Because of its essential role, the modulator is the most critical part of a GC × GC instrument.It has been reported that a number of trapping anomalies have been observed during cryogenic modulation, however, few of these have appeared in the literature.Examples of these include the appearance of double spots for a single compound where more than one spot occurs at the same first dimension time, but different second dimension times in the 2D GC × GC space.This will complicate quantification-and identification of compoundsconsiderably.Additionally, it has been observed that peaks might not be effectively released from the trapping region during the heating stage if the cooling is re-applied too quickly, or is too cold.This leads to extended bands within the 2D space.