These features allow for completely automated peak finding and spectral deconvolution of relatively narrow and severely overlapping chromatographic peaks from completely unknown mixtures. This reduces the chromatographic resolution requirements, and can result in order-of-magnitude reductions in the time required for mixture characterization. For HSGC analysis of characterized samples, selectivity is enhanced by the use of programmable carrier gas flow in a series-coupled ensemble consisting of a polar and a non-polar column. A valve connecting the column junction point to a ballast chamber containing carrier gas at the GC inlet pressure is used to stop the flow in the first column for short, programmed intervals in order to achieve greater separation of targeted component pairs that are separated by the first column in the ensemble, but co-elute from the ensemble. High-speed characterization and analysis of grapefruit oil is used to demonstrate these technologies. Using a temperature-programming rate of 50oC/min, complete characterization and analysis are achieved in less than 200s.