The main advantages of open tubular liquid chromatography (OTLC) over conventional packed-column liquid chromatography are the gain in resolution and the increased permeability. At present the reproducible preparation of narrow-bore columns and the lack of suitable commercial chromatographic equipment delay the development of OTLC. There are stringent requirements for injectors and detectors for OTLC with respect to their volumes, geometry, and contributions to the total band broadening. In this work some properties of two different sampling systems for OTLC were studied with respect to the accuracy and repeatability of the injected volumes. An approach is presented and discussed to determine the profile factors of these injection systems.