Mixed stationary phases in gas—liquid chromatography

Fernández-Sánchez, Elena; Fernández‐Torres, A.; García-Domínguez, José Antonio; Garcı́a-Muñoz, J.L; Menéndez, Vicente; Molera, M. J.; Santiuste, J. M.; Pertierra-Rimada, E.

doi:10.1016/s0021-9673(00)90031-1

Cited by 13 publications

(4 citation statements)

References 20 publications

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“…Although this is a rough estimate, the validity of the distribution coefficient was proved by the agreement between the model and the experimental data. Furthermore, upon comparison of the experimentally determined distribution coefficient with gas chromatographic data (18)(19)(20) and thermodynamic data (21) obtained from the literature, good agreement was found. Both the capacity factor (eq 3) and the Biot number (eq 4) are affected by the distribution coefficient, as illustrated by hexane, tridecane, and BHT in Figure 3.…”

Section: Resultssupporting

confidence: 54%

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Theoretical model for quantitative determination of volatile compounds in polymers by dynamic headspace sampling

Hagman¹,

Jacobsson²

1989

Anal. Chem.

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A theoretical model was derived for dynamic headspace sampling of volatiles in solid samples, such as polymers, and In which process parameters as well as component parameters were Included. The model assumes that the mass transfer from the polymer to the surrounding gas phase is accomplished by two rate constants, one within the polymer and one In the boundary gas layer at the polymer interface. By use of the model the recovery can be determined, which simplifies the quantification. The calculated and the experimental results show very good correlation under different types of conditions. The effects of variation of some process parameters (e.g. temperature and flow rate) on the recovery were also studied. Under the studied temperature range, as high a temperature as possible, but lower than the melt index for the polymer, gives the best possibility to achieve highest recovery for less volatile compounds. However, the best solution for all types of compounds is to have a small film thickness and as high a contact area as possible. A decisive parameter is the thickness of the boundary layer, which should be minimized as far as possible to achieve rapid transport In the gas phase. The mass transfer through this layer is often the rate-determining factor for the extraction efficiency. The flow rate optimum is determined by the geometry of the headspace sampler, type of extraction gas, and the cold trap efficiency.

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Section: Resultssupporting

confidence: 54%

“…K was experimentally determined by gas chromatography (using the same column as described in the experimental part) and is given by K = kYg/Va (18) where k' = capacity factor, Vg = volume of the gas phase, and Va = volume of the stationary liquid phase.…”

Section: Resultsmentioning

confidence: 99%

Theoretical model for quantitative determination of volatile compounds in polymers by dynamic headspace sampling

Hagman¹,

Jacobsson²

1989

Anal. Chem.

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show abstract

“…Two liquid phases, A and S, of different selectivity are chosen. However, the predictive ability for polar phases is not always that good, most likely due to retention occurring by a mixed mechanism (see section 2.5.1) [424]. A standard solute for which K R(A) ° and K R(S) ° are accurately known is included in the trial chromatograms to allow retention time data to be converted into K R° values.…”

Section: Mixturesmentioning

confidence: 99%

“…It is not necessary to blend liquid phases prior to coating, since it has been shown that mechanically mixed column packings of the pure phases provide the same results [424][425][426]. The window diagram approach can be used to optimize the temperature for a separation, but the method itself is intended primarily for use in isothermal gas chromatography.…”

Section: Mixturesmentioning

confidence: 99%