Characterization and evaluation of magnesia-zirconia supports for normal-phase liquid chromatography

Zhang, Qinghe; Feng, Yu‐Qi; Da, Shi‐Lu

doi:10.1007/bf02497299

Cited by 34 publications

(29 citation statements)

References 31 publications

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“…30,31 Some of the physicochemical characteristics of the magnesia-zirconia composite are shown in Table 1. The data have been discussed in detail in another paper.…”

Section: Preparation Of Magnesia-zirconia Compositementioning

confidence: 99%

“…The data have been discussed in detail in another paper. 31 Preparation of alkylphosphonate 1-Dodecanol (100 mL) and sodium hydride (2.0 g) was stirred for 30 min at room temperature in an inert atmosphere of nitrogen gas. After 2.0 g of fosfomycin was added, the mixture was allowed to react at 120˚C for 48 h also in an inert atmosphere of nitrogen gas.…”

Section: Preparation Of Magnesia-zirconia Compositementioning

confidence: 99%

“…Nevertheless, the magnesia-zirconia composite exhibits appropriate surface area, pore size, pore size distribution and a better chromatographic performance. 31 In the present study, we report a new material of the porous A new material: magnesia-zirconia composite modified by an alkylphosphonate can be used as a reversed-phase stationary phase for high-performance liquid chromatography. The new material was characterized by elemental analysis, FTIR and 13 C solid state NMR spectrometry.…”

mentioning

confidence: 93%

“…28,29 Recently, we have prepared spherical silica-zirconia and magnesia-zirconia composites by the coprecipitation of zirconyl chloride with sodium metasilicate and magnesium chloride, respectively. 30,31 Those composites crystallized into tetragonal crystal structure after calcination at 600˚C, while the zirconia crystallized into monoclinic phase after calcination at the same temperature. These results suggest that not only silica but also magnesia are able to stabilize the tetragonal phase of zirconia.…”

mentioning

confidence: 95%

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Preparation and Characterization of Alkylphosphonate-Modified Magnesia-Zirconia Composite for Reversed-Phase Liquid Chromatography

Feng

Zhang

et al. 2000

ANAL. SCI.

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Since Nakamura and co-workers demonstrated zirconia as a packing material suitable for high-performance liquid chromatography (HPLC), 1-3 a great deal of attention has been paid to its application to HPLC. However, the applicability of this material is usually limited by the fact that there exist Bronsted acid sites, Bronsted basic sites and Lewis acid sites on the surface of zirconia, which can lead to irreversible adsorption of some compounds which should be separated. 4 Therefore, modification of this material is required to block such irreversible adsorption.Many efforts have been made to develop modified-zirconia packing materials for HPLC. Trudinger et al. 5 and Yu et al. 6 have tried to prepare chemically bonded zirconia with silanes for hydrophobic and hydrophilic stationary phases. However, Zr-O-Si bonds are quite unstable compared with Si-O-Si bonds. 5,7 Carr and co-workers have extensively studied carbon [8][9][10] and polymers 11-15 coatings on zirconia as surface modifiers of zirconia to create anion-exchange, hydrophobic and hydrophilictype phases with varying degrees of success. Since bare zirconia has a great affinity for Lewis bases, Carr and coworkers have studied modification of zirconia with Lewis bases such as fluoride, 16 phosphate 17 and ethylenediamine-N,N′-tetramethylphosphonic acid (EDTPA), 18 and their application in separation of proteins. We have studied preparation of spherical zirconia by sol-gel process 19 and modification of zirconia with stearic acid as reversed-phase for HPLC. 20 Nevertheless, low column efficiency was obtained due to low surface area and poor pore structure of the zirconia.Particle pore characteristics are crucial factors for chromatographic performance. 21,22 Nawrocki and co-workers have described the changes in surface area, pore size, and pore volume of zirconia with thermal treatment. 23 Carr and co-workers have compared the pore structures of zirconia synthesized with oil emulsion (OEM) and polymerization-induced colloidal aggregation (PICA) methods by means of nitrogen sorptometry, mercury porosimetry, size exclusion chromatography and NMR techniques. [24][25][26] They pointed out that nitrogen sorptometry and mercury porosimetry indicated a significant difference in pore volume and pore size distribution, and the presence of a considerable number of pore constrictions for the zirconia synthesized with the different methods. However, NMR results indicated that they have same average pore size and tortuosity. 25 Shalliker and Douglas have reported that the pore diameters, surface area and pore volumes of zirconia could be controlled by sodium chloride impregnation technique, and indicated that poor quality of pore structures was obtained without sodium chloride. 27 The crystalline phase of zirconia has also been shown to influence the surface area. Shalliker et al. have recently prepared spherical silica-zirconia composites by coating zirconia microspheres with silica. Their results illustrated that addition of the silica onto the zirconia microspheres ...

