Understanding the radiolabelling mechanism of 99mTc-antimony sulphide colloid.
The chemistry of antimony trisulphide colloid (ATC) was examined to elucidate the radiolabelling mechanism with 99mTcO4(-). Ion exchange chromatography and atomic absorption spectrophotometry techniques determined ATC to be resistant to hydrolysis in 0.1M hydrochloric acid (HCl) at 25 degrees C or 100 degrees C (>97% recovery, Sb3+ absent). Hydrogen sulphide gas detected did not participate in the mechanism, where antimony trisulphide and 99mTcO4(-) in HCl/100 degrees C yielded 96% 99mTc-product from a K2S-free formulation (versus 98% when K2S was present). 99mTcO4(-) was reduced >90% by DMSA or dithiothreitol under the same conditions, identifying involvement of thiol groups. Infrared analysis of Re-ATC showed S=O bonds, indicating excess thiol groups at the colloid surface were oxidised at the expense of 99mTcO4(-) reduction.
Tsopelas
Chris
C
RAH Radiopharmacy, Nuclear Medicine Department, Royal Adelaide Hospital, North Terrace, Adelaide 5000, Australia. ctsopela@mail.rah.sa.gov.au
D000965:Antimony / Q000737:chemistry; D007553:Isotope Labeling / Q000379:methods*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000737:chemistry; D013670:Sodium Pertechnetate Tc 99m / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D013667:Technetium / Q000737:chemistry; D013671:Technetium Tc 99m Sulfur Colloid / Q000138:chemical synthesis* / Q000737:chemistry
D019275:Radiopharmaceuticals; D013440:Sulfides; D013671:Technetium Tc 99m Sulfur Colloid; D013667:Technetium; D000965:Antimony; D013670:Sodium Pertechnetate Tc 99m; C064234:antimony trisulfide