There are different techniques available to inject the sample, each having its advantage.
Via a sample loop volumina from 10 µl to 10 ml can be injected onto the column. The advantage of sample loops is their cost effectiveness , little sample loss and high reproducibility of the injection.
A Superloop is a cylinder with a moveable seal inside. On the one side of the seal is buffer on the other side is sample. The seal prevents sample dilution. Another advantage is that little sample is lost and repeated injections of the same sample without manual interaction are possible. There are superloops with volumes up to 150 ml available.
If injection volumina are large a dedicated sample pump can be of great advantage, for example in Affinity Chromatography.
An Autosampler is the right choice when many different sample have to be injected fully automatically. It is suitable for injection volumes form 1 µl to 10 ml and it also available with cooling option.