We disclose a microfabricated device for both extracting and preconcentrating samples for gas chromatography analysis. The device includes a conduit with at least two sections and multiple ports which may be connected to multiple gas chromatography columns. The inner surface of the conduit may be coated with multiple sorbents which bind volatile analytes with different affinities. The sections of the conduit may be divided by a thermal barrier which inhibits heat transfer between sections. Consequently, each section may be independently heated to encourage desorption of volatile analytes. The disclosed device separates and concentrates volatile analytes into different pools according to their chemical and physical properties before they enter a gas chromatography column that is optimized for that pool. The device reduces the amount of heat and time needed to perform gas chromatography analysis as well as avoids the need for purified gas sources typically used for the moving phase.