RADIOCHEMICAL IMPURITIES IN 99mTc
RADIOPHARMACEUTICALS
Free Tc Chemical form: Pertechnetate, TcO4
Hydrolyzed Reduced Tc Chemical form is probably 
TcO(OH)2.H2O, a hydrated Tc-oxide
99mTc MAG3 Possible impurity is 99mTc tartrate
99mTc HMPAO Stereochemical impurities

THIN LAYER CHROMATOGRAPHY SYSTEMS
OF Tc-99m COMPOUNDS

Tc-99m DTPA, MDP, GH, PYP, HDP, MAA, MIAA, SC
SYSTEM IMPURITY MEASURED
Silica Gel/0.9% saline Hydrolyzed Reduced Tc
Paper/acetone or paper/MEK Free Tc (Pertechnetate)

Tc-99m CHROMATOGRAPHY:
SEPARATION ON STRIP
SYSTEM SEPARATION OF RADIOCHEMICAL SPECIES
Silica Gel/saline HR Tc in bottom half;
all other species in top half
Paper/acetone or 
paper /MEK		 Free Tc in top half; all other species in bottom half.
ITLC-SA/20% saline HR Tc in bottom half; all other species in top half
ITLC-SG/water Free Tc in top half; all other species in bottom half

THIN LAYER CHROMATOGRAPHY SYSTEMS
Tc-99m HEPATOBILIARY AGENTS
SYSTEM IMPURITY MEASURED
ITLC-SA/20%saline Free Tc (Pertechnetate)
ITLC-SG/water Hydrolyzed Reduced Tc

EXCEPTION TO THE RULE

For insoluble Tc-99m Radiopharmaceuticals (e.g., Tc-MAA, Tc-SC), it is only necessary to test for the presence of free Tc. No simple system can effectively separate colloidal HR Tc from an insoluble product, so HR Tc cannot be measured in these products. We therefore ignore its presence.