It is with great sadness that we learned of the passing away of dr. Ad P.J.M. de Jong on January 22, 2023 at the age of 75 years. Most of the Mass Spectrometrists do know him as a scientist that has pioneered Biomolecular Mass Spectrometry already in the early 1990’s, with a strong focus on developing nanoscale Liquid Chromatography. Many research groups have copied his nanoscale LC design and it is still used in many research institutes worldwide. He has had a many collaborations with a large number of research groups. Together with the Immunology group of Cécile van Els (from the National Institute of Public Health and the Environment, Bilthoven NL), he was frontrunner in the field of ImmunoProteomics. The NVMS spring meeting in 2013 at Intravacc (Bilthoven, NL), was dedicated to him because of his retirement.