You can actually have it setup to do both, purge and trap and direct injection if you want to have more versatility in your system. If the transfer line from the purge and trap is tapped into the stainless steel supply line going into the side of the injection port so that you still have access to the septum for injections, then you are ready to go. The carrier gas will just pass through the purge and trap before entering the injection port. If you have the transfer line placed through the septum then you need to replumb the setup.
If you have the first setup I mentioned, then all you must do to remove the purge and trap from the system it find the tubing going from the flow controller on the 5890, out to the purge and trap carrier gas inlet fitting. Remove that line and then use a connector to rejoin it to where the transfer line is attached to the side of the inlet. (these should be the same size lines since most of the time people just cut the normal inlet supply line and rerouted it to the purge and trap then connected the transfer line back to where the line was cut)
I have run the setup before where I had a purge and trap and a tower autosampler on the same column in a 5890 with no problems, using either the direct inject port or the split splitless port. I had one setup to run Gasoline Range Organics by purge and trap FID then inject Diesel Range Organics through the split splitless port without even changing columns. Just need something like a 60m x 0.32mm x 1um film DB5 or DB1 type column.
