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Optimizing the relationship between chromatographic efficiency and retention times in temperature‐programmed gas chromatography
Author(s) -
Mjøs Svein A.,
Waktola Habtewold D.
Publication year - 2015
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201500364
Subject(s) - van deemter equation , chemistry , gas chromatography , chromatography , kovats retention index , analytical chemistry (journal) , two dimensional gas , inverse gas chromatography , retention time , analyte , capillary action , thermodynamics , high performance liquid chromatography , physics
A methodology that can maximise the chromatographic efficiency that can be achieved within a defined time frame in temperature‐programmed gas chromatography is described. The efficiency can be defined as the inverse of peak widths measured in retention index units. This parameter can be described by a model similar to the van Deemter equation, which is expanded to account for the effect of the temperature rate in addition to the effect of carrier gas velocity. The model of efficiency is found by response surface methodology, where the temperature rates and the carrier gas velocities are systematically varied in the experiments. A second model that accurately explains the retention time of the last eluting compound can be found from the same experiments, and optimal conditions are found by combining the two models. The methodology has been evaluated with four capillary columns and three carrier gases, using fatty acid methyl esters as analytes. All experiments showed that there is a fairly linear decrease in efficiency with increasing temperature rates. At any temperature rate, optimal velocity is only marginally higher than the velocity that maximises chromatographic efficiency, since the carrier gas velocity has a limited effect on the retention times.