The resin-bound A-beta(3-40) amyloid peptide (I) is prepared by solid-phase synthesis, employing Fmoc chemistry. Acylation of the peptide-resin (I) with diethylenetriaminepentaacetic (DTPA) dianhydride (II) gives rise to the peptide DTPA-amide (III), which is further liberated from the resin to produce (IV)