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“…30,31 Some of the physicochemical characteristics of the magnesia-zirconia composite are shown in Table 1. The data have been discussed in detail in another paper.…”

Section: Preparation Of Magnesia-zirconia Compositementioning

confidence: 99%

Section: Preparation Of Magnesia-zirconia Compositementioning

confidence: 99%

mentioning

confidence: 93%

mentioning

confidence: 95%

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Preparation and Characterization of Alkylphosphonate-Modified Magnesia-Zirconia Composite for Reversed-Phase Liquid Chromatography

Feng

Zhang

et al. 2000

ANAL. SCI.

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“…However, by introducing magnesia into zirconia, a more appropriate surface area, pore size distribution, and pore structure have been achieved in our laboratory [26]. These properties result in higher column efficiency in normal phase mode [27]. More importantly, the resultant mixed oxide, magnesia-zirconia (ZM), was found to have a greater affinity for phosphonates, and hence greater scope for development of its application in HPLC, than pure zirconia.…”

Section: Introductionmentioning

confidence: 96%

High‐performance liquid chromatography of some basic drugs on a n‐octadecylphosphonic acid modified magnesia‐zirconia stationary phase

Feng²,

et al. 2005

J of Separation Science

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The high-performance liquid chromatographic behavior of some basic drugs was studied on a n-octadecylphosphonic acid modified magnesia-zirconia (C18PZM) stationary phase. The effect of mobile phase variables such as methanol content, ionic strength, and pH on their chromatographic behavior was investigated. The retention mechanism of basic drugs on the stationary phase was elucidated. The results indicate that both hydrophobic and cation-exchange interactions contribute to solute retention under most chromatographic conditions. The inherent Brönsted-acid sites and also the adsorbed Lewis base anionic buffer constituents on accessible ZM surface Lewis acid sites play a role in the retention of ionized solutes by cation-exchange interaction. However, especially at high mobile phase pH, the retention of basic drugs depends mainly on hydrophobic interactions between solutes and support. Separations of the basic drugs on the C18PZM phase by a predominantly reversed-phase retention mode were very promising. The mixed-mode retention feature on this phase, as a result of the adsorbed Lewis base anionic buffer constituents acting as sites for cation-exchange, could also be very useful, e.g. for enhancing the chromatographic selectivity of such analytes. The C18PZM seems to be an excellent alternative to silica-based reversed-phase stationary phase for the separation of strongly basic solutes.

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Preparation and Characterization of Mg‐Zr Mixed Oxide Aerogels and Their Application as Aldol Condensation Catalysts

et al. 2012

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A series of Mg-Zr mixed oxides with different nominal Mg/(Mg+Zr) atomic ratios, namely 0, 0.1, 0.2, 0.4, 0.85, and 1, is prepared by alcogel methodology and fundamental insights into the phases obtained and resulting active sites are studied. Characterization is performed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N(2) adsorption-desorption isotherms, and thermal and chemical analysis. Cubic Mg(x)Zr(1-x)O(2-x) solid solution, which results from the dissolution of Mg(2+) cations within the cubic ZrO(2) structure, is the main phase detected for the solids with theoretical Mg/(Mg+Zr) atomic ratio ≤0.4. In contrast, the cubic periclase (c-MgO) phase derived from hydroxynitrates or hydroxy precursors predominates in the solid with Mg/(Mg+Zr)=0.85. c-MgO is also incipiently detected in samples with Mg/(Mg+Zr)=0.2 and 0.4, but in these solids the c-MgO phase mostly arises from the segregation of Mg atoms out of the alcogel-derived c-Mg(x)Zr(1-x)O(2-x) phase during the calcination process, and therefore the species c-MgO and c-Mg(x)Zr(1-x)O(2-x) are in close contact. Regarding the intrinsic activity in furfural-acetone aldol condensation in the aqueous phase, these Mg-O-Zr sites located at the interface between c-Mg(x)Zr(1-x)O(2-x) and segregated c-MgO display a much larger intrinsic activity than the other noninterface sites that are present in these catalysts: Mg-O-Mg sites on c-MgO and Mg-O-Zr sites on c-Mg(x)Zr(1-x)O(2-x). The very active Mg-O-Zr sites rapidly deactivate in the furfural-acetone condensation due to the leaching of active phases, deposition of heavy hydrocarbonaceous compounds, and hydration of the c-MgO phase. Nonetheless, these Mg-Zr materials with very high specific surface areas would be suitable solid catalysts for other relevant reactions catalyzed by strong basic sites in nonaqueous environments.

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Characterization and evaluation of magnesia-zirconia supports for normal-phase liquid chromatography

Cited by 34 publications

References 31 publications

Preparation and Characterization of Alkylphosphonate-Modified Magnesia-Zirconia Composite for Reversed-Phase Liquid Chromatography

Preparation and Characterization of Alkylphosphonate-Modified Magnesia-Zirconia Composite for Reversed-Phase Liquid Chromatography

High‐performance liquid chromatography of some basic drugs on a n‐octadecylphosphonic acid modified magnesia‐zirconia stationary phase

Preparation and Characterization of Mg‐Zr Mixed Oxide Aerogels and Their Application as Aldol Condensation Catalysts

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