[en] It has been demonstrated that formulation variables (pH, TcO₄^- concentration, and ligand-to-metal ratio) influence the chromatographic distribution of the components of a Tc-hydroxyethylidene diphosphonate (HEDP) mixture prepared by the NaBH₄ reduction of TcO₄^- in the presence of HEDP. The use of alternate reductants for TcO₄^- (i.e., SnCl₂, and electrode) not only alters the relative proportion of the Tc-HEDP components formed, but produces new complexes not previously seen (based on chromatographic retention time data). Thus, a systematic evaluation has been undertaken of the SnCl₂ and electrochemical reduction preparations that is similar to that conducted for Tc(NaBH₄)-HEDP mixtures. High performance liquid chromatography with electrochemical detection has been utilized to separate components of a Tc(NaBH4)-methylene diphosphonate mixture. All Tc components of the mixture are reducible at a mercury electrode and hydrodynamic voltammetric data is being generated. Stripping chronocoulometry has been developed as a novel variation of anodic stripping voltammetry in order to increase precision in the analytical determination of TcO₄^- in aqueous solution. Pilot studies to evaluate the operating parameters of ⁹⁹Mo//sup 99m/Tc/ generators and to investigate two new diphosphonate ligands in the preparation of technetium skeletal imaging radiopharmaceutical analogs have been initiated