A novel technique for high-speed gas chromatography that uses simultaneous temperature gradients in both time and distance along a narrow-bore capillary column is described. An electrical resistance gradient along the column provides a temperature gradient such that the head of the column is always at a higher temperature than the end of the column. The gradient along the column continuously refocuses eluting bands, counteracting part of the chromatographic band spreading. With a properly defined temperature gradient surface, each substance reaches a focus capacity factor that is determined by the ratio of gradients in time and distance and by carrier gas velocity. The numerical value of this focus capacity factor is independent of the substance involved, but its trajectory in time and distance along the column depends on the thermodynamics of an individual substance's interaction with the stationary phase. A high-speed gas chromatogram showing baseline separation of 13 components within 3.5 s is shown to demonstrate the potential of this technique for very fast and efficient separations.
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Jain et al. (1995) studied this question.