Spectroscopic measurement for containers

One aspect relates to a container, in particular a bioreactor and / or mixing vessel comprising: - an outer wall (101) which is adapted to enclose a medium; and - a spectroscopic cell (1), which is arranged in and / or on the outer wall (101), the spectroscopic cell (1) comprises: - a first optical surface (10); - a second optical surface (11) which is disposed the first optical surface (10) opposite to the first optical surface (10) and the second optical surface (11) are adjustable to one another in at least two different distances; and - is locates a sample space (12) disposed between the first optical surface (10) and the second optical surface (11), wherein in a measurement distance of at least two different distances of the sample chamber (12) with the medium can be filled, and wherein the performing a spectroscopic measurement, an optical surface is formed at least translucent.