Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  :10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity. 
The chemistry, biochemistry, and physiological activity of steroids are under intense study in light of the great importance of steroids in medicine, veterinary science, and animal husbandry. In industry, chemical and microbiological methods have been introduced for the partial synthesis of steroid hormones from available raw materials (sterols, bile acids, saponins), and in the 1960’s and 1970’s methods have been introduced for complete chemical synthesis from the simplest starting materials. The synthesis of “artificial” steroid hormones with specialized physiological effects (contraceptive, anabolic), in particular, fluorine-containing and nitrogen-containing analogs, is acquiring increasing importance.