A method applies retention-time locking to multidimensional gas chromatography. Said play between the components can be eliminated by moving or bracing at least said two components towards or against each other with the aid of a hydraulic mechanism. Part of the light beam is preferably reflected by the sensor directly onto a second optoelectronic sensor. Finally, the method includes determining a failure state responsive to detecting a lapse in time from the request beyond the timeout value without response by the microcontroller. Methods of operating the system are also provided.