Synthesis,Evaluation And Application Of A Novel Stationary Phase Based On Mild Thiol-michael Addition Reaction

Objective:（1）To develop thiol-Michael addition reaction and prepare a novel stationary phase.（2）To evaluate the chromatographic characteristics of the synthesized stationary phase.（3）To study the nonlinear chromatographic behavior.Methods:（1）Thiol-Michael addition reaction was used for the synthesis of the novel stationary phase（M-PVS）,in which PVS was added as bonded phase into the thiol-modified silica.Elemental analysis and solid-state ¹³C/CP MAS NMR were carried out for the characterization of M-PVS stationary phase.（2）The chromatographic characteristics of M-PVS were evaluated with uracil,nitrobenzene,fluorene,anthracene,toluene,ethylbenzene,o-terphenyl,triphenylene,phenol,caffeine,benzylamine,saponins and flavonoids.（3）van Deemter,Giddings,Horvath and Lin and Knox models were used to fit the mass transfer kinetics based on the experimental data acquired from the separation of hydroxytyrosol on M-PVS,C₈TDE,C₁₈ME and C₁₈TDE columns.C₁₈TDE column with good mass transfer characteristic was used to study the adsorption isotherm based on single component isotherm model.Results:（1）Carbon content of mercaptopropyl silicon and the carbon content of M-PVS were 3.30%and 7.83%in elemental analysis,respectively.The surface bonded density of M-PVS were calculated to be1.7μmol/m²based on the increased carbon content.Additionally,there are obvious chemical shifts of benzene ring carbon,sulfone group adjacent carbon and alkyl carbon atoms in MAS NMR data.Furthermore,the characteristic absorption peaks of benzene ring and thioether were detected in FT-IR spectra.（2）M-PVS column could provide hydrophobic,π-π,ion-exchange and hydrophilic interaction,demonstrating different selectivity from traditional C₁₈and phenyl column.The reversed phase and hydrophilic mode were observed when low ratio and high ratio of organic modifier were adopted,respectively.（3）The mass transfer process was characterized by van Deemter equation.C₁₈TDE,ethanol and 0.2 m L/min were adopted as the separation material,organic modifier and flow rate,respectively.Based on the investigation of adsorption thermodynamics,the adsorption behavior of hydroxytyrosol was confirmed to Langmuir isotherm model under the optimized chromatographic conditions.Finally,the purification process of hydroxytyrosol（purity 98.01%,recovery 90.98%,sample loading 1.6%）was successfully developed.Conclusion:（1）Thiol-Michael addition reaction with the advantages of mildness,high selectivity and high conversion rate successfully developed to prepared the novel stationary phase,which has great potential for the synthesis of various stationary phases with different selectivity.（2）M-PVS with multifunctional bonded ligands provided hydrophobic,π–π,hydrogen bonding,ion-exchange,and hydrophilic interactions,providing more options for the development of analytical methods.（3）An optimization strategy based on nonlinear chromatography was successfully developed by combining mass transfer kinetics with adsorption thermodynamics,which was a potential method for the purification process development in pharmaceutical industry.