Split injections are widely used because its easy and the amount allowed onto the column can be adjusted with the split-vent flow. Split injections are therefore applicable for measurement of components that have % levels, down to ppm levels.
For several reasons, there is interest in replacing helium with a different carrier gas in gas chromatography. Hydrogen is the obvious choice but there is a concern on safety and reactivity. It is also possible to use nitrogen but this is often not considered because it has a low optimal flow and velocity.