Organics

Nubbe, Mary E.; Adams, V. Dean; Watts, Richard J.; Clark, Yvette R.

doi:10.1002/j.1554-7531.1992.tb00006.x

Cited by 3 publications

(11 citation statements)

References 436 publications

(3 reference statements)

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“…NMR Spectroscopy. 13 C CP/MAS NMR spectra were obtained by use of a Bruker ASX 300 instrument with samples of 200-300 mg in double-bearing 7-mm rotors of ZrO 2 . Sample spinning was executed at 4000 Hz, the proton 90°pulse length was 7 µs, and the contact time and delay time were 3 ms and 1 s, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…1D WIN-NMR software (Bruker, Rheinstetten, Germany) was used to process the solid-state NMR spectra. Zero filling to 2K data points and an exponential multiplication of the free induction decay (FID) with a line broadening of 30 Hz were performed before Fourier transformation of the 13 C CP/MAS NMR as well as for the 13 C MAS NMR spectra.…”

Section: Methodsmentioning

confidence: 99%

“…These compounds differ very little in polarity, and the separation of complex isomeric mixtures can present a significant challenge to the analyst. Polycyclic aromatic hydrocarbons (PAHs) exemplify such a separation challenge, and the determination of PAHs has been the subject of numerous reviews. − In general, better separations of PAH isomers can usually be achieved with stationary phases prepared by polymeric surface modification chemistries (compared with monomeric surface modification). , Other factors have been shown to influence shape recognition in LC, including stationary-phase bonding density, − alkyl-phase chain length, , and column temperature …”

mentioning

confidence: 99%

“…Materials were prepared with three levels of acrylic acid (mass fractions of 5, 10, and 15%) and with two types of linkages ((aminopropyl)triethoxysilane-and (glycidoxypropyl)trimethoxysilane-modified silica). The new RP materials have been characterized by 13 C cross polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy, and aspects of shape discrimination are examined for the separation of selected PAHs. 13 C MAS NMR measurements reveal that alkyl chain conformation differs with the composition of the polymer, and the data are further correlated with selectivity differences of these materials.…”

mentioning

confidence: 99%

“…The new RP materials have been characterized by 13 C cross polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy, and aspects of shape discrimination are examined for the separation of selected PAHs. 13 C MAS NMR measurements reveal that alkyl chain conformation differs with the composition of the polymer, and the data are further correlated with selectivity differences of these materials. Finally, the separation of mono-, di-, and tri-cis isomers of β-carotene is demonstrated.…”

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confidence: 99%

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Poly(ethylene-co-acrylic acid) Stationary Phases for the Separation of Shape-Constrained Isomers

et al. 2001

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A new approach for the synthesis of long alkyl chain length stationary phases for use in reversed-phase liquid chromatography is described. Poly(ethylene-co-acrylic acid) copolymers (i.e., (-CH2CH2-)x[CH2CH(CO2H)-]y) with different levels of acrylic acid were covalently bonded to silica via glycidoxypropyl or aminopropyl linkages. 13C cross polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy was used to characterize the new reversed-phase materials. Aspects of shape selectivity were evaluated for six different columns with Standard Reference Material (SRM) 869a, Column Selectivity Test Mixture for Liquid Chromatography. Selectivity for isomer separations was enhanced for stationary phases prepared with poly(ethylene-co-acrylic acid) containing a mass fraction of 5% acrylic acid. The relationship between alkyl conformation and chromatographic properties was studied by 13C magic angle spinning (MAS) NMR measurements, and correlations were made with the composition of the polymer. Finally, the effectiveness of this phase is demonstrated by the separation of several beta-carotene isomers.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Poly(ethylene-co-acrylic acid) Stationary Phases for the Separation of Shape-Constrained Isomers

et al. 2001

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Detection and determination limits of priority organic pollutants in soil

Terytze

Kördel²,

Aldag³

et al. 1995

Chemosphere

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Novel Approach for the Separation of Shape-Constrained Isomers with Alternating Copolymer-Grafted Silica in Reversed-Phase Liquid Chromatography

et al. 2010

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This paper describes a novel packing material for high selective reversed-phase high-performance liquid chromatography (RP-HPLC). The organic phase on silica is chemically designed in a way that the weak interaction sites are integrated with high orientation along the polymer main chain and high selectivity can be realized by multiple interactions with solutes. For the above purpose, we synthesized poly(octadecyl acrylate-alt-N-octadecylmaleimide)-grafted silica (Sil-poly(ODA-alt-OMI)) stationary phase. The alternating copolymerization was carried out from 3-marcaptopropyltrimethoxysilane (MPS)-modified silica via surface-initiated radical-chain transfer reaction. Elemental analysis, diffuse reflectance infrared Fourier transform (DRIFT),(1)H NMR, solid-state (13)C cross polarization magic angle spinning (CP/MAS) NMR, and suspended-state (1)H NMR were used to characterize the new organic phase. Aspects of shape selectivity was evaluated with Standard Reference Material (SRM 869b), Column Selectivity Test Mixture for Liquid Chromatography. Enhanced molecular shape selectivity was observed, that lead to the separation of SRM 1647e (16 polycyclic aromatic hydrocarbons, PAHs) in an isocratic elution. The effectiveness of this phase was also demonstrated by the separation of several beta-carotene and tocopherol isomers. The complete baseline separation of the tocopherol isomers was achieved using the Sil-poly(ODA-alt-OMI) phase. Chromatographic study revealed that Sil-poly(ODA-alt-OMI) has extremely high separation ability compared to monomeric and polymeric C(18) columns. Higher shape selectivity of the new RP material can be explained by a pi-pi and dipole-dipole interaction mechanism.

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Organics

Cited by 3 publications

References 436 publications

Poly(ethylene-co-acrylic acid) Stationary Phases for the Separation of Shape-Constrained Isomers

Poly(ethylene-co-acrylic acid) Stationary Phases for the Separation of Shape-Constrained Isomers

Detection and determination limits of priority organic pollutants in soil

Novel Approach for the Separation of Shape-Constrained Isomers with Alternating Copolymer-Grafted Silica in Reversed-Phase Liquid Chromatography

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