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A new stationary phase for reversed-phase high performance liquid chromatography (RP HPLC) was created by coating spherical 3 mu m carbon core particles in a layer-by-layer (LbL) fashion with poly(allylamine) (PAAm) and nano-diamond. 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 mu m 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 x 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 degrees 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 degrees 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.

Item Type:	Refereed Article
Research Division:	Chemical Sciences
Research Group:	Analytical Chemistry
Research Field:	Separation Science
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Nesterenko, PN (Professor Pavel Nesterenko)
ID Code:	72704
Year Published:	2011
Funding Support:	Australian Research Council (DP110102046)
Web of Science® Times Cited:	39
Deposited By:	Chemistry
Deposited On:	2011-08-30
Last Modified:	2017-10-26
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