SEPARATION AND CHARACTERIZATION OF TECHNETIUM HYDROXYETHYLIDENE DIPHOSPHONATE AND TECHNETIUM FORMATE COMPLEXES (RADIOPHARMACEUTICALS, CHROMATOGRAPHY, PREPARATION, SPECTROSCOPY)
Abstract
The preparation and separation of tin reduced technetium hydroxy-ethylidene complexes (Tc-HEDP Sn ) have been studied. A Tc-HEDP Sn mixture has been prepared using millimolar pertechnetate to act as an analog of Tc-HEDP Sn radiopharmaceuticals. An anion-exchange HPLC separation has been developed for this mixture which resolved 5 predominant components and 13 additional minor complexes. A precolumn backflush technique was developed to protect the analytical column from unreacted pertechnetate. The product distribution obtained was found to depend upon the reaction pH. The individual complexes were found not to be stable upon isolation from the mixture and appear to react to form other complexes in the mixture. Spectral characterization of the Tc-HEDP Sn complexes was attempted. UV-vis spectra of the complexes were obtained using an on-line diode array spectrophotometer. Raman spectra of the complexes indicated the presence of O=Tc=O and Tc=O cores. Mass spectra of Tc-HEDP Sn complexes could not be obtained, but were obtained of the ligand-reductant solution indicating species with the general formula of Sn(,x)-(HEDP)(,y) where x and y = 1 to 4. Determination of the ligand-to-metal ratio of selected Tc-HEDP complexes was attempted using ('14)C labeled HEDP and ('99)Tc. The results were inconclusive because of low labeling efficiency of the ('14)C-HEDP. It was determined that ('32)P is the isotope of choice for labeling HEDP. Sodium borohydride and tin reduced Tc-HEDP mixtures were compared using anion-exchange HPLC and UV-vis spectrophotometry. It was found that the two mixtures contain the same complexes. It was further shown that tin is incorporated into only one minor component of the Tc-HEDP Sn mixture and that the use of carrier added and no carrier added pertechnetate concentrations lead to the formation of the same complexes, but with different distributions. The preparation, separation, and characterization of a Tc-formate mixture proposed as a ligand-exchange precursor was investigated. Preparation using Sn, NaBH(,4), and electrochemical reductants produced the same species, separation was achieved using anion-exchange HPLC, and characterization was attempted using UV-vis and infrared spectrophotometry. The Tc-formate mixture was observed to react with several nitrogenous ligands, forming several products.
Degree
Ph.D.
Subject Area
Pharmacology
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