Abstract: The invention relates to an apparatus for the inline trace analysis of a liquid, preferably of an aqueous process solution, comprising: a housing (1); a micro-channel (2) through which the liquid to be examined is allowed to flow and into which light of a light source (3) is coupled; a detector (4) for light emerging from the micro-channel (2); and a user interface (5) for monitoring and/or operating the apparatus. The micro-channel (2), the detector (4) and/or the user interface (5) are arranged in the housing (1) and/or are integrated into the housing (1), and the housing (1) has a connection (6) for feeding the liquid in the micro-channel (2) and a connection (7) for power supply of the apparatus.