0000000000299881
AUTHOR
J. Galvez Alvarez
Prediction of the chemiluminescent behavior of pharmaceuticals and pesticides.
The present paper deals with the first attempt to apply molecular connectivity calculations to predict a chemical property with analytical usefulness: the chemiluminescent behavior of substances when reacted with common oxidants in a liquid phase. Preliminary evidence when searching for new direct CL methods consisted of the examination of analyte reaction with a wide range of oxidants and media. This task, which results in time-consuming and trial-and-error expensive procedures, is necessary due to ensure empirical or theoretical rules for CL prediction are available. On the other hand, in quantitative structure-activity relationship studies, molecular connectivity is a topological method …
Some aspects related to stability, critical concentrations and kinetics of flocculation of the calcium phytate colloid
Abstract As 99mTcCa phytate is an important radiopharmaceutical and its colloidal nature presents problems, we investigated some of them. This work describes the study of the colloidal behaviour of the calcium phytate colloid in terms of its formation, stability and kinetics of flocculation. The study of spontaneous, and centrifugation-induced flocculation allows the determination of two critical concentrations of sol flocculation. The titrations of calcium phytate colloid at different concentrations provide information on the colloidal formation conditions. Moreover, a study on flocculation kinetics was made by turbidity measurements.
Physico-chemical study of the radiopharmaceuticals 99mTc-DMSA, 99mTc-EDTA and 99mTc-DTPA interaction with plasmatic proteins.
This report studies the binding rate of the radiopharmaceuticals 99mTc-DTPA, 99mTc-EDTA and 99mTc-DMSA to plasmatic proteins. The proteins bind to the tested radiopharmaceuticals in the following sequence: 99mTc-DTPA less than 99mTc-DMSA(C1) less than 99mTc-EDTA less than 99mTc-DMSA(C2) where C1 and C2 represent two different Tc-DMSA complexes. The thermodynamic study suggests a quantitative relationship of radiopharmaceutical:protein = 1:1 and an almost nonexistent influence of the temperature, which means that the interacting forces in this process are relatively weak.
Stability of the radiopharmaceutical []DMSA: Study of the ligand exchange reaction with [99Tc]EDTA
Abstract A kinetic study was made of the ligand exchange reaction between [ 99 m Tc]EDTA and DMSA. The results of this study indicate that this exchange reaction is closely related to temperature and pH. Kinetic and thermodynamic parameters demonstrate that both complexes—[ 99 m Tc]EDTA and [ 99 m Tc]DMSA—have a similar stability. Furthermore, the existence of an acid-basic catalysis for the global exchange reaction was established, and the catalytic parameters were calculated. These data were obtained by radiochromatography and visible spectrophotometry.
Molecular topology and chromatographic retention parameters for benzodiazepines
Abstract The relationship between gas-liquid chromatographic (GLC) retention properties and R F values in thin-layer chromatography (TLC) with molecular connectivity indices, m X t , was investigated for a series of benzodiazepines using multiple correlation coefficients, standard errors of estimate, F -Snedecor function values and Student's t -test as the criteria for best equation selection. Regression analyses show that the molecular connectivity model predicts the retention properties in GLC with the polar stationary phase OV-17 at 280°C and the R F values in TLC with the stationary phase silica gel. However, zero- or second-order connectivity indices alone are not sufficient; higher-or…
[99mTc]Ca-Phytate: Some colloidal characteristics related to the optimal preparation conditions
Abstract Some physico-chemical characteristics of the colloidal radiopharmaceutical [ 99 m Tc]Ca-phytate related to optimal preparation conditions have been studied. (1,2) It is demonstrated that the Ca 2+ -phytate stoichiometry is 6:1. Two different Ca-phytate colloids seem to be formed, mainly depending on the Ca 2+ :phytate molar ratio-one of low mycelar size for a 1:1 Ca 2+ :phytate molar ratio ( cmc ∗ = 5.10 −5 M ) , and another one, with a higher mycelar size for a 6:1 molar ratio (cmc = 8.10 −5 M). This last one it probably better for providing a good quality splenic uptake.