The radiochemical purity of the three osteopatic ligands:99mTc(Sn)-PyP,99mTc(Sn)-DPD and99mTc(Sn)-MDP has been determined by gel chromatography on Sephadex. The results of the analyses strongly depend on the composition of the eluent. The dilution effect of pure saline as eluent was observed in all the preparations examined. The most sensitive was found to be99mTc(Sn)-PyP. The retention of99mTc activity bound to the gel matrix (99mTc-hydrolyte) was over 30%. The diphosphonates were found to be more stable (retention 10–15%). The retention is substantially lower, i.e. a high recovery of the labeled complexes is obtained when the eluent contains the ligand. The best results are obtained when the eluent contains the same concentrations of ligand and reductant as in the labeled complex. There was no significant difference in the behavior of the given radiopharmaceuticals prepared as a fresh solution and in the freeze-dried kit.
The effect of the preparation conditions on the in vitro stability of99mTc (Sn)-pyrophosphate kit solution has been examined. To extend the shelf-life of the preparation, different methods of protection were tested. Nitrogen purging stabilizes the kit for at least 6 h after labeling when the content of99mTc-pertechnetate raises to about 5%. However, this method is ineffective in the presence of hydrogen peroxide. The protecting ability of two chemicals was also determined. Gentisic acid gave good results. In the presence of 50 g of gentisic acid per ml of the kit the content of pertechnetate was 1–2% throughout the examined time interval. To eliminate the influence of hydrogen peroxide (6 g per ml of the kit) about 100 g of gentisic acid is needed. N, N-diphenyl-p-phenylenediamine (DPPD) performs some protecting effect only when used in the samples protected by nitrogen purging. However its protecting ability is lower that in the case of gentisic acid.
Gel chromatography of99mTc(Sn)-MDP on Sephadex has been performed by using the eluents of different composition and pH. Samples with constant ligand/reductant ratio were eluted by pure physiological saline as well as by saline which contained either the ligand only or both the ligand and the reductant. Their concentrations in the eluent were the same as those used in the preparation of the labeled complex.
The cold solution of a pyrophosphate kit was prepared and dispensed into 2-ml fractions which were stored at −20°C for one
week. The solution was prepared by using two protection methods. The first was nitrogen purging to exclude air and the second
one the addition of the well known antioxydant ascorbic acid. The aim was to determine the stability of99mTc(Sn)-PyP obtained by labeling these fractions prepared under the given experimental conditions. The content of99mTc-pertechnetate in the unprotected samples raises with time. Nitrogen purging provides some protection but already after
a few days the content of pertechnetate exceeds 5%. The addition of ascorbic acid gave good results. The content of pertechnetate
was 1–2% after seven days in the presence of 50 μg of acid per ml of the cold kit.
The in vitro stability of99mTc (Sn)-PyP as a function of experimental conditions of the preparation of the kit and time elapsed after labeling has been tested. The preparation was protected by using nitrogen-purged reactant solutions and kit vials and by ascorbic acid. The samples under nitrogen are stable for 6 h when the content of99mTc-pertechnetate raises to 5%. The best stability was achieved by addition of 5 g of ascorbic acid per ml of the kit (content of99mTc-pertechnetate about 0.5%). To accelerate the decomposition, exogenous hydrogen peroxide was used. In this case it was found that the presence of 10 g of ascorbic acid inhibits the effect both of oxygen and peroxide (6 g H2O2/ml of the kit). Radiochemical purity of99mTc (Sn)-PyP remains practically unchanged for 6 h (content of99mTc-pertechnetate about 0.5%).
Authors:J. Vučina, S. Milenković, and V. Šćepanović
The possible effects of several protecting procedures on the quality of99mTc eluates were investigated. The content of99Mo in the eluates (99Mo breakthrough) was expressed in (%) with respect to the total adsorbed99Mo radioactivity and in () i.e. as the ratio of99Mo and99mTc radioactivities in each particular eluate. The radiochemical purity was expressed in (%) of99mTc(VII) in the eluates. The content of Al3+ and Cu2+ as chemical impurities was also determined.
The separation of tungstate and perrhenate anions on alumina from aqueous solutions of sodium chloride was investigated in
dynamic conditions. The breakthrough curves for W and Re as the function of the ratio of their concentrations in the solution,
were determined. The flow rate (3 ml/min), pH 2 and NaCl concentration (0.15 mol/l) were kept constant throughout the experiments.
The breakthrough capacities Q0.05, the capacities at C/C0 = 0.5, the total column sorption capacities Q0.9 and the utilization degrees or column efficiencies E, were determined. According to the obtained data the separation factors αW/Re = Qw/QRe were calculated.
Authors:J. Vučina, Lj. Jaćimović, and S. Milenković
A modified sorbent for99mTe generators of higher activities has been developed. The sorbent consists of two layers. The layer in which (F.P.)99Mo is adsorbed contains alumina and silica gel mixture in the weight ratio 4060%. The underlaying layer contains 0.5% g of pure alumina. The performances of the columns filled with this sorbent are compared to these containing pure alumina with respect to the total elution efficiency of99mTc and the elution efficiency ratio of subsequent elutions. Radiochemical and radionuclidic purities (99Mo breakthrough) of eluates from both kinds of columns have also been determined and compared.
Authors:J. Vučina, V. Šćepanović, and R. Drašković
Some trace elements in samples from the aluminium industry (Aluminium Kombinat, Titograd, Yugoslavia) were determined by instrumental
neutron activation analysis. Samples characteristic for alumina production (bauxite, red sludge), reduction cell components
(alumina, anode, AlF3, cryolite) and aluminium produced (purity 99.5–99.7%) have been analyzed. 10 trace elements were determined under a given
set of working conditions and followed through the routine production.
Authors:J. Vučina, D. Vuga, and N. Vukićević-Nikolić
Some factors which could adversely affect the integrity of eight routine99mTc radiopharmaceuticals have been investigated. The radiochemical purity of the preparations was determined both under standard (reconstitution according to the manufacturer's instructions) and under experimental conditions (higher contents of longlived99Tc and copper). The influence of radiolytically produced hydrogen peroxide as well as the effect of introduction of air during the addition of pertechnetate as an example of poor labeling technique were examined. The radiochemical analyses were performed by paper and TL chromatography and electrophoresis.