title: Evaluation of 2,3-epoxypropyl groups and functionalization yield in glycidyl methacrylate monoliths using gas chromatography.
abstract: Poly(glycidyl methacrylate-co-ethylene dimethacrylate) (poly(GMA-co-EDMA)) is most frequently used as parent monolith to obtain stationary phases with a variety of surface chemistries for liquid chromatography and capillary electrochromatography. Functionalization is performed by opening the accessible 2,3-epoxypropyl groups of the monolith with a suitable reagent. The number of 2,3-epoxypropyl groups which are accessible before and after the functionalization reaction, and the grafting yield, are important parameters, required both to optimize functionalization and to interpret the chromatographic performance of functionalized monoliths. In this work, a method capable of providing this information for parent and functionalized poly(GMA-co-EDMA) monoliths prepared both in silica capillaries and in other supports is proposed. First, sulfuric acid and lithium aluminium hydride (LiAlH4) are sequentially used to release the 2,3-epoxypropyl groups as glycerol, which is subsequently determined by GC. About 6.0mmol of 2,3-epoxypropyl groups per gram of monolith was found in this work for the parent monoliths prepared in silica capillaries using UV-initiation. The monoliths were also functionalized using ammonia (NH3), diethylamine (DEA) and epinephrine, and the amount of residual 2,3-epoxypropyl groups, and hence the functionalization yield, were established by also measuring the GC peak of glycerol. The amounts of 2,3-epoxypropyl groups and the derivatization yields were established with RSDs of 1.7 and 3.4%, respectively. The proposed method was also applied to the characterization of poly(GMA-co-EDMA) monoliths prepared in glass vials. Significant differences with respect to those prepared in 100μm I.D. silica capillaries were evidenced.
authors.affiliation: Department of Analytical Chemistry, University of Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. Electronic address: enrique.carrasco@uv.es.
authors.forename: Enrique Javier
authors.initials: EJ
authors.lastname: Carrasco-Correa
authors.affiliation: Department of Analytical Chemistry, University of Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Ramis-Ramos
authors.affiliation: Department of Analytical Chemistry, University of Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. Electronic address: jmherrer@uv.es.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Herrero-Martínez
mesh_terms: D053801:Capillary Electrochromatography; D002623:Chemistry Techniques, Analytical / Q000379:methods* / Q000592:standards; D002849:Chromatography, Gas; D004852:Epoxy Compounds / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry*; D008768:Methylmethacrylates; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D004852:Epoxy Compounds; D008689:Methacrylates; D008768:Methylmethacrylates; C020347:GMA-EDMA; D012822:Silicon Dioxide; C007870:glycidyl methacrylate
keywords: Determination of glycidyl groups; Evaluation of derivatization yield; GMA-based monolithic columns; Gas chromatography; Monolith functionalization; Reactive monoliths