Six new vibramicine.H[Cr(NCS)4(amine)2] type complex salts of the vibr
amicine (doxycycline) have been isolated from hydrochloric acid soluti
ons (amine = NH3, aromatic and heterocyclic amines). Some new gravimet
ric, oxydimetric (permanganometric, iodatometric) and spectrometric me
thods were described for the analytical determination of this antibiot
ic on the basis of complex salts, insolube in water and solube in acet
one. Results were statistically interpreted.