title: Separations of substituted benzenes and polycyclic aromatic hydrocarbons using normal- and reverse-phase high performance liquid chromatography with UiO-66 as the stationary phase.
abstract: Metal-organic frameworks (MOFs) have great potential for applications in chromatography due to their highly tailorable porous structures and unique properties. In this work, the stable MOF UiO-66 was evaluated as both a normal-phase (NP-) and a reverse-phase (RP-) stationary phase in the high performance liquid chromatography (HPLC) to separate substituted benzenes (SBs) and polycyclic aromatic hydrocarbons (PAHs). It was found that the mobile phase composition has a significant effect on the HPLC separation. Baseline RP-HPLC separations of xylene isomers; naphthalene and anthracene; naphthalene and chrysene; and naphthalene, fluorene, and chrysene were achieved using MeOH/H2O ratios of 80:20, 75:25, 85:15, and 75:25, respectively, on the UiO-66 column. Similarly, baseline NP-HPLC separations of xylene isomers and ethylbenzene; ethylbenzene, styrene, o-xylene, and m-xylene; and several PAHs were also obtained on the UiO-66 column with different mobile phase compositions. The relative standard deviations (RSDs) of retention time, peak height, peak area, and half peak width for five replicate separations of the tested analytes were within the ranges 0.2-0.4%, 0.2-1.6%, 0.7-3.9%, 0.4-1.1%, respectively. We also evaluated other critical HPLC parameters, including injected sample mass, column temperature, and the thermodynamic characters of both the RP-HPLC and the NP-HPLC separation processes. It was confirmed that the separation of SBs on a UiO-66 column was an exothermic process, controlled by both enthalpy change (ΔH) and entropy change (ΔS). The reverse shape selectivity, size selectivity, stacking effect, and electrostatic force played vital roles in the separations of these analytes. To the best of our knowledge, this method is one of the very few examples of using MOFs as the stationary phase in both NP-HPLC and RP-HPLC. MOF-based stationary phases may thus be applied in the separations and analyses of SBs and PAHs in environmental samples.
authors.affiliation: Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, PR China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
authors.forename: Chao-Yan
authors.initials: CY
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
authors.forename: Zeng-Guang
authors.initials: ZG
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Bai
authors.affiliation: Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Xiayan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Hongliang
authors.initials: H
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China. Electronic address: zhouyy@craes.org.cn.
authors.forename: You-Ya
authors.initials: YY
authors.lastname: Zhou
authors.affiliation: Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Yabo
authors.initials: Y
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
authors.forename: Fa-Sheng
authors.initials: FS
authors.lastname: Li
authors.affiliation: Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, PR China. Electronic address: jrli@bjut.edu.cn.
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Li
mesh_terms: D001554:Benzene / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000295:instrumentation / Q000379:methods*; D007536:Isomerism; D064347:Microscopy, Electrochemical, Scanning; D053758:Nanoparticles / Q000648:ultrastructure; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification*; D016062:Porosity; D013696:Temperature
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D001554:Benzene
keywords: HPLC separation; Metal-organic frameworks (MOFs); Polycyclic aromatic hydrocarbons; Stationary phase; Substituted benzenes