Covalent coupling fabrication of microporous organic network bonded capillary columns for gas chromatographic separation

Abstract

Microporous organic networks (MONs) have shown great promise in separation science recently. Exploring novel, simple and convenient strategy to fabricate MONs coated capillary columns for gas chromatography (GC) still remains challenging but desirable for the development of MONs in chromatographic separation. To extend the potential application of MONs in separation science and to further develop novel method for the fabrication of MONs-based capillary columns, here we demonstrate a novel covalent coupling strategy to fabricate uniform MONs bonded capillary columns for GC separation of position isomers and hydrocarbons. The bare capillary column was firstly modified with (3-bromopropyl)trimethoxysilane to provide bromine sites for coupling with alkynyl monomers. The amino- and hydroxyl-functionalized MONs (MON-NH2 and MON-OH) were then directly grown onto the inner wall of the brominated capillary columns via the covalent coupling between bromine and alkynyl groups. The uniform MON-NH2 and MON-OH bonded capillary columns were obtained and showed good resolution for GC separation of dichlorobenzene, chlorotoluene, bromotoluene, and propylbenzene position isomers and many other hydrocarbons including linear alkanes, alkylbenzenes, pinene isomers, cyclohexane and benzene, ketones and aldehydes. The MONs bonded capillary columns also owned good lifetime and precision for dichlorobenzene isomers with the relative standard deviations (RSDs) of 0.2–0.3%, 1.2–2.1%, and 1.7–2.5% for retention time, peak height and peak area, respectively. In addition, the fabricated MON-NH2 and MON-OH bonded capillary columns offered better resolution than commercial InertCap-1, InertCap-5, InertCap-1701 and InertCap-WAX capillary columns for the separation of chlorotoluene and bromotoluene position isomers. These results revealed the feasibility of covalent coupling strategy to fabricate MONs-based stationary phases in GC, highlighting the potential of MONs in separation science.