Improved labelling of DTPA- and DOTA-conjugated peptides and antibodies with 111In in HEPES and MES buffer

EJNMMI Research

Table 1 Maximal specific activities of DTPA- and DOTA-conjugated compounds

Compound	NaAc (MBq/nmol)^a	NH₄Ac (MBq/nmol)^a	MES (MBq/nmol)^a	HEPES (MBq/nmol)^a	Maximum theoretical SA^b (GBq/nmol)
DTPA-exendin-3	379 ± 16	207 ± 20	717 ± 29	837 ± 6	1.7
DTPA-octreotide	95 ± 5	52 ± 4	248 ± 24	650 ± 10	1.7
DTPA-cG250	338 ± 60	246 ± 37	835 ± 46	939 ± 50	5.2
DOTA-exendin-3	23 ± 8	22 ± 1	56 ± 4	38 ± 16	1.7
DOTA-octreotide	38 ± 0	39 ± 0	39 ± 0	39 ± 0	1.7
DOTA-cG250	330 ± 87	254 ± 2	947 ± 44	1018 ± 7	12.4

^aMaximal specific activities (in megabecquerel per nanomole) and the ^bmaximum theoretical SA (in gigabecquerel per nanomole) for DTPA-exendin-3, DOTA-exendin-3, DTPA-octreotide, DOTA-octreotide, DTPA-anti-CAIX and DOTA-anti-CAIX in 0.1-M NaAc, NH₄Ac, MES and HEPES buffers. The maximum theoretical SA is calculated, assuming that 1 nmol DTPA or DOTA can complex 1 nmol ¹¹¹In.