Numerical extrapolations for retention time prediction in capillary gas chromatography

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Virginia Tech

If the gas chromatographic retention behavior of a compound is known under isothermal conditions at several temperatures, then it is possible to predict accurately the retention time under temperature programmed conditions. This work details the calculations required to perform such predictions. A discussion of isothermal and temperature programmed retention is presented, along with a discussion of carrier gas flow relationships. These theories are then applied to the problem of predicting temperature programmed retention times from isothermal data. It is shown that accurate and precise predictions are possible for many situations. These predicted retention times are then applied to qualitative analysis by the use of retention indices. An architecture for a retention time or index database is proposed. Finally, the use of gas chromatography for the determination of thermodynamic quantities and gas viscosities is demonstrated.