New biomolecule-labelling agents such as biotin-vinyl sulfone, which allows the biotinylation of proteins, and fluorophore (fluoresceine, rhodamine, dansyl)-vinyl sulfone, which allows the fluorescence labelling of biomolecule, have been synthesised These agents also include ferrocene-vinyl sulfone, which allows biomolecules to be labelled with electroactive labels, and biotin-fluorophore-vinyl sulfone, which allows a double labelling to be performed simultaneously