In this case, analytes will be trapped there for some time and will be released later to the second column. Another possibility is to work with two independent ovens. One GC with two ovens can be used (for example the well-know Sichromat 2-8 from Siemens, unfortunately no longer manufactured). Or, like in our laboratory where two GCs are connected together by means of a heated transfer line.When working with two ovens, it is not necessary to use a cryogenic trap. In this case,
the heart-cut from the first column is sent to the second oven where the temperature is
lower and then the analytes will be trapped at the beginning of the column until the
temperature program starts. In all cases the most important part is the switching system, which will transfer the analytes from one column to the other.