The control of analytical data by randomly inserted standards or reference materials is quantified in terms of elementary statistics. The consequences of a given number of standard aliquots are interpreted on the basis of the a priori expectation on the average defective fraction. It appears that, in most cases, standards serve to detect sudden large errors only. Some practical examples are considered.
Lanreotide, a synthetic octapeptide analog of a native hormone somatostatin, was labeled with 131I, the most widely used therapeutic and easily available radionuclide. Radioiodination of Lanreotide was carried out by Chloramine-T
and Iodogen methods. Chloramine-T and Iodogen were used as oxidizing agents to form an electrophilic iodine species, which
then labeled the tyrosine of Lanreotide. The maximum radiolabeling yield was ~80%. Chloramine-T was found more suitable than
the Iodogen method, because nearly 25% of the initial iodine activity was lost/adsorbed on the Iodogen coating. Thin layer
and high performance liquid chromatographies were used for monitoring the reaction of 131I with Lanreotide, the stability and purity of 131I-Lanreotide.
Authors:S. Achando, J. Osso Junior, and N. de Pereira
A rapid, miniaturized chromatography system has been developed to determine the possible contaminants of67Ga-citrate. This method is simple, inexpensive and suitable for laboratory routine tests. By classical paper chromatography the analysis takes several hours to complete.
Authors:E. Gattavecchia, D. Tonelli, A. Breccia, A. Fini, and E. Ferri
Radio TLC has been used for determining the radiochemical purity and composition of two99mTc-radiopharmaceuticals, available as kits and commonly used for diagnostic imaging. Moreover, the same technique has been applied to detect impurities which decrease the specific activity of131I-derivatized dermatan sulfate, a new potential radiopharmaceutical, and for establishing the best labeling conditions.
Authors:B. Van Gansbeke, O. Jeghers, and A. Ermans
Paper and TLC chromatographic methods have been evaluated for the control of the labeling and stability of eight Tc-radiopharmaceuticals. The different supporting media and eluents have been studied and the most suitable methods have been classified according to their usefulness, reliability and rapidity. Moreover the artefacts encountered have been investigated. Alumina is found not suitable for its interference with TcO
. Acetate buffer seems to be labeled by TcHR inducing frequently subsequent smearings. Methyl ethyl ketone is optimal for the quantification of TcO
except in Tc-HIDA. TcHR never migrates as well as Tc-S Coll, Tc-MAA and Tc-HSA. The well-defined separation of TcO
and TcHR from the radiopharmaceutical often requires a two-step method.
Cefuroxime axetil, a cephalosporin antibiotic used to treat bacterial infections, was investigated to label with 99mTc. Radiolabeling of cefuroxime axetil was carried out by using stannous chloride method. Effects of pH and stannous chloride
amount on the radiolabeling yield were investigated. The radiochemical purity of 99mTc-cefuroxime axetil was determined by thin layer radio chromatography (TLRC), electrophoresis and high performance liquid
chromatography. The maximum radiolabeling yield was 98±1%.
Authors:S. Roohi, A. Mushtaq, M. Jehangir, and S. A. Malik
Kanamycin is an antibiotic used for treatment of infections when penicillin or other less toxic drugs cannot be used. Kanamycin
was labeled with technetium-99m pertechnetate using SnCl2. 2H2O as reducing agent. The labeling efficiency depends on the ligand/reductant ratio, pH, and volume of reaction mixture. Radiochemical
purity and stability of 99mTc-Kanamycin was determined by thin layer chromatography. Biodistribution studies of 99mTc-Kanamycin were performed in rats and rabbits. A significantly higher accumulation of 99mTc-Kanamycin was seen at sites of S. aureusinfected animals (rat/rabbit).
Authors:V. Jovanović, T. Maksin, D. Konstantinovska, B. Zmbova, and J. Čvorić
Two methods for the determination of radiochemical purity of preparations labeled with99mTc are described. Paper chromatography was used for separation of reduced99mTc and free pertechnetate from the labeled radiopharmaceutical. Whatman 3MM paper was used first with a acetone and then with
1N NaCl, as the mobile phase. Instant thin layer chromatography was performed for comparison. The electrophoretic method was
also applied, using 0.05 M Na-acetate and 0.017 M NaCl. Biodistribution of99mTc-DMSA in the organs of experimental animals was followed in order to verify chemical control methods.