The separation of Tc(VII) from Mo(VI) by thin-layer and paper-chromatography is discussed. Some aspects concerning the formation
and identification of lower oxidation states of Tc(VII) are also mentioned. Finally, a spot test is recommended for the determination
of Mo(VI) and Al, which can be contaminants in the Tc(VII) solution eluted from the99Mo column, filled with Al2O3.
The available six types of Sephadex and one type of Sepharose have been applied in the separation of technetium fractions in99mTc-labelled radiopharmaceuticals produced in our laboratory using the GCS technique. By this technique the chemical state and the percentage of99mTc-fractions have been determined. The resolution efficiency of some gel types were found to be significantly influenced by the pH of the eluent. The results obtained from the experiments indicated that Sephadex G-25 Fine was the best and can be routinely used in the radiochemical analysis of the following kits:99mTc-HSA,99mTc-DTPA and99mTc-HIDA and G-100 for99mTc-PYP. With99mTc-HSA and99mTc-PYP kits, 0.9% NaCl eluents at pH 3.2 and pH 2 to 2.5, respectively, were found to be necessary for the separation of99mTc-fractions. G-50 Fine was found to be the best gel between the others in the separation of99mTc-fractions in testing of the weak radiopharmaceuticals,99mTc-GH and99mTc-MDP. The development of99mTc-MDP with the eluent at the same pH as the preparation gives negligible interaction effect.
Authors:V. Jovanović, T. Maksin, M. Jovanović, J. Bzenić, and N. Terzić
The results obtained for radiochemical purity of ITLC (SA) and (SG) using different solvent systems and low voltage electrophoresis are presented in the paper. Radiochemical purities obtained for99mTc-dimethyl IDA (99mTc-HIDA) and99mTc-diethyl IDA (99mTc-EHIDA) are 98.1±0.6% and 98.7±0.5%, respectively. Variable99mTc hydrolyzate contents, depending on the ionic strength of the eluents and on the time interval between labelling and analysis, have been obtained by Sephadex chromatography. The eluent containing Sn-EHIDA inhibits dissociation of99mTc-EHIDA due to dilution of the preparation during elution of the column and yielding only a small percent of Sephadex bound fraction, as compared to other investigated eluents. The range of normal99mTc-IDA biodistribution values in the organs of experimental animals and statistical significance of the difference between these two preparations have also been determined. The results obtained for99mTc-HIDA and99mTc-EHIDA in the liver are 33.9±5% and 25.7±4.7%, respectively p<0.01.
Authors:S. Mirshojaei, M. Gandomkar, R. Najafi, S. Sadat Ebrahimi, M. Babaei, A. Shafiei, and M. Talebi
Cefotaxime, a cephalosporin antibiotic, used to treat bacterial infections was investigated to label with 99mTc. Labeling was performed using sodium dithionite as a reducing agent at 100 °C for 10 min and radiochemical analysis involved
ITLC and HPLC methods. The stability of labeled antibiotic was checked in the presence of human serum at 37 °C up to 24 h.
The maximum radiolabeling yield was 92 ± 2%. Bacterial binding assay was performed with S. aureus and the in vivo distribution was studied in mice. Images showed minimal accumulation in non-target tissues, with an average
target/non-target ratio of 2.89 ± 0.58.
Authors:Alireza Khorami-Moghadam, Amir Jalilian, Kamal Yavari, Bahram Bolouri, Ali Bahrami-Samani, and Mohammad Ghannadi-Maragheh
Antiangiogenic monoclonal antibodies in combination with therapeutic radionuclides are potential targeted therapy agents in
cancer. In this study, bevacizumab was successively labeled with [166Ho]HoCl3 after conjugation with DOTA-NHS-ester with a radiochemical purity of higher than 95% (RTLC). The conjugates were purified
by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined
by spectrophotometric method and the average chelate to antibody ratio (c/a) for the conjugate used in this study was 5.8:1
and protein integrity experiments (SDS-PAGE). The biodistribution studies in wild-type rats demonstrate a similar pattern
to the other radiolabeled anti-vascular endothelial growth factor A (VEGF-A) immunoconjugates. 166Ho-DOTA-bevacizumab is a potential compound for therapy/imaging of VEGF-A expression in oncology.
In the present work an improvement of radiochemical neutron activation analysis for determination of nanogram levels of vanadium is described. The method is based on post-irradiation wet ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine (BPHA) forming a violet chelate complex in strongly acidic medium. For quality assurance purposes a procedure for determination of the overall chemical yield using spectrophotometry of the V-BPHA complex is described, and possible interferences are evaluated. The procedure was applied to the determination of vanadium in reference materials and selected food samples from Slovenia.
Analysis of lichens and mosses were routinely performed by 17 laboratories from 15 countries around the world, participating
in a project coordinated by the International Atomic Energy Agency (IAEA). To improve and control the quality of such determinations,
the IAEA organized a two-round interlaboratory exercise, which allowed the detection and removal of most of the pitfalls observed
in the determination of 27 elements. The application of instrumental neutron activation analysis helped reveal poor recoveries
in some laboratories due to incomplete digestion for a number of elements. The exercise emphasized the importance of achieving
comparability of chemical measurements to a recognized reference.
Radioactive nuclides emitting b+-radiation are used for labeling in PET diagnostic. Before the radioactive labeled agent can be used, the radiochemical purity has to be determined by means of two separate radio-chromatography methods. For HPLC, TLC, GC and CE special radioactivity detectors sensitive for b+-radiation are required, which fulfil the regulations of various international and national authorities. All conventional chromatography detectors in applications of HPLC, TLC, GC and CE like UV-absorption, fluorescence, reflective index, conductivity, amperometry etc. have an analog signal output 0-1 V. Therefore all signal recording and peak integration systems for chromatography have analog inputs of 0-1 V.
Authors:T. Yassine, M. Bakir, S. Shanan, and M. AL-Asaad
Iodination of meta-iodobenzylguanidine was carried out at optimum conditions. The labeling yield at these conditions was more than 95%. Further purification of the prepared compound increased the radiochemical purity to more than of 99.5%, this high purity was revealed in the quality of the images resulting from the use of the prepared compounds.
The quality assessment of commercial soybean oils was evaluated on the basis of chemical and thermal analyses. The most substantial chemical parameters, viz. the density, refractive index and saponification, iodine and acid numbers were estimated. The thermal parameters were determined on the grounds of the TG and DTG curves. There are temperatures for the onset, end and successive mass losses. To find the relation between the chemical and thermal parameters, regression and principal component analyses were applied. The results of principal component analysis indicate that the TG and DTG techniques are at least in equal degree useful in defining the quality of soybean oils, as compared with the chemical analyses.