A modulator for simply providing fast and precise sampling of a chromatographic peak eluting from a first column into a second column of a comprehensive two-dimensional gas chromatograph, where the modulator includes a planar component containing a first gas passage for connecting a carrier gas source to the second separation column, a second gas passage for connecting the first separation column to an exhaust outlet, a connecting gas passage between the first and second gas passages, and two individually controllable open/close valves arranged in parallel connection in the first gas passage between its connection to the carrier gas source and the branch-off of the connecting gas passage, and where the gas passages and valves are formed in the planar component by micromachining.