All oxygen measurement systems so far available are characterized by a lack of suitable precision and/or required limit of detection, which would be essential for a great variety of applications. In this paper, a novel oxygen chamber together with a completely new concept of sample application ("two-chamber-siphon technique") is presented which can be used in combination with the previously reported chromatographic oxygen sensor (part 1). This new oxygen-sensing assay exhibits several advantages in comparison to conventional oxygen measurement systems: e.g., the uncontrollable influence of the surrounding atmosphere as well as oxygen consumption and storage processes are excluded. For the first time, measurements of molecular oxygen below 1 × 10(-)(7) mol L(-)(1) can be performed. Reliable quantification of oxygen in liquids and also in gaseous and solid samples can be achieved with utmost sensitivity (LOD 4.9 × 10(-)(9) mol L(-)(1) O(2) = 98 fmol of oxygen on column) and precision (RSD = 0.7%, n = 8).