Pellicular Particles with Spherical Carbon Cores and Porous Nanodiamond/Polymer Shells for Reversed-Phase HPLC

Abstract

A new stationary phase for reversed-phase high performance liquid chromatography (RP HPLC) was created by coating spherical 3 μm carbon core particles in a layer-by-layer (LbL) fashion with poly(allylamine) (PAAm) and nanodiamond. Unfunctionalized core carbon particles were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and Raman spectroscopy. After LbL of PAAm and nanodiamond, which yields ca. 4 μm core-shell particles, the particles were simultaneously functionalized and cross-linked using a mixture of 1,2-epoxyoctadecane and 1,2,7,8-diepoxyoctane to obtain a mechanically stable C(18)/C(8) bonded outer layer. Core-shell particles were characterized by SEM, and their surface area, pore diameter, and volume were determined using the Brunauer-Emmett-Teller (BET) method. Short stainless steel columns (30 × 4.6 mm i.d.) were packed and the corresponding van Deemter plots obtained. The Supporting Information contains a MATLAB program used to fit the van Deemter data. The retentions of a suite of analytes were investigated on a conventional HPLC at various organic solvent compositions, pH values of mobile phases, including extreme pH values, and column temperatures. At 60 °C, a chromatogram of 2,6-diisopropylphenol showed 71,500 plates/m (N/m). Chromatograms obtained under acidic conditions (pH 2.7) of a mixture of acetaminophen, diazepam, and 2,6-diisopropylphenol and a mixture of phenol, 4-methylphenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol, and 1-tert-butyl-4-methylphenol are presented. Retention of amitriptyline, cholesterol, and diazinon at temperatures ranging from 35 to 80 °C and at pH 11.3 is reported. A series of five basic drugs was also separated at this pH. The stationary phase exhibits considerable hydrolytic stability at high pH (11.3) and even pH 13 over extended periods of time. An analysis run on a UHPLC with a "sandwich" injection appeared to reduce extra column band broadening and gave best efficiencies of 110,000-120,000 N/m.

Multi‐instrument characterization of poly(divinylbenzene) microspheres for use in liquid chromatography: as received, air oxidized, carbonized, and acid treated

“…Accordingly, they are often suitable for applications under harsh conditions. [1][2][3][4][5][6][7] They can be made from natural materials, such as wood or coal. [8][9][10][11] They can also be prepared by the pyrolysis of polymers, such as polyacrylonitrile.…”

“…[2,3,8,[11][12][13]15,16,[18][19][20][21] Some of us have studied the preparation and properties of carbon/polymer/nanodiamond core-shell particles for highperformance liquid chromatography (HPLC). [1,[4][5][6][7] These particles exhibit excellent pH and thermal stability. Of course, silica based materials are the workhorse of modern liquid chromatography.…”

“…In our previous papers, we reported core-shell particles for HPLC from carbon cores, an amine containing polymer, and nanodiamond. [1,4,7] These materials were functionalized with C18 chains to create a mixed-mode column (a reversed-phase material with anion exchange properties). This phase showed unique selectivity.…”

Chemical Separation on Silver Nanorods Surface Monitored by TOF-SIMS

“…This causes some inhomogeneity in separation zone leading to zone spreading. Some separation specific, nanotextured films, preparation methods have already been documented in the articles published by Linford research group [24][25][26][27]. In the next step various PDMS microfluidic channel designs based on hydrogel procedure preparation will be examined [28] followed by an integration of nanostructured functional films into miniaturized systems.…”

Theory and Practice of UHPLC and UHPLC–MS

“…The preparation and evaluation of coreeshell material possessing a carbon core and nanodiamonde polymer shell have been reported (Bobály et al, 2015;Wiest et al, 2011). These types of particles, however, show relatively low efficiencies and have not yet been extensively studied.…”