How does ZB-guardian/ Z-guard act as retention gap column in a large volume injection?

In a large volume injection, 5-100µL of the solvent is injected into the GC inlet. The vapor volume of the solvent is approximately 1000 times the liquid volume (depending on the solvent the vapor volume varies). ZB-guardian/ Z-guard acts as a retention gap column forcing the solvent farther away from the analytes and allowing the analytes to focus as sharp band on the analytical column’s head.