title: Property evaluations and application for separation of small molecules of a nanodiamond-polymer composite monolithic column.
abstract: A nanodiamond-polymer composite monolithic column was first prepared successfully with modified nanodiamond (ND) as monomer, ethylene glycol dimethacrylate (EDMA) as cross-linker, 1-dodecanol as porogenic agent and benzoyl peroxide/dimethylacetamide (BPO/DMA) as initiator at 35°C for 2.5h. There was a sharp increase of specific surface area with ND added about 22 times from 0mg (3.90m(2)/g) to 7mg (81.2m(2)/g) determined with BET. Characterizations including scanning electron microscopy (SEM), fourier-transform infrared spectra (FIRT) and mercury intrusion porosimetry (MIP) were used to determine the microstructure, group composition, pore size distribution (≃1.56μm) and porosity (≃0.7484μm) of the monolith. An excellent column stability was confirmed by permeability (1.258x10(-10)cm(2)) and good linearity (R(2)=0.998) corresponding to backpressures measured at different flow rates. The highest swelling ability of the composite was about (5%) and classical RPLC of the column obtained occurred with the acetonitrile concentration increasing from 20% to 85% in the mobile phase, above which another retention model of normal-phase chromatography appeared. The items of the eddy dispersion and the absorption-release kinetics were the decisional factors of the composite column compared with the factors of longitudinal diffusion, and the skeleton-eluent mass transfer resistance due to the finite diffusivity. Good separation of neutral and basic small molecules was obtained (24,350 plates/m for neutral molecules and 22,300 plates/m for basic ones) with the hydrophobicity retention mechanism, but not for the acidic ones except to regulate the pH of the mobile phase.
authors.affiliation: College of Pharmacy, Hebei University, Baoding 071002, PR China; Hebei Province Key Laboratory of Pharmaceutical Quality Control, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding 071002, PR China.
authors.forename: Fengqing
authors.initials: F
authors.lastname: Wang
authors.affiliation: College of Pharmacy, Hebei University, Baoding 071002, PR China; Hebei Province Key Laboratory of Pharmaceutical Quality Control, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding 071002, PR China.
authors.forename: Aile
authors.initials: A
authors.lastname: Wei
authors.affiliation: College of Pharmacy, Hebei University, Baoding 071002, PR China; Hebei Province Key Laboratory of Pharmaceutical Quality Control, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding 071002, PR China.
authors.forename: Xixi
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Pharmacy, Hebei University, Baoding 071002, PR China; Hebei Province Key Laboratory of Pharmaceutical Quality Control, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding 071002, PR China. Electronic address: lhy1610@126.com.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Liu
authors.affiliation: College of Pharmacy, Hebei University, Baoding 071002, PR China. Electronic address: bailigai@163.com.
authors.forename: Ligai
authors.initials: L
authors.lastname: Bai
authors.affiliation: College of Pharmacy, Hebei University, Baoding 071002, PR China; Hebei Province Key Laboratory of Pharmaceutical Quality Control, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Hebei University, Baoding 071002, PR China. Electronic address: yanhongyuan@126.com.
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Yan
keywords: Composite; Monolithic column; Nanodiamond; Small molecules