Proposed substitution of apolane-87 for squalane as a nonpolar reference phase in gas chromatography

Poole, Colin F.; Pomaville, Rena M.; Dean, Thomas A.

doi:10.1016/s0003-2670(00)84607-3

Cited by 23 publications

(9 citation statements)

References 31 publications

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“…Squalane is readily available and has been widely used in gas chromatography providing access to a potentially large database of recorded retention data. 28,30,31 A detailed study of the retention properties of squalane was undertaken to ascertain its suitability as a replacement for hexadecane for the chromatographic determination of logL 16 over the temperature range 60-120 °C.…”

Section: Resultsmentioning

confidence: 99%

“…For squalane, and probably other hydrocarbon phases as well, coalescence to a continuous film on silanized diatomaceous earth supports does not occur until at least moderate phase loadings are reached. 31,32 Consequently, nominal phase loadings in the range 8 to 20% (m/m) were studied to minimize solute interactions with the silanized support. The contribution of interfacial adsorption to retention and the gas-liquid partition coefficients were determined through eqn.…”

Section: Resultsmentioning

confidence: 99%

“…The absence of polar impurities at detectable concentrations was confirmed by supercritical fluid chromatography and NMR spectroscopy. 31 The models in Table 5 should be suitable for the determination of logL 16 by gas-liquid chromatography on squalane. The preferred method would be to use log K L as the dependent variable, since the only additional solute descriptor required is the excess molar refraction R 2 , which can be estimated with sufficient accuracy from structure or calculated directly from the refractive index of liquids.…”

Section: Resultsmentioning

confidence: 99%

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Chromatographic methods for the determination of the logL16 solute descriptor

Poole

Kiridena³

et al. 2000

Analyst

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A squalane packed column and two open-tubular columns coated with an immobilized stationary phase film of poly(dimethylsiloxane) or poly(methyloctylsiloxane) are evaluated as surrogate chromatographic systems for the determination of the logL16 solute descriptor by gas chromatography. Retention on the squalane column is dominated by gas-liquid partitioning with a significant temperature-dependent contribution from interfacial adsorption at the liquid-solid interface. Using the gas-liquid partition coefficient as the dependent model variable allows logL16 to be estimated to +/- 0.026 log units over the temperature range 60-120 degrees C. Without correction for interfacial adsorption a single column estimation of logL16 with phase loadings of 8 to 20% (m/m) over the temperature range 80-120 degrees C is possible for compounds with moderate hydrogen-bond basicity. The poly(dimethylsiloxane) stationary phase is both dipolar and hydrogen-bond basic and less suitable than the poly(methyloctylsiloxane) stationary phase, which is less cohesive and has similar dipolarity but no hydrogen-bond basicity. The determination of logL16 on the poly(methyloctylsiloxane) column requires prior knowledge of the solute dipolarity/polarizability descriptor to avoid significant errors in the measurement of logL16 for polar compounds. In such circumstances a single column estimation of logL16 over the temperature range 60-140 degrees C with an error of +/- 0.05-0.09 log units is possible.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Chromatographic methods for the determination of the logL16 solute descriptor

Poole

Kiridena³

et al. 2000

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“…This rate coefficient is about 50 times smaller than the binary collision limited reaction rate constant in the gas phase (B5 Â 10 À10 cm 3 molec À1 s À1 ). Squalane, however, has a viscosity of 17.9 cP, 34 which is 60 times larger than that of hexane. Assuming a molecular radius of 1 nm (approximated from molecular density of liquid squalane) the diffusion coefficient for squalane is computed to be 1 Â 10 À7 cm 2 s À1 , which is reasonably consistent with the range of diffusion coefficients of various solutes 35,36 (0.25-1.4 Â 10 À6 cm 2 s À1 ) in squalane as well as triacontane 37 (7.5 Â 10 À7 cm 2 s À1 )-the solid straight chain isomer of squalane.…”

Section: Kinetic Modelmentioning

confidence: 94%

The direct observation of secondary radical chain chemistry in the heterogeneous reaction of chlorine atoms with submicron squalane droplets

Liu

Smith

Dung

et al. 2011

Phys. Chem. Chem. Phys.

100

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“…Of the five descriptors needed to describe a molecule, the McGowan volume, V i , is the only one that can be calculated via a simple, strictly additive incremental method [9]. The L i value of a compound can be determined from its net retention volume on an Apolane-87 gas chromatographic (GC) column (Alltech, Deerfield, IL, USA) provided that this column has previously been characterized by measuring the net retention volumes of a set of calibration compounds [10,11]. Similarly, a chemical's S i and A i value can also be determined from GC-retention measurements if suitable and calibrated columns are used and if the L i value is known already.…”

Section: Methodsmentioning

confidence: 99%

Nonadditive effects in the partitioning behavior of various aliphatic and aromatic molecules

Goss¹,

Arp²,

Bronner³

et al. 2009

Enviro Toxic and Chemistry

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Predicting the partition behavior of bifunctional molecules from their molecular structure is a challenge because the combination of two or more functional groups often has nonadditive effects. Data presented here and in the literature reveal that isomers of bifunctional compounds can exhibit partition constants that differ by several orders of magnitude. These effects are not limited to compounds with intramolecular H-bonds. For aliphatic molecules, large effects are found for diones and diesters but not for dioles. For aromatic molecules, large effects are found for compounds with intramolecular H-bonds and also for p-isomers with a strong delocalisation of pi-electrons over both functional groups as in p-nitroaniline and p-nitrophenol. Interestingly, these nonadditive effects apply not only to the specific interactions but also to the van der Waals interactions of a molecule. This diversity of possible nonadditive effects makes it difficult to predict partitioning of such polyfunctional molecules. Our results suggest that successful models require either an extensive number of correction factors or a quantum chemical approach. Predicting partitioning of bifunctional molecules to environmental systems might face an additional complication. Unlike with solvents, steric limitations of natural phases may prevent them from forming multiple H-bonds with bifunctional molecules. Our experimental results, however, indicate that this situation does not occur, as the H-bond-interaction behavior of bifunctional molecules in humic matter and on quartz was the same as it was in various solvent systems.

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Proposed substitution of apolane-87 for squalane as a nonpolar reference phase in gas chromatography

Cited by 23 publications

References 31 publications

Chromatographic methods for the determination of the logL16 solute descriptor

Chromatographic methods for the determination of the logL16 solute descriptor

The direct observation of secondary radical chain chemistry in the heterogeneous reaction of chlorine atoms with submicron squalane droplets

Nonadditive effects in the partitioning behavior of various aliphatic and aromatic molecules

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