Abstract: A device for the qualitative and/or quantitative determination of the composition of a sample to be analyzed. The device includes at least one hollow body which is coated on the inside with an optically reflecting material or is composed completely of an optically reflecting material, and which is provided with at least one aperture. At least one radiation detector is provided proximate to the hollow body in the interior of the hollow body or in the vicinity of the hollow body. At least one ATR (Attenuated Total Reflection) element covers the at least one aperture of the hollow body, and the sample which is to be analyzed is disposed at the side of the ATR element turned away from the hollow body. At least one primary radiation source provides radiation which is received by the ATR element without directly entering the hollow body.