Fast comprehensive two-dimensional gas chromatography with cryogenic modulation

The fast separation of a mixture of 29 compounds by using comprehensive two-dimensional gas chromatography is reported. Capillary column sets with shorter lengths and smaller inner diameter in both the first and second dimensions have been tested, for both fast chiral and achiral separations. Fast chiral separations, which included enantiomer separations of limonene, linalool, citronellol, and alpha-isomethylionone, were achieved within 23 min, which corresponds to approximately 2-fold faster than analyses under conditions previously considered as normal. Fast achiral separations, which do not have the restriction of requiring a minimum quality of chiral resolution, were obtained within 5 min, which is markedly faster than separations on the normal column set under conditions more commonly employed. The achiral fast GC x GC method used a 5 m x 0.1 mm i.d. first dimension column, interfaced to a 0.3 m x 0.05 mm i.d. second column, with temperature program rate of 35 degrees C.min-1; a modulation period of 1 s was employed. Peak widths at baseline on the first column were a little over 1 s, while modulated peak widths at half-height recorded with a flame ionization detector operating at 200 Hz were approximately 30 ms. The benefits and limitations of GC x GC for fast chiral and achiral separations are reported and discussed.