Boron, germanium and the halogens: these elements were the focus of Annelore Köster-Pflugmacher’s research. As a professor of chemistry at RWTH Aachen University, she also undertook extensive teaching duties.

Annelore Köster-Pflugmacher (née Trapp) was born on 19 March 1919 in Königsberg, East Prussia (now Kaliningrad, Russia). After completing her A-levels, she studied chemistry at the Albertus University in Königsberg. She completed her doctoral thesis on silicon iodide under the supervision of Robert Schwarz (1887–1963) at the university’s Institute of Inorganic Chemistry. On 21 November 1942, she was awarded a ‘Doctor of Natural Sciences’ degree.

During her studies, she met Dieter Pflugmacher, whom she married in 1941. However, the Second World War left her a widow within a short time. Her husband was killed in action in July 1943.

From July 1942 to November 1944, Pflugmacher worked as a research assistant at the Department of Chemistry at the University of Königsberg. Shortly before the advance of Russian troops, she fled to the West in 1945. Pflugmacher eventually found a new professional home in Aachen. She had followed her doctoral supervisor, who in 1948 had accepted a post at the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen as a full professor of inorganic chemistry and electrochemistry. In April 1950, Pflugmacher was appointed to a permanent post as a research assistant at the RWTH, where she submitted her habilitation thesis in 1953, entitled ‘On the Nature of Bromine Oxides’. In 1960, she was appointed to an extraordinary professorship and, in 1961, became a Senior Research Fellow at the RWTH. During this time, she met the chemist Alfred Köster, whom she married in 1962. Two years later, the couple moved to Langenfeld in the Rhineland.

In her research, Köster-Pflugmacher focused on the oxides of bromine and the halides of boron, as well as on the organometallic compounds of germanium. She primarily used X-ray fluorescence spectroscopy as her analytical method. At RWTH, she also undertook extensive teaching duties, as her remit included providing chemistry training for students of mechanical engineering and other disciplines. In addition, she supervised the chemistry lectures for trainee teachers. From 1961 onwards, Köster-Pflugmacher was also the editor of the German-language new editions of the textbook *Qualitative Schnellanalyse der Kationen und Anionen* by Gaston Charlot (1904–1994), the founder of modern analytical chemistry in France.

In March 1981, Köster-Pflugmacher retired. In 2010, RWTH Aachen University honoured her habilitation thesis in the calendar “100 Years of Women’s Studies at RWTH”. Annelore Köster-Pflugmacher lived to the age of 83 and resided in Langenfeld until her death. She passed away on 12 August 2002.

Sources
H. Werner: History of Inorganic Chemistry, Wiley & Sons, Weinheim, 2016, p. 158

Memorial of RWTH Aachen, Alma Mater Aquensis, Special Edition 1870–1995, p. 71