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1.
Crosslinked polysiloxane stationary phases were prepared on soda-lime glass capillaries and applied to the separation of polynuclear aromatic hydrocarbons and of phthalates in reversedphase liquid chromatography. Preparation procedures and chromatographic performance of these columns are described. 相似文献
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Summary Silica-bonded stationary phases were developed for the separation of nucleic acid constituents and their properties investigated
with homologous oligoriboadenylic acids in electrostatic interaction chromatography and with alkylbenzenes in reversed-phase
chromatography. Analysis of retention data confirmed the stratified molecular structure of the surface which consist of a
layer of propyl chains anchoredvia siloxane bridges to the silica surface proper and of polar moieties attached to the hydrocarbonaceous functions. The polar
top layer contains weak cationic and/or hydrophobic binding sites, is strongly hydrated in contact with aqueous eluents and
bars the access by large biopolymers to the hydrocarbonaceous sublayer. In reversed-phase chromatography of small non polar
molecules with hydro-organic eluents, however, this layer is accessible and engenders a retentive behavior typical for weak
hydro-carbonaceous bonded phases. As a result the stationary phases, depending on the nature of the sample and the mobile
phase, exhibit the properties of "soft" phases for the chromatography of biopolymers under mild elution conditions and those
of "hard" phases for the separation of small non-polar molecules under conditions generally employed in reversed-phase chromatography.
The retention of nucleic acid constituents on most of the stationary phases investigated subject to a dual mechanism as a
result of the interplay of electrostatic and hydrophobic interactions between the eluites and the binding sites on the stationary
phase surface. Siliceous stationary phases having surface morphology described above are suitable for the separation of nucleic
acid constituents having widely ranging molecular weights up to 3 × 106 Daltons provided the support has appropriate pore dimensions. This is demonstrated by the separation of mixtures arising
from digesting t-RNApha or polyadenylic acids as well as those of ribosomal RNA’s and different forms of the plasmid pBR322 DNA.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
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In this study, the retention and selectivity of a mixture of basic polar drugs were investigated in hydrophilic interaction chromatographic conditions (HILIC) using nano-liquid chromatography (nano-LC). Six sympathomimetic drugs including ephedrine, norephedrine, synephrine, epinephrine, norepinephrine and norphenylephrine were separated by changing experimental parameters such as stationary phase, acetonitrile (ACN) content, buffer pH and concentration, column temperature. Four polar stationary phases (i.e. cyano-, diol-, aminopropyl-silica and Luna HILIC, a cross-linked diol phase) were selected and packed into fused silica capillary columns of 100 μm internal diameter (i.d.). Among the four stationary phases investigated a complete separation of the all studied compounds was achieved with aminopropyl silica and Luna HILIC stationary phases only. Best chromatographic results were obtained employing a mobile phase composed by ACN/water (92/8, v/v) containing 10 mM ammonium formate buffer pH 3. The influence of the capillary temperature on the resolution of the polar basic drugs was investigated in the range between 10 and 50 °C. Linear correlation of ln k vs. 1/T was observed for all the columns; ΔH° values were negative with Luna HILIC and positive with aminopropyl- and diol-silica stationary phases, demonstrating that different mechanisms were involved in the separation.To compare the chromatographic performance of the different columns, Van Deemter curves were also investigated. 相似文献
5.
Three novel chiral stationary phases (CSPs) were prepared by regioselective chemical immobilization of mono(6A-N-allylamino-6A-deoxy)perphenylcarbamoylated (PICD) α-, β-, and γ-cyclodextrins (CDs) onto silica support via hydrosilylation. Their enantioseparation properties in high performance liquid chromatography (HPLC) were evaluated with a large spectrum of racemates including flavanone compounds, β-adrenergic blockers, amines and non-protolytic compounds. The effect of CD's cavity size on enantioseparation abilities was studied and discussed. The results indicated that CD's surface loading at silica support played an important role in the enantioseparation on these CSPs under normal-phase conditions while inclusion phenomena contributed the major driving force under reverse-phase conditions. As expected, α-PICD demonstrated the best resolutions towards flavonone and most aromatic alcohols under normal-phase conditions with the highest surface loading; while Fujimura's competitive inclusion model can be applied to explain the better enantioseparations towards β-adrenergic blockers, amines and non-protolytic compounds with α- and β-PICD CSPs. γ-PICD CSP showed superior enantioseparation ability for sterically encumbered analytes like flavanone compounds under both normal-phase and reversed phase conditions. 相似文献
6.
