Chemistry and Isotopes of Iodine
Erwin Regoeczi in Iodine-Labeled Plasma Proteins, 2019
The parameter to be established by paper chromatography is the retardation factor of a compound, commonly known as the Rf value. The Rf value is the mobility of a compound relative to that of the solvent front expressed as a fraction. For example, if the solvent front has moved 140 mm and the compound 70 mm, the Rf value is 0.5. For a given solvent system, the Rf is a characteristic of the compound, and it may be used, with precautions, for the preliminary identification of an unknown substance. The Rf values of many compunds are available in tables.31'32 Reproducibility of Rf values depends on the constancy of the following seven factors:35 paper, temperature, quantity of material applied, extraneous sub-stances, degree of saturation with water, supply of solvent, and distance between starting point and source of solvent.
Mathematical models of intraperitoneal drug delivery
Wim P. Ceelen, Edward A. Levine in Intraperitoneal Cancer Therapy, 2015
Note that changes in the tissue hydration may influence diffusive properties of the solute in the tissue, so in general, DS should be considered as θ or P dependent. Moreover, in some applications, parameter is called the sieving coefficient or the retardation factor as it represents the ratio of solute to solvent velocity, and in applications to solid tumor, is typically assumed to be equal to 1.
Current Perspectives and Methods for the Characterization of Natural Medicines
Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg in Promising Drug Molecules of Natural Origin, 2020
Thin-layer chromatography is used for the characterization of natural compounds by a qualitative and quantitative manner. The major principles of thin-layer chromatography are adsorption or partition or both depending upon the adsorbent (stationary phase) and solvent (mobile phase). Silica gel, alumina, cellulose powder, kieselguhr, and Sephadex gel are used as the stationary phase. The mobile phase is carbon tetrachloride, benzene, ethyl acetate, dichloromethane, hexane, chloroform, ethanol, and water. The chemical components having an efficient affinity to stationary phase travel slower, whereas the components with a lower affinity toward the stationary phase travel faster. A stationary phase is used as a silica gel coated strip and organic solvents are play as mobile phases. The adsorbent is loaded on thin glass/sheet/plastic and it acts as a stable phase. About ~25 mm thickness coating on the glass plate was used for thin-layer chromatography. Plaster of Paris is used as a binder to makes coating of adsorbent. After the preparation of plates, all the plates are activated by keeping it in 100ºC for 3 hr. The organic solvent are spotted at the bottom of the stationary phase. The solvent or mixture of solvent is allowed to move up to the plate by capillary action. The compounds are separated with respect to its affinity, size, and charge. Retardation factor (Rf) value (distance traveled by solute/distance traveled by solvent front) is used as a characteristic parameter in thin-layer chromatography. However, the nature of adsorbent, mobile phase, the thickness of layer, temperature, and sample loading are the critical factors and it can alter the Rf value. Thin-layer chromatography separates the components into the individual by using a finely divided adsorbent (solid/liquid) spread over a plate. The technique is employed under temperature and pressure-controlled laboratory. Thin-layer chromatography provides many advantages over other chromatography, i.e., (i) non-volatile/low volatile chemical compounds able to analyzed; (ii).
Sauromatum guttatum extract promotes wound healing and tissue regeneration in a burn mouse model via up-regulation of growth factors
Published in Pharmaceutical Biology, 2019
Ali Said, Fazli Wahid, Kashif Bashir, Hafiz Majid Rasheed, Taous Khan, Zohaib Hussain, Sami Siraj
TLC analysis was performed to further confirm the presence of various major phytochemicals in the crude extract. TLC plates (Merck) pre-coated with silica gel (60 F254) were used as stationary phase, while methanol-chloroform (8:2 v/v) was used as mobile phase. TLC plate was developed in the above mentioned mobile phase and visualized under UV-light (254 or 366 nm) and ceric sulphate was sprayed on TLC plate to visualize spots of various constituents. The affinities of various constituents were measured in the form of retardation factor (Rf) values using the formula below.
Synthesis, characterization, radiolabeling and biodistribution of a novel cyclohexane dioxime derivative as a potential candidate for tumor imaging
Published in International Journal of Radiation Biology, 2018
M. A. Motaleb, Adli A. Selim, M. El-Tawoosy, M. H. Sanad, M. A. El-Hashash
The radiochemical yield was determined by PC using two mobile phases; acetone (Fisher scientific, Pittsburgh, PA, USA), (colloid and 99mTc complex at Rf (retardation factor) = 0.0, free 99mTcf = 0.9–1.0) and saline (Adwic, Cairo, Egypt), (colloid at Rf = 0.0, 99mTc complex and free 99mTcf = 0.9–1.0) as a mobile phase.
Related Knowledge Centers
- Chromatography
- Column Chromatography
- Paper Chromatography
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- Thin-Layer Chromatography