A molecule is a combination of two or more atoms bound together by attractive forces known as chemical bonds; depending on the context, the phrase may or may not include ions that meet this requirement. In quantum physics, organic chemistry, and biochemistry, the difference between molecules and ions is typically ignored, and the term molecule is commonly used to refer to polyatomic ions. Atoms are the essential constituents of an element. They are made up of a nucleus and surrounding electrons. Valence electrons occur when an atom's electron shell is inadequate.
A polymer is any of a family of natural or synthetic compounds made up of larger molecules known as macromolecules, which are multiples of smaller chemical units called monomers. Many components found in living creatures are polymers, such as proteins, cellulose, and nucleic acids. Furthermore, they are the building blocks for minerals like diamond, quartz, and feldspar, as well as man-made materials like concrete, glass, paper, plastics, and rubbers. The word polymer refers to an unspecified number of monomer units.
An analytical instrument called a UV-vis spectrophotometer measures how much ultraviolet (UV) and visible light a sample absorbs. In chemistry, biochemistry, and other sciences, it is a widely used method for locating and measuring compounds in a variety of materials.
Preparative chromatography is the process of isolating material from a sample using HPLC, usually in large amounts, by collecting separated peak fractions as they emerge from the detector. The basic objective of an analytical-scale separation is to provide a chromatogram with crisp, well-resolved, symmetrical peaks that provide the necessary analytical information.
Reversed-phase chromatography (RPC) is a liquid chromatography technology that separates molecules using hydrophobic interactions between solute molecules in the mobile phase and ligands linked to the stationary phase.
The World Health Organization (WHO) is a United Nations body focused on global health and safety. The Organization brings together states, partners, and individuals to promote health, keep the world secure, and help the vulnerable. As a result, anyone, anywhere can achieve optimal health.
An official publication, first published by the American Pharmaceutical Association and now yearly by the United States Pharmacopeial Convention, that contains the composition, description, method of manufacture, and dose of medications. The book includes two independent official compendia: the USP and the NF.
Thin layer chromatography (TLC) is a chromatographic technique for separating mixture components that uses a thin stationary phase supported by an inert backing. It can be done on an analytical scale to track the development of a reaction, or on a preparative scale to purify small amounts of a product. TLC is a popular analytical tool because of its simplicity, low cost, great sensitivity, and rapidity of separation. TLC works on the same concept as all chromatography: a molecule has varying affinities for the mobile and stationary phases, which affects the rate at which it migrates.