A flow apparatus for a spectrometer system includes a first optics element that is optically coupleable to a spectrometer and a second optics element that is optically coupleable to a light source. The first and second optics element may be arranged at a distance from one another in the region of a measurement gap through which a liquid can flow, in the region of which a light beam emerging from the second optics element and propagating into the first optics element is at least partly absorbable. A through-flow amount of the liquid through the measurement gap is controllable by changing the distance between the two optics elements, such that the spectrometer system can be used with various different samples.