Patent attributes
A method for detecting substances or mixtures of substances within a sample in an apparatus for comprehensive two-dimensional gas-chromatographic analysis according to the present invention, comprising the steps of:subjecting the sample to a first separation within a first capillary column;modulating in time the effluents from the first column by means of the subdivision into adjacent fractions of the effluents from the first column and subsequently sending each fraction into a second capillary column, the modulation of the effluents being periodic with a first modulation frequency f1 of the sample;separating each of the fractions in the aforesaid second capillary column; anddetecting, at the end of the second capillary column, the effluents by means of periodic sampling by discrete time points at a second frequency f2.
