Sample-Holding Element, Analysis Set, and Method for Analyzing a Liquid, in Particular a Cooling Lubricant Emulsion

A sample-holding element (20) for a liquid sample for simultaneous analysis of three or more chemico-physical parameters of the liquid by an analysis device, the sample-holding element (20) comprising:

• a sample-holding space (31) that can be filled with the liquid;
• at least three measuring points (24, 25, 26, 26N, 27) in adjacent arrangement with respect to each other distributed across the sample-holding space (31), wherein two of the measuring points (24, 25) are a photonic measuring point (24) and a refractive index measuring point (25), and wherein the at least one further measuring point is selected from the group consisting of at least one pH measuring point (26), one conductivity measuring point (27), and one germ measuring point;
• wherein the sample-holding element (20) is a planar element (20) that is double-walled at least in sections and comprises two planar-parallel plates (30, 30′) arranged on top of each other that are connected to each other, wherein the sample-holding space (31) is designed in the form of a gap in planar manner between the two plates (30, 30′);
• wherein the plates (30, 30′) are connected to each other at least in sections at their edges, wherein an opening of the sample-holding element (20) is formed by the non-connected parts of the edge, and a distance between the plates (30, 30′) is just so large that the liquid sample between the double walls (30, 30′) can be subjected to the capillary effect;
• wherein the measuring point (25) for the refractive index measurement comprises a prism structure (25′, 25″) at one of the plates (30, 30′) in a predetermined area, wherein the plates (30, 30′) are transparent in the predetermined area to the wavelengths used for the refractive index measurement, wherein the prism structure (25′, 25″) provides surface sections that are angled with respect to the plate plane, at which incident light beams are refracted accordingly.