In order to properly configure the system, several parameters must be considered. The most obvious is, of course, the choice of analytical column. The most resolution is obtained with narrow bore capillary columns, but stricter attention must be paid in the transfer of the sample to the column. On the other end of the spectrum, packed columns afford the use of larger samples (even preparative scale for recovery of bulk purified components), but at a sacrifice of chromatographic resolution. Between narrow bore capillary and packed columns lie wide bore capillary columns (also called megabore), and many laboratories find these to be a very useful compromise.
Narrow bore capillary columns have the advantage that they can be directly interfaced to the mass spectrometer. While a GC/MS 'interface' is used even in these cases, it is to provide termperature control of the column between the instruments. Wide bore capillary columns and packed columns can be used with GC/MS, but are a more complex interface; the most common such interface is a jet separator that allows most of the carrier gas (and much of the sample) to be discarded. As with simple GC instruments, packed columns can be directly interfaced on the inlet end, while capillary and wide bore columns require a more sophistication.