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. 
For the off-season athlete there is no anabolic steroid more important or beneficial than testosterone. High levels of testosterone will promote significant increases in lean muscle mass and strength. This is assuming that the individual is consuming adequate calories. Compounds like Testosterone Propionate are not magical, you will still need to feed your body enough calories. During an off-season period of growth, this means total caloric intake will need to be slightly above maintenance. This will, unfortunately, promote body fat gain. However, the key to a successful off-season is gaining lean tissue while minimizing body fat gain to the fullest extent possible. By supplementing with Testosterone Propionate you will be able to achieve this more efficiently. High testosterone levels will promote a stronger metabolic rate. This is not a license to eat like there’s no end in sight, but you should be able to make better use of your calories.
While tremendously beneficial to the cutting phase and often considered essential to competitive bodybuilders during contest prep, Trenbolone Acetate is also a phenomenal off-season bulking steroid . When we refer to this hormonal compound as versatile, that is truly an accurate statement. There are very few anabolic steroids that can promote mass like Trenbolone Acetate. More importantly, the effects of Trenbolone Acetate in this regard are not only strong but are far cleaner than most traditional bulking steroids. This hormone will not and cannot promote water retention, meaning each and every pound of weight gained due to use will be lean muscle mass. Of equal importance will be this steroid’s ability to help the individual control fat gain during a period of growth. To achieve true growth, this will require total caloric intake to be slightly above maintenance levels. How far above will vary from one man to the next, and while many often take it too far, this phase will still require a slight surplus. Unfortunately, this necessary surplus will promote body fat gains but due to the metabolic factors that surround Trenbolone Acetate they will be minimized. This is not a license to eat like