After his retirement, he worked temporarily as a lecturer in the area of applied hygiene and medicinal products at the University of Albstadt-Sigmaringen.
After graduating in Biology and receiving a PhD in Biology, Microbiology and Chemistry, Hanfried Seyfarth joined Boehringer Ingelheim Pharma GmbH u. Co KG (previously Dr. Karl Thomae GmbH) in Biberach an der Riss in 1967 where he first worked in the Microbiology department. He served as Head of Microbiological Quality Control and held different managerial positions, including Expert for Microbiology at Boehringer Ingelheim.
Due to his extensive experience, he was appointed to a number of committees. These included the Microbial Purity working group at the Microbiology Committee of the German Pharmacopoeia Commission, the Group of Experts 1 (microbial impurities) of the European Pharmacopoeia Commission, and the Microbiology Committee of the German Pharmacopoeia Commission.
He is author or co-author of the following chapters of GMP Compliance Adviser: