A microfluidic arrangement (1) for the optical detection of fluids is provided, comprising a microfluidic device (2) having at least one first channel (3) with an opening (4) which is in fluid communication with an optical detection unit (6) of an optical device (5); the microfluidic device (2) being operatively detachably coupled with the optical device (5) whereby an extension of the part (7,7′) of relevance of the optical detection path (17) is provided. A method for detecting fluids using the arrangement of the present invention is provided.