Optimization of selectivity by tuning column temperatures for series-coupled capillary columns in dual-oven gas chromatographic systems

A method has been developed and evaluated for optimization of the selectivity of series-coupled capillary columns in a twin-oven gas chromatographic system in the shortest possible analysis time. The temperatures of either one or both columns were varied independently (partial optimization) or simultaneously (overall optimization), in order to separate the maximum number of sample components. The method is based upon computer-aided calculation of Kováts indices of the coupled columns by means of second and third order (polynomial) functions of the temperatures of the individual columns. The applicability and limitations of the methods are discussed and illustrated with separations of a synthetic hydrocarbon mixture of 33 components

Optimization of selectivity by tuning column temperatures for series-coupled capillary columns in dual-oven gas chromatographic systems

A method has been developed and evaluated for optimization of the selectivity of series-coupled capillary columns in a twin-oven gas chromatographic system in the shortest possible analysis time. The temperatures of either one or both columns were varied independently (partial optimization) or simultaneously (overall optimization), in order to separate the maximum number of sample components. The method is based upon computer-aided calculation of Kováts indices of the coupled columns by means of second and third order (polynomial) functions of the temperatures of the individual columns. The applicability and limitations of the methods are discussed and illustrated with separations of a synthetic hydrocarbon mixture of 33 components

DEPENDENCE OF GAS-CHROMATOGRAPHIC RETENTION DATA OF HYDROCARBONS ON THE FILM THICKNESS OF THE POLYDIMETHYLSILOXANE STATIONARY-PHASE.

Kovats indices of cyclic and aromatic hydrocarbons, separated by capillary gas liquid chromatography on polydimethylsiloxane capillary columns, were found to increase with increasing stationary phase film thickness. This effect is explained in terms of adsorption of the stationary phase on the active sites of the inner surface of the capillary column. Since the number of active sites is limited, the overall polarity of the polydimethylsiloxane stationary phase is better defined in columns with thick stationary phase films. Interlaboratory reproducibility of retention indices of cyclic and aromatic hydrocarbons is therefore also better when using capillary columns with thick films of the polydimethylsiloxane stationary phase. Retention data obtained on such thick-film columns are influenced by adsorption of the stationary phase on the column walls to a lesser extent than in columns with thinner films.</jats:p

Optimization of selectivity by tuning column temperatures for series-coupled capillary columns in dual-oven gas chromatographic systems

A method has been developed and evaluated for optimization of the selectivity of series-coupled capillary columns in a twin-oven gas chromatographic system in the shortest possible analysis time. The temperatures of either one or both columns were varied independently (partial optimization) or simultaneously (overall optimization), in order to separate the maximum number of sample components. The method is based upon computer-aided calculation of Kováts indices of the coupled columns by means of second and third order (polynomial) functions of the temperatures of the individual columns. The applicability and limitations of the methods are discussed and illustrated with separations of a synthetic hydrocarbon mixture of 33 components