A method for the in-instrument recombination of volatiles using a gas chromatograph with mass spectrometry and olfactometry detection is described. Compounds that are introduced into the modified GC are separated conventionally on an analytical capillary GC column. The elution profile of volatiles can be segmented, analyzed and arbitrarily combined. In-line with the GC column, a pneumatic flow switch and splitter are connected to a detector and olfactometer. A cold trap allows the user to build a mixture of separated volatiles that is held until the cryotrap is rapidly heated, releasing the mixture for a subject to smell at the olfactory port and to evaluate. The instrument allows for characterization of the aroma quality of specific fractions of aroma volatiles obtained from foods, flowers or beverages without the need for pure chemical standards or the calculation of individual compound concentrations or sensory thresholds.