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.

Silicon compounds are the most abundant component of the Earth's crust. Sand is the primary source of silicon due to its abundance, simplicity of mining, and processing. Quartzite, a metamorphic rock, is another potential source. Silicon (Si) is classified as semi-metallic or metalloid since it has certain metallic qualities. Silica gel was first discovered in the 1640s as a scientific curiosity. During World War I, it was used to absorb vapors and gases from gas mask canisters. Walter A.

The Relative Response Factor (RRF) is an analytical measure used in chromatographic processes to monitor impurities/degradants in drug substances and drug products. RRF is utilized to compensate for the disparity in detector response of contaminants vs. analyte peak. It is established using the slope approach with a linear range of solutions. 

Process-related impurities are undesirable substances found in biopharmaceutical samples. These chemicals can be cell substrates, come from the production process (e.g., nutritional medium, initiators of protein production and selection, chemicals utilized in further purification), or be the result of chemical alterations to the product.

Nuclear magnetic resonance spectroscopy (NMR) is a common and successful technique that uses the magnetic properties of individual nuclei. When exposed to an external magnetic field, some nuclei exhibit distinct nuclear spin states, which is the underlying premise of NMR. NMR identifies transitions between spin states specific to the nuclei in issue, as well as their chemical surroundings. However, this only applies to nuclei with spins other than zero; nuclei with spins equal to zero are 'invisible' to NMR spectroscopy.