Professor Determann is a member of supervisory boards of several family-owned companies. He was Chairman of the Board of Directors of the former Holding Company of Boehringer Mannheim Group, Corange Ltd. (Hamilton/Bermuda) until 1995.

In 1971, he joined Boehringer Mannheim GmbH as Director of Research & Development of the Biochemical Plant in Tutzing, Germany. He then became responsible for Product Planning, Research & Development, Production and Central Product Management for the Diagnostics and Biochemical Businesses in Germany, consecutively became "primus inter pares" of the German Management Board and in 1990 took global responsibility for Boehringer Mannheim Group as its President and CEO. In 1992, he left the Company. In 1994, upon shareholders' request, he rejoined the Board of Directors as Chairman.

From 1968 to 1971, Professor Determann was Scientific and Technical Director of BIOTEST-Serum-Institut GmbH in Frankfurt, Germany. Before that he was a Professor at the University of Frankfurt. He studied Chemistry and Biochemistry at the Universities of Heidelberg and Frankfurt.