Metal-organic allergens on surfaces of objects of daily use, such as jewelry or coins, are of increasing relevance in multiple dermatologic problems. The chemistry behind the formation and reaction of metal-associated allergens is widely unexplored. Complexes of nickel, copper and tin are known to be easily formed through contact of metal alloys with ubiquitous organic compounds from, e.g., skin secretions. The project aims to investigate the structure, occurence, and reactivity of typical organic reactants and of formed metal complexes on the three-dimensional surface of jewelry, decoration and coins, using atmopsheric-pressure matrix-assisted laser desorption/ionization mass spectrometry. The influence of topographic effects shall be described by the use of 3D-surface mass spectrometry imaging techniques on the micrometer scale, uniquely available at the Giessen labs. The chemistry of complex formation will be studied in vitro by organometallic synthesis, and their spontaneous formation on real objects will be simulated.