以双-三氟甲烷磺酰亚胺离子([NTf2]-)、三氟甲基磺酸根离子([TFO]-)和六氟磷酸根离子([PF6]-)为阴离子,合成了含有丙基、丁基、壬基、乙苯基或氰甲基等阳离子取代基的聚合乙烯基咪唑基离子液体固定相,制备了13种离子液体石英毛细管色谱柱。考察了离子液体固定相结构与色谱柱McReynolds常数、热稳定性和测试化合物保留行为之间的构效关系,研究了阳离子取代基对固定相保留性能的影响规律;同时考察了测试化合物保留指数随温度变化的规律。结果表明,所合成的离子液体固定相具有较强的极性,其保留性能不仅与阳离子取代基的性质密切相关,而且受取代基结构和阴离子影响明显;在考察的温度范围内,测试化合物的保留指数变化规律与传统色谱固定相完全相同。 相似文献
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V. G. Berezkin 《Russian Chemical Bulletin》1999,48(10):1807-1816
Chromatographic characteristcs of aqueous solutions of inorganic electrolytes, a new class of stationary liquid phases (SLP)
for vapor-phase chromatography, are considered. The SLP are characterized by an unusually high selectivity to organic compounds
of the R-X type (R is a hydrocarbon radical, X is a polar group,e.g., hydroxyl, carboxyl, and amine; for instance, light C1-C6 alcohols are eluted from the column with a water-containing phase in the following order: hexanol<pentanol<butanol<propanol<ethanol<methanol).
The nature of the electrolyte used and its concentration in the water-containing SLP have a crucial influence on the column
selectivity and the degree of separation of the compounds subjected to chromatography. This feature provides the possibility
of controlling the column selectivity by changing the content of water vapor in the mobile phase.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1831–1840, October, 1999. 相似文献
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Summary A table of data for acidity, basicity, polarity and London potential for stationary phases is given. These provide guidance in choosing a stationary phase for a given task from the 26 substances listed. The indices are calculated from infra-red shifts of 1-chlorobutane and the visible wavelength shifts of l2 when they are dissolved in the stationary phases, from NMR estimates of acidity and basicity and from relative retention data. They replace the less reliable data of Burns and Hawkes. Methods of determining the indices are suggested that require only a gas chromatograph and can be applied by technicians with no specialized understanding of solution parameters. An attempt to add electron donoracceptor indices to the table was unsuccessful. A further table is given of the slopes of the log plots d(logt)/dC for use in extrapolating from one homologue to another on these stationary phases. 相似文献
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A. Ono 《Chromatographia》1980,13(9):574-575
Summary Adenosine, guanosine and inosine used as liquid phases in gas chromatography permits the separation of all six xylenol isomers. 相似文献
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M. B. Evans 《Chromatographia》1982,15(6):355-357
Summary The on-column oxidation of apolar and polar silicones used as gas chromatographic stationary phases is investigated. Even at 225° the effects of oxidation are found to be slight. Of the materials investigated the methylphenylsilicones are the most stable. 相似文献
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Toyohide Takeuchi Tomoo Miwa Rongzong Hu Jianhua Chu 《Journal of separation science》1995,18(12):745-748
The retention behavior of aromatic hydrocarbons and dansylamino acids on cation-exchangers modified with alkylammonium ions has been examined by microcolumn liquid chromatography. Several parameters affected the retention of analytes, involving concentration of the modifier in the mobile phase, its alkyl chain length and mobile phase composition. Stationary phases modified with a reagent having longer alkyl chains achieved better column efficiency. 相似文献
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Sanka N. Atapattu 《Journal of separation science》2022,45(9):1487-1492
The solvation parameter model system constants and retention factors were used to interpret retention properties of 39 calibration compounds on a biphenylsiloxane-bonded stationary phase (Kinetex biphenyl) for acetone-water binary mobile phase systems containing 30–70% v/v. Variation in system constants, phase ratios, and retention factors of acetone-water binary mobile phases systems were compared with more commonly used acetonitrile and methanol mobile phase systems. Retention properties of acetone mobile phases on a Kinetex biphenyl column were more similar to that of acetonitrile than methanol mobile phases except with respect to selectivity equivalency. Importantly, selectivity differences arising between acetone and acetonitrile systems (the lower hydrogen-bond basicity of acetone-water mobile phases and differences in hydrogen-bond acidity, cavity formation and dispersion interactions) could be exploited in reversed-phase liquid chromatography method development on a Kinetex biphenyl stationary phase. 相似文献
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O. Bordelanne M. H. Delville G. Félix C. Labrugère A. Thienpont C. Vidal 《Chromatographia》2000,52(1-2):51-57
Summary The preparation, characterization and potential liquid chromatographic applications of various organometallic iron complexes
silica stationary phases are presented. These new supports are synthesized by covalently linking ferrocene, as well as some
of its cationic derivatives, to appropriately derivatized silica support matrices. These columns exhibit moderate to high
selectivity towards the separation of polycyclic aromatic hydrocarbons (PAHs). A charge transfer retention mechanism has been
proposed. A comparison with a reference stationary phase, 3,5-dinitrobenzamide (DNB), to quantify the acceptor power of the
new stationary bonded phases, is also reported. Finally, the effect of varying the derivatives of the bonded metallocene on
PAHs retention is discussed. 相似文献
14.
