A method detects metallic atoms in a fluid. The method includes: placing, in a zone sheltered from light, a photodiode comprising a photosensitive surface in contact with a fluid to analyze; heating the photosensitive surface of the photodiode to a temperature sufficient to allow metallic atoms deposited on the photosensitive surface to migrate through this surface; acquiring a signal relative to the lighting of the photodiode; and determining, from the acquired signal, a measurement representative of a contamination status by metallic atoms of the photodiode.