Biomaterial Database

Solubility of long-chain fatty acids in phosphate buffer at pH 7.4. 1992

H Vorum, and R Brodersen, and U Kragh-Hansen, and A O Pedersen

Institute of Medical Biochemistry, University of Aarhus, Denmark.

The solubility of the saturated fatty acids lauric, myristic, palmitic, and stearic acid and the unsaturated oleic acid at 37 degrees C in phosphate buffer (pH 7.4) was estimated by using two independent methods. The one was a conventional solubility technique measuring the concentration of dissolved fatty acid in buffer by using radioactive compounds. The other was a dialysis exchange technique monitoring possible aggregation of solvated fatty acid anions by measuring the rate of diffusion of labelled compound across a dialysis membrane under conditions of chemical equilibrium. It was found that the results were strongly dependent on the radiochemical purity of the fatty acids. Using highly purified samples of radioactively labelled fatty acids, the solubility of monomeric laurate was shown to be greater than 500 microM, whereas the solubility of monomeric myristate was found to be 20-30 microM. Palmitate, stearate, and oleate solutions, on the other hand, showed a tendency to aggregation even at concentrations below 1 microM. Special attention was given to palmitate, as a reference compound for long-chain fatty acids, and the solubility of monomeric palmitate was estimated to be lower than 10(-10) M.

UI	MeSH Term	Description	Entries
D010169	Palmitic Acids	A group of 16-carbon fatty acids that contain no double bonds.	Acids, Palmitic
D010710	Phosphates	Inorganic salts of phosphoric acid.	Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
D002855	Chromatography, Thin Layer	Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Thin-Layer,Thin Layer Chromatography,Chromatographies, Thin Layer,Chromatographies, Thin-Layer,Thin Layer Chromatographies,Thin-Layer Chromatographies,Thin-Layer Chromatography
D003956	Dialysis	A process of selective diffusion through a membrane. It is usually used to separate low-molecular-weight solutes which diffuse through the membrane from the colloidal and high-molecular-weight solutes which do not. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Dialyses
D005227	Fatty Acids	Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)	Aliphatic Acid,Esterified Fatty Acid,Fatty Acid,Fatty Acids, Esterified,Fatty Acids, Saturated,Saturated Fatty Acid,Aliphatic Acids,Acid, Aliphatic,Acid, Esterified Fatty,Acid, Saturated Fatty,Esterified Fatty Acids,Fatty Acid, Esterified,Fatty Acid, Saturated,Saturated Fatty Acids
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D001345	Autoradiography	The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)	Radioautography
D012995	Solubility	The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Solubilities
D019308	Palmitic Acid	A common saturated fatty acid found in fats and waxes including olive oil, palm oil, and body lipids.	Hexadecanoic Acid,Calcium Palmitate,Sodium Palmitate,Acid, Hexadecanoic,Acid, Palmitic,Palmitate, Calcium,Palmitate, Sodium