ABSTRACT
The use of a non-volatile modifier and the simultaneous exclusion of oxygen by flushing with helium in ion-pair HPLC of 99mTc(Sn)EHDP-complexes prevents spurious oxidation during the separation process. It thus enables the omission of the reducing agent from the eluent solution and the determination of the labelling percentage from the TcO4(1)-peak. In addition, retention times become more reproducible.
Subject(s)
Etidronic Acid/isolation & purification , Organometallic Compounds/isolation & purification , Organotechnetium Compounds , Technetium/isolation & purification , Tin , Chromatography, High Pressure Liquid/methodsABSTRACT
99mTc(Sn)-EHDP complexes have been produced by reduction of TcO4- with Sn(II) in the presence of EHDP at varying pH and EHDP concentration. The mixture was separated by means of gel-chromatography with an eluent of the same composition and pH as the reaction mixture. It appears that at neutral pH larger complexes are formed than under acidic or basic reaction conditions. Larger complexes are also formed at higher EHDP concentrations.
Subject(s)
Bone and Bones/diagnostic imaging , Etidronic Acid , Organometallic Compounds , Organotechnetium Compounds , Chromatography, Gel/methods , Etidronic Acid/isolation & purification , Humans , Hydrogen-Ion Concentration , Organometallic Compounds/isolation & purification , Radionuclide ImagingABSTRACT
For the characterization of the multi-component bone-scan agent 99mTc(Sn)EHDP we have analysed the complex mixture with reversed phase ion pair chromatography (IPC) and soft gel permeation chromatography (GPC). With IPC five major complexes were found within a separation-time of 40 min. To avoid decomposition of the complexes during separation, the concentrations of EHDP and the reductant Sn(II) in the eluent had to be identical to the EHDP and Sn(II) concentrations used for the preparation of the complexes. To investigate the stability of the complexes we applied separation by IPC, followed by re-analysis of the fractions within 1 h and after 21-25 h. It appears that there is a state of equilibrium between the five complexes. Within 1 h after isolation the separated complexes were still more than 90% in their original form while after 20 h considerable amounts of the other complexes are found. The two complexes with the largest retention time with IPC are the most stable ones. When the total mixture was re-analysed after 26 h all five components appeared to be still present, but the relative amount of the most stable component had increased. Using GPC for the separation of the complex mixture, we found four major peaks within a separation time of 14 h. The elution orders of the complexes with the two separation methods are opposite.
Subject(s)
Etidronic Acid/isolation & purification , Organotechnetium Compounds , Technetium/isolation & purification , Bone and Bones/diagnostic imaging , Chromatography, Gel , Chromatography, High Pressure Liquid , Humans , Radionuclide ImagingABSTRACT
Anion exchange high performance liquid chromatography has been utilized to separate the component Tc-HEDP complexes of "carrier added" as well as "no carrier added" 99mTc(NaBH4)-HEDP reaction mixtures. The chromatographically separated "carrier added" Tc-HEDP components exhibit distinctly different biodistributions which are directly related to the chromatographic characteristics of the individual components. The Tc-HEDP complexes with shortest retention times, and therefore the lowest negative "charge density" have the maximum uptake on the bone, minimum uptake in the kidney, and fastest blood clearance.