Preparative-grade bonded β- and γ-cyclodextrin stationary phases were used as the packing material of liquid chromato-graphic analytical microcolumns. Although the resulting columns are characterized by relatively low efficiency, the high selectivity of the cyclodextrin phases nevertheless allows their successful use for the separation of different classes of isomeric compounds that are difficult to resolve on conventional LC stationary phases. Examples of baseline (or almost baseline) separations of a number of isomeric compounds, including isomeric polycyclic aromatic hydrocarbons, are presented to demonstrate the analytical potential of such columns. Retention behavior of the separated isomers is discussed based on the structure of the solute molecule and the possibility of its inclusion into the molecular cavity of cyclodextrin stationary phases. 相似文献
15.
Summary The synthesis of several electron-acceptor stationary phases has been reviewed the materials evaluated for their capacity to separate polyaromatic hydrocarbons (PAHs). Chemically bonded phases were obtained by the same procedure; the organosilane moiety is monofunctional and the HPLC behaviour is compared under identical conditions. Examples of PAHs separations are given.Presentedat the 13th International Symposium on Polynuclear Aromatic Hydrocarbons, Bordeaux, October 1–4, 1991. 相似文献
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New macrocyclic stationary chemically bonded phases were synthesized and tested in gas chromatography conditions. The complexes of 1,4,8,11-tetraazacyclotetradecane with Cu(II) and Co(II) were bonded to the silica support through the (3-chloropropyl)triethoxysilane reactant. The packings obtained were analyzed by diffuse-reflectance ultraviolet–visible spectroscopy (DRUV–Vis), differential thermal gravimetry (DTG), porosimetry, and elementary analysis. Preliminary study of the novel silica gas chromatography (GC) stationary phases containing cyclam complexes was carried out using packed 1/8 in. i.d. columns. The study was conducted on: cyclic, linear and branched olefins, aromatic hydrocarbons and ethers. Characterization of interactions between the compounds mentioned and new stationary phases was based upon analysis of Kováts retention indices (I), difference between retention indices for two phases (ΔI), and molecular retention indices (ΔMe). Results have shown that the new stationary phases interact sufficiently strongly with molecules of high electron density and can be applied in capillary gas chromatography for the analysis of light hydrocarbons. 相似文献
18.
B. T. Mathews A. E. Beezer M. J. Snowden M. J. Hardy J. C. Mitchell 《Chromatographia》2000,53(3-4):147-155
Summary The reversed phase chromatographic properties of the [G1]-L-glutamic and ethyl ester-AC-silica (1), [G2]-L-glutamic acid ethyl ester-AC-silica (2) and the [G1]-L-glutamic acidt-butyl ester-AC-silica (3) dendrimer stationary phases were evaluated. Initial studies involved the comparison between these phases with a classic
reversed phase (i.e. ODS1) by the separation of a standard reversed phase test mixture composed of dimethylphthalate, nitrobenzene,
anisole, diphenylamine and fluorene. Separations were achieved with comparable performance to those obtained with the conventional
reversed phase (ODS1). However, it was apparent that the chromatographic selectivity exhibited by the dendrimer stationary
phases was different from that of the ODS1 phase. On a per mole basis, the dendrimers exhibited similar (and sometimes greater)
affinity for these analytes compared with the ODS1 ligand. Subsequent chromatographic experiments were conducted upon the
dendrimer chiral stationary phases using chiral analytes under reversed phase and normal phase conditions. Chiral resolution
was not observed. 相似文献
19.
Two covalently bonded cationic β-CD chiral stationary phases (CSPs) prepared by graft polymerization of 6A-(3-vinylimidazolium)-6-deoxyperphenylcarbamate-β-cyclodextrin chloride or 6A-(N,N-allylmethylammonium)-6-deoxyperphenylcarbamoyl-β-cyclodextrin chloride onto silica gel were successfully applied in high-performance liquid chromatography (HPLC). Their enantioseparation capability was examined with 12 racemic pharmaceuticals and 6 carboxylic acids. The results indicated that imidazolium-containing β-CD CSP afforded more favorable enantioseparations than that containing ammonium moiety under normal-phase HPLC. The cationic moiety on β-CD CSPs could form strong hydrogen bonding with analytes in normal-phase liquid chromatography (NPLC) to enhance the analytes’ retention and enantioseparations. In reversed-phase liquid chromatography (RPLC), the analytes exhibited their maximum retention when the pH of mobile phase was close to their pKa value. Inclusion complexation with CD cavity and columbic/ionic interactions with cationic substituent on the CD rim would afford accentuated retention and enantioseparations of the analytes. 相似文献
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Summary The changes in the heat of solution of polar compounds and xylene isomers in methylsilicone fluid OV-101 deposited on Chromosorb W AW DMCS were studied. It was shown that the heat of solution increases with an increase of the percentage loading of the OV-101 up to 10%. Solution and adsorption thermodynamic characteristics of the studied system are briefly discussed. 相似文献