Optimization of the separation of multicomponent mixtures by HRCGC

Matisová, Eva; Kovac̆ic̆ová, E.; Garaj, J.; Kraus, G.

doi:10.1007/bf02319572

Cited by 14 publications

(9 citation statements)

References 19 publications

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“…All these difficulties have encouraged experts to find out pioneering solutions. Two different approaches were initially proposed: the capillary column was coated with an homogeneous mixture of stationary phases ; two or more capillary columns with different stationary phases were connected in series . …”

Section: Introductionmentioning

confidence: 99%

GC models for separation optimization in pressure-tuneable tandem capillary columns operated isothermally. Part 1: Theoretical aspects

et al. 2013

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GC column selectivity can be continuously adapted to suit analytical needs using a flow-tuneable tandem system. Its application for the separation of complex mixtures requires a deep understanding of the theory in this area. Although a number of researchers have developed specific models, a general and exhaustive theory is still missing. In this paper, we have made an implementation of pre-existing models on tandem-column assemblies operated isothermally. In particular, we have investigated the effect of column length and diameter, phase thickness, and oven temperature on chromatographic parameters, such as capacity factor, selectivity, and intrinsic resolution. A new approach for the correct choice of the working temperature has been proposed.

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Section: Introductionmentioning

confidence: 99%

GC models for separation optimization in pressure-tuneable tandem capillary columns operated isothermally. Part 1: Theoretical aspects

et al. 2013

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“…This value was chosen because it results in a complete separation of components 1−14. A window diagram procedure was used to select this pressure. , Note that under these conditions peaks 17 and 19 show excessive overlap and 16 and 20 show nearly complete coelution. These features are all predicted by the model, and the actual retention times as well as the peak-elution pattern are in good agreement with the model predictions.…”

Section: Resultsmentioning

confidence: 99%

“…A more powerful and flexible approach to obtaining adjustable selectivity is to control the carrier-gas pressure at the junction point of two series-coupled capillary columns. ,,− Changes in the junction-point pressure result in differential changes in the average carrier gas velocities in the two columns. This causes differential changes in component residence times (retention times) for the two columns.…”

mentioning

confidence: 99%

Programmable Control of Column Selectivity for High-Speed GC

and

Sacks

1999

Anal. Chem.

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A tandem-column ensemble consisting of two capillary columns with different stationary-phase chemistries and computer-controlled carrier-gas pressure at the column junction point is used to change the ensemble selectivity on-the-fly during a separation. When the pressure at the column junction point is changed, differential changes occur in the carrier gas velocities in the two columns. This changes the relative contribution that each column makes to the ensemble selectivity. This programmable selectivity control is applied to the problem of high-speed, isothermal GC analysis of volatile organic compound (VOC) mixtures. For the ensemble configuration described here, the pressure control system provides over 200 computer-selected junction-point pressures in 0.1 psi steps. Repeatability typically is ±0.01 psi. This provides for very stable retention patterns. The relatively large dead volume in the controller is managed by the use of a pneumatic vent line. The vent line restriction is set to give pressure set-point transition times of 0.3−3 s. A model is developed to aid in the selection of the pressure program (pressure vs time profile) that will result in a rapid separation of the target compounds. The model results in plots of the position of component bands in the column ensemble vs time. These sample-band trajectory plots show discontinuous changes in slope (migration velocity) at pressure set-point change times and when each component band migrates across the column junction. The model provides quantitative information on elution peak positions. The model is used to predict the effects of changes in the selectivity program on retention patterns.

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“…The most straightforward and flexible approach is to combine two capillary columns with different stationary phases in series. By combining the columns in different proportions, the overall selectivity of the column ensemble can be tuned to any value within the limits imposed by the selectivities of the individual columns (27). To obtain a large tuning range the stationary-phase chemistries of the two columns should be verv different The combination of a polyethvlene glycol (wax) phase and a poly(dimethyl siloxane) (gum) ohase has been shown to be useful (26 28) An adjustable pressure at the junction point between the columns can control the structure of the elution patterns from the tandem column ensemble (29)(30)(31).…”

Section: Two-dimensional Ssparationsmentioning

confidence: 99%

Peer Reviewed: High-speed gas chromatography

Sacks¹,

Smith²,

Nowak³

1998

Anal. Chem.

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Emerging technologies have made high-speed GC practical and useful for an increasing range of applications.C and GC/MS are the most frequently used methods for the speciation and quantification of volatile and semivolatile organic compounds. The total cost for these analyses is enormous. Protracted sample turnaround times, which are common for contract laboratories, cause expensive bottlenecks. Dramatic reductions in analysis time could lead to significant economic advantages for applications involving environmental and chemical process monitoring. This Report considers several emerging technologies that have made high-speed GC (HSGC) practical and useful for a rapidly increasing range of applications Slow road to high speedThe potential for a favorable trade of resolution for speed was recognized soon after the development of the open-tubular separation column by Golay in 1957 (1). In 1962 Desty and co-workers (2) used a gas-tight syringe, which was struck by a mallet, to introduce a 10-ms vapor plug into a 2-m long, 0.07-mm i.d. wall-coated metal capillary column. The result was the separation of all nine heptane isomers in about 5 s. A mirror galvanometer array and photographic paper recorded the chromatograms.Wall-coated open-tubular (capillary) GC columns were slow to win acceptance; high-speed capillary column GC, even slower. In part, this resistance was caused by the extraordinary resolving power of long capillary columns, which focused research attention on the separation of increasingly complex mixtures. As a result, analysis time and selectivity became less frequent topics for research. The number of widely used stationary phases dwindled, and the one-size-fits-all approach to methods development became common Often, the column length and the temperature-programming profile are ad-

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Optimization of the separation of multicomponent mixtures by HRCGC

Cited by 14 publications

References 19 publications

GC models for separation optimization in pressure-tuneable tandem capillary columns operated isothermally. Part 1: Theoretical aspects

GC models for separation optimization in pressure-tuneable tandem capillary columns operated isothermally. Part 1: Theoretical aspects

Programmable Control of Column Selectivity for High-Speed GC

Peer Reviewed: High-speed gas chromatography

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