A simple and rapid method is described for the estimation of the radiochemical purity of [3H] stobadin. The proposed method uses the value of the partition coefficient /P/ as an indicator of radiochemical purity.
A simple and specific radiometric assay was developed for the determination of stobadine, a cardioprotective drug, in the
serum of experimental animals. The assay is based on a single extraction step of the radioactively labeled drug from serum
into the benzene solution of dicarbolide of cobalt followed by quantitation of the extracted radioactivity by using liquid
scintillation counting. The extraction mechanism involves the ion-pair formation between the protonized molecule of stobadine
and the hydrophobic, negatively charged molecule of dicarbolide of cobalt. The extraction yield of stobadine from 1 ml of
serum was 95% in the concentration range from 1 to 6000 ng/ml. The co-extraction of metabolites was less than 5%. The method
was applied to the determination of stobadine in serum of dogs and the data obtained were in a good agreement with those obtained
by high performance liquid chromatography.
The possibilities of extraction-chromatographic separation of137mBa from137Cs in genetic succession were studied, using columns filled with support beads loaded with the extractant H+[)–(3)–1,2–B9C2H11]2Co–, further referred to as dicarbolide-H+, in nitrobenzene. The dependence of the amount of separable activities on experimental conditions was established. Optimal conditions were selected for the separation process. The effects of isotopic and nonisotopic carriers of137mBa on the separation and the degree on saturation of extraction-chromatographic column with Ba2+ ions were evaluated. The effects of acidity of the elution solutions, of flow-through velocity, the amount of elution solution and the quality of carrier beads on the separation process were assessed. The extraction-chromatographic yield was calculated and the number of possible repeated elution cycles for137mBa with saline and some other eluents was determined.
Extraction by polyhedral complex compound of the formula H+ [(π-(3)-1,2-B9C2H11)2Co−] further on referred to as dicarbolide-H+ and its chloro-derivate H+[B18C4H15Cl7Co−] further on referred to as Cl-dicarbolide-H+ in nitrobenzene was used for the analysis of137Cs in urine and faeces after internal contamination. The dependence of distribution ratio on the acidity of analysed solutions
was determined. The effect of urine dilution was assessed as well as the effect of various concentrations of the extraction
agents on the distribution ratio of137Cs. The effect of phase ratio at the different concentrations of isotopic carrier was assessed, as well as the effect of potassium
ions on the decrease of the distribution ratio at the extraction of137Cs by dicarbolide-H+ or its chloro-derivate. The possibility of isolation of137Cs by extraction and the isolation of137Cs by ion-exchange absorbents and by ammonium molybdophosphate was compared. The values of distribution coefficient were determined
at various concentrations of nitric acid and the isotopic carrier. The dependence of coextraction of some activated radionuclides
and fission products by dicarbolide-H+ on the nitric acid concentration in the solute was determined. The effect of mass of contaminated faeces on the value of
the distribution ratio of137Cs by the extraction was evaluated. As a result, a suggestion was given for the rutine isolation procedure of137Cs extraction with dicarbolide-H+ from the excreta contaminated by a mixture of radionuclides.
The possibility of the use of chlorinated cobalt dicarbolide, H+C4B18H15Cl7Co−, it nitrobenzene for the selective extraction of137Cs from mixtures of95Zr−95Nb,106Ru-106Rh and144Ce was studied. The effect of aqueous phase acidity on the distribution ratio of Cs, Ru and Zr as well as the effect of the
amount of isotopic and non-isotopic carriers of alkali metals on the distribution ratio were determined. Separation factors
for cesium from ruthenium, zirconium and cerium were calculated, all being extracted from nitric acid solutions. The efficiency
of cesium separation was verified by gamma-spectrometry.
The possibilities of radiostrontium extraction from milk after the isolation of radiocesium were investigated. The polyhedral
complex of the type H+[(π-/3/-1,2-C2B9H11)2Co−], further referred to as dicarbolide-H+, in nitrobenzene was used for the extraction. The increase of values and larger differentiation of distribution ratios in
the extraction of ion associates of radionuclides were achieved by hydrophobizing with polyethyleneglycol (PEG). The changes
of the distribution ratios of90Sr,89Sr and90Y with PEG concentration were studied, and ranges of the highest synergic effect, changing with different extraction agent
concentrations in extraction from water solutions and a fresh milk were determined. The influence of milk dilution and nitric
acid concentration upon the value of distribution ratio in radiostrontium extraction using dicarbolide-H+ and the optimum PEG concentration were investigated. Under suitably selected conditions of radiostrontium isolation, the
distribution ratios of some potential contaminants were determined. The influence of nonisotopic carrier Ca2+ upon radiostrontium extraction was examined. The possibilities of purification of isolated radiostrontium using reextraction
were investigated. A selective and quick analytical procedure was suggested for radiostrontium isolation after the separation
of radiocesium from a mixture of fission and activated radionuclides in milk using extraction by dicarbolide-H+. The chemical yield is about 98% and90Sr is determined by liquid scintillation technique.
A simple and rapid radiochemical method for the efficient and selective isolation of3H-stobadine from plasma, urine and organ homogenates has been developed. The method comprises the extraction of3H-stobadine from the biological matrix containing 2M Na2CO3 into n-hexane followed by scrubbing of partly coextracted metabolites into an equal volume of 2M Na2CO3. The specificity of the procedure presented is demonstrated by TLC and the comparison of distribution coefficients of authentic and apparent (isolated) substances.
The distribution of some radionuclides in the course of137Cs and90Sr extraction and scrubbing between organic and water phase was determined.137Cs and90Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate]
was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique.
Single and repeated extraction of90Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO3 were studied. The extraction of90Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of137Cs followed by the extraction of90Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates
of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.
Authors:V. Ščasnár, Š. Bezek, T. Trnovec, R. Grupe, and I. Lissé
Cytostasan, 5-[Bis(2-chloroethyl)amino]-1-methylbenzimidazolyl-2-butyric acid, is an antineoplastic agent which degrades spontaneously in water solutions yielding two hydrolysis products, monohydroxy- and dihydroxycytostasan. We developed a stability-indicating radiochemical assay based on ion-pair extraction to investigate the stability of solutions of14C-cytostasan under conditions that might be expected when the drug is being prepared and stored for pharmacokinetic studies in animals. The possibility of using the distribution coefficient of14C-cytostasan as an indicator of stability was investigated in the extraction system benzene-dicarbolide of cobalt-0.5N HClO4. The mechanism of extraction is believed to be that of ion-pair forming process between the hydrophobic anion and the protonized cytostasan. Since no extraction of hydroxy derivates was observed the value of the distribution coefficient of the parent drug appears to be a suitable indicator of the stability of14C-cytostasan solutions.
Authors:V. Ščasnár, M. Štefek, Š. Bezek, and L. Beneš
Pentacaine, heptacaine and carbisocaine, new local anaesthetics of Czechoslovak origin, are weak bases of the carbanilate type. Their pKA values are 8.6, 8.9 and 8.8, respectively. The technique of ion-pair extraction was found to be more effective than usual access using the extraction of nonionized species. The counter-ion ClO4 was chosen as the most efficient. The extraction yield of pentacaine into benzene from strongly acidic media (IN HClO4) of biological matrix after subsequent scrubbing of coextracted metabolites into a buffer of pH 9.6 is over 90%. The radiochemical purity is better than 92%.