hydrogen bonding force,etc.between compound and certain components;PDMS/?HO?₁Q[7]column has good separation selectivity for polycyclic aromatic hydrocarbons?PAHS?,benzene halides,plasticizers,petroleum pollutants BTEX and other environmental pollutants.It is applied to the actual sample testing of water,environmental pollutants and petroleum pollutants in real life.5.To investigate the molecular recognition and retention mechanism of PDMS/?HO?₁Q[7]column-fixed relative solute molecules,using PAHS and alcohol as probe molecules,PDMS/?HO?₁Q[7]column separation The ratio of?S/?H in the molecular process of the probe is gradually reduced.The retention of PAHS/?HO?₁Q[7]for PAHS and alcohol is controlled by both enthalpy change and entropy change.Commercial columns OV-1701 and SE-54 are also the same.PDMS/?HO?₁Q[7]The type of force between the solute molecule and the stationary phase during the separation process,including hydrogen bonding interaction force,dipole-dipole action,dispersive force action,?-?action,n-?force and inclusion force.