Influence of concurrent retention mechanisms on the determination of stationary phase selectivity in gas chromatography

Kersten, Brian R.; POOLE, C

doi:10.1016/0021-9673(87)80053-5

Cited by 2 publications

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“…It must be pointed out that the retention in gas chromatography is a complex process involving partition between the gas and the liquid phase but also the adsorption at solid−liquid and gas−liquid interfaces. Therefore, the comprehensive retention model should consider not only the contribution resulting from the gas−liquid partitioning but also the adsorption occurring at the interface between the bulk liquid and the solid support and at the interface between the gas phase and the bulk liquid. − The classical equation taking into account partition and interfacial adsorption contributions in the GC mechanism can be written as follows − V N = V L K L + A G L K G L + A L S K G L S where V N , V L , A GL , and A LS are the net retention volume per gram of packing, the volume of liquid phase per gram of packing, the liquid surface area per gram of column packing, and the liquid−solid interfacial surface area per gram of column packing, respectively. K L , K GL , and K GLS represent the gas−liquid partition coefficient, the adsorption coefficient at the gas−liquid interface, and the coefficient for adsorption at the support surface, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Performing a series of measurements with increasing loading of the liquid phase makes it possible to extrapolate the V N / V L ratio against 1/ V L toward 1/ V L = 0 and to obtain the value of the gas−liquid partition coefficient, K L , independent of adsorption contributions. This approach was successfully used to obtain gas−liquid partition coefficients of polar probes. , Several studies on the influence of concurrent retention mechanisms on the determination of stationary phase selectivity showed that the n -alkanes were retained predominantly by interfacial adsorption on RTILs. ,, This can be explained because of the immiscibility of n -alkanes with polar salts. Ionic liquids can easily adsorb on solid surfaces and may form a strongly structured interface at the surface of the support.…”

Section: Introductionmentioning

confidence: 99%

“…24,28 Several studies on the influence of concurrent retention mechanisms on the determination of stationary phase selectivity showed that the n-alkanes were retained predominantly by interfacial adsorption on RTILs. 17,19,23 This can be explained because of the immiscibility of n-alkanes with polar salts. Ionic liquids can easily adsorb on solid surfaces and may form a strongly structured interface at the surface of the support.…”

Section: Introductionmentioning

confidence: 99%

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Activity Coefficients at Infinite Dilution of Organic Compounds in 1-Butyl-3-methylimidazolium Tetrafluoroborate Using Inverse Gas Chromatography

et al. 2008

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International audienceActivity coefficients at infinite dilution (γ∞) of organic compounds in the room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate were determined using inverse gas chromatography from (303.35 to 332.55) K. Retention data were used to estimate the influence of gas−liquid and gas−solid interfacial adsorption on the value of activity coefficients at infinite dilution of solutes in this ionic liquid. Most of the polar solutes were retained largely by partition, while n-alkanes were retained predominantly by interfacial adsorption on the ionic liquid studied. The solvation characteristics of the ionic liquid were evaluated using the Abraham solvation parameter model

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Activity Coefficients at Infinite Dilution of Organic Compounds in 1-Butyl-3-methylimidazolium Tetrafluoroborate Using Inverse Gas Chromatography

et al. 2008

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Sulfoxides as Urinary Metabolites ofS-Allyl-l-Cysteine in Rats: Evidence for the Involvement of Flavin-Containing Monooxygenases

Krause¹,

Glocke²,

Elfarra³

2002

Drug Metab Dispos

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ABSTRACT:S-Allyl-L-cysteine (SAC), a component of garlic and a metabolite of allyl halides, is a known substrate for multiple flavin-containing monooxygenases (FMOs). In the current study, we characterize the in vivo SAC metabolism by investigating the presence of SAC, N-acetyl-S-allyl-L-cysteine (NASAC), and their corresponding sulfoxides in the urine of rats given SAC (200 or 400 mg/kg i.p.). In some experiments, rats were given aminooxyacetic acid (AOAA), an inhibitor of cysteine conjugate ␤-lyase, or methimazole, an alternative FMO substrate, 30 min prior to treatment with 200 mg/kg SAC. Nearly 40 to 50% of the dose was recovered in the 24-h collection period. In all treatment groups, the majority of the metabolites were excreted within 8 h. The major metabolites detected were NASAC and NASAC sulfoxide (NASACS; nearly 30-40% and 5-10% of the dose, respectively). Only small amounts of the dose (approximately 1.5%) were recovered as SAC and SAC sulfoxide (SACS). Methimazole pretreatment significantly reduced amounts of both SACS and NASACS detected in the urine when compared with rats given SAC only, whereas AOAA pretreatment had no effect. In vitro assays using rat liver microsomes were also carried out to compare the sulfoxidation rates of SAC and NASAC. The results showed that SAC was much more readily oxidized than NASAC. Collectively, the results provide evidence for the involvement of FMOs in the in vivo metabolism of SAC and that SAC is a much better substrate for FMOs than its corresponding mercapturic acid. (SAC 1 ) is a significant water-soluble allyl sulfur component in garlic preparations (Weinberg et al., 1993), a component which has been shown to have antioxidant and anticancer properties in animals (Sumiyoshi and Wargovich, 1990;Hatono et al., 1996;Ho et al., 2001). SAC has been shown to have antiproliferative effects on neuroblastoma (Welch et al., 1992), melanoma (Takeyama et al., 1993), and prostate carcinoma cells (Pinto et al., 1997). However, the mechanisms of the anticancer properties of SAC are unclear. S-Allyl-L-cysteineSAC is also a known metabolite of allyl halides and allyl esters, including allyl chloride, allyl bromide, sodium allyl sulfate, and allyl nitrate (Kaye et al., 1972;Kaye, 1973). It results from the formation of the glutathione conjugate of the allyl halide or ester. The glutamate and glycine moieties of S-allyl-glutathione are then cleaved by ␥-glutamyl transpeptidase and dipeptidases to yield SAC.Our laboratory has previously shown that SAC is a substrate for multiple rabbit and human flavin-containing monooxygenases (FMOs). FMOs are microsomal enzymes that catalyze the NADPHdependent oxidation of many compounds that contain sulfur, nitrogen, selenium, and phosphorus (Ziegler, 1993). Previously, we have shown that SAC is metabolized to the greatest extent by cDNA-expressed rabbit FMO3 followed by FMO1 and then FMO2, but SAC showed no activity with rabbit FMO5 (Ripp et al., 1997). More recently and using cDNA-expressed human FMOs, SAC has been shown to be a good substr...

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Influence of concurrent retention mechanisms on the determination of stationary phase selectivity in gas chromatography

Cited by 2 publications

References 0 publications

Activity Coefficients at Infinite Dilution of Organic Compounds in 1-Butyl-3-methylimidazolium Tetrafluoroborate Using Inverse Gas Chromatography

Activity Coefficients at Infinite Dilution of Organic Compounds in 1-Butyl-3-methylimidazolium Tetrafluoroborate Using Inverse Gas Chromatography

Sulfoxides as Urinary Metabolites ofS-Allyl-l-Cysteine in Rats: Evidence for the Involvement of Flavin-Containing Monooxygenases

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