Improvement of iodide and iodate identification method in the radiochemical analysis of Iodine-131 radiopharmaceutical
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EJNMMI Radiopharmacy and Chemistry
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Aim: Sodium Iodide (131 I) is a radiopharmaceutical available as oral
capsule or solution, and is largely used in nuclear medicine for tyroid
scintigraphy imaging and in radioiodine therapy. Radiochemical purity
(% RqP) is defined as the percent of total radioactivity in the desired
chemical form. The main methods to determine % RqP is paper
chromatography (PC), thin-layer chromatography (TLC) and high perfomance
liquid chromatography (HPLC). Some compendial methods
also establish procedures for retardation factor (Rf) determination1-2.
The objective of this work was to evaluate the mobile phase effect
on the Rf of iodide (I-) and iodate (IO3
-) in the % RqP analysis of Sodium
Iodide (131 I). Methods: Whatman 3MM PC (1.5 × 12.5 cm), methanol and glacial
acetic acid were from Merck Millipore. Methanol and purified water
in the proportion of 50%, 70%, 75% and 85% (v/v) were the mobile
phases. Diluent solution containing 0.1 mg/mL KIO3, 0.2 mg/mL KI
and 1.0 g/mL Na2CO3, and standard solutions of 0.2 g/mL KI and 0.4
g/mL KIO3 were prepared. In the origin position of a 10 cm paper
strip, 5 μL of the diluent solution were applied. After chromatographic
separation in each mobile phase, the suitable standard solution
was dripped on the iodate and iodide expected positions
followed by drops of glacial acetic acid to reveal the Rf of the species
with formation of a brown spot3.
Results: The American and Argentine pharmacopoeial methods
present iodate-131 as the main radiochemical impurity but differ in
the mobile phase composition and in the color development method
for iodide and/or iodate1-2. The systems advocate the use of 30 and
20 cm long stationary phases which require several hours for separation
of the species, and methanol 70% and 75% (v/v), respectively.
In a 10 cm strip and 70% (v/v) methanol, the Rf for iodate was 0.5-0.7
and for iodide was 0.7-0.9; with 85% (v/v) methanol, the Rf were 0.3-
0.5 for iodate and 0.7-1.0 for iodide, respectively, taking an hour and
a half for the chromatografic run. The resolution obtained with 85%
(v/v) methanol was better when compared to methanol 70% (v/v).
Conclusion: By the use of the staining test for iodate and iodide proposed
by the Argentine pharmacopoeia, it was possible to improve
the % RqP analysis of Sodium Iodide (131 I), decreasing the analysis
time of more than 4 hours to an hour and a half.
Como referenciar
FURUKAWA, C.Y.; MENDONCA, V.; FUKUMORI, N.T.O.; MATSUDA, M.M.N. Improvement of iodide and iodate identification method in the radiochemical analysis of Iodine-131 radiopharmaceutical. EJNMMI Radiopharmacy and Chemistry, v. 3, n. 7, p. 25-25, 2018. 1. DOI: 10.1186/s41181-018-0041-4. Disponível em: http://repositorio.ipen.br/handle/123456789/29130. Acesso em: 26 Apr 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.