3. Direct line coupling, without splitter

The virtual disappearance of packed columns has rendered most molecular separators obsolete. Direct connection of a capillary column to a mass spectrometer is now the rule in all commercial GC-MS systems. However, even in the absence of a specific interfacing device, there are several ways of connecting a GC column directly to a mass spectrometer source, depending on the dimensions of the GC column, the vacuum pumping capabilities of the mass spectrometer, and the operating constraints specific to the laboratory (e.g. frequency of column exchange).