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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. 
Unfortunately there exists no test that can determine a bodybuilder's detailed drug use in the far past, and doping test results are very easy to manipulate . Therefore, if you really want to know whether a bodybuilder is true natural, or which drugs he has been using to build his physique, you will have to ask him. The standard answer to this question is, however, always "No, I have never used any drugs". However, if you get to know the guy better, develop some friendship, give him some complements on his physique, and especially if he thinks that you are a drug user yourself or interested in becoming one, he might well loosen up and start telling you at least part of his true story.