Formation of 99mTc-plasmin in presence of gentisic acid using 99mTc pretreated with concentrated hydrochloric acid and vacuum evaporation.

The concentrated hydrochloric acid/vacuum evaporation method has been applied to form 99mTc-plasmin complexes free from radiocolloids for medical scintigraphy. The yield and radiochemical purity were insufficient for medical application when no antioxidant was present during the complex formation. With gentisic acid present the yield was increased by a factory of 2-3, and high radiochemical purity was obtained. No preparative chromatography was necessary. Presence of ascorbic acid inhibited the 99mTc-plasmin formation.