art by using molar ratios of lu hac between 130 1 and 100 1 for complexation yields of incorporation of lu ranging between 40 and 60 are obtained calculated on the basis of the moles of dota introduced per mg of hac used determined by a spectrophotometric method such yield calculated using samples that contained not less than 2 4 moles dota moles ha and not more than 4 moles dota moles ha example 1 corresponded to a range of incorporation between 20 and 26 nmoles of lu mg hac example 2 also this measurement allows to indirectly establish in addition to the efficiency of complexation in the labelling conditions the conjugation of p sch bn dota to ha furthermore it confirms that the conjugation product hac although no more soluble in aqueous phase is able to exert its typical metal complexing action characteristic of dota also in suspension i e a heterogeneous phase in the same way it was possible to demonstrate that hac exerts its complexing action towards metals also after freeze drying and reconstitution of the suspension from fig4 one can observe that freeze dried hac is present in the state of powder sample indicated with the c letter while freeze dried hap fig4 on the left is present with a markedly different aspect of flocky and light solid the product can be obtained in sterile form working in conditions of asepsis starting from medicinal preparations of ha thus certainly sterilized and apyrogen and using buffers and reagents wherein sterility is obtained through sterilizing filtration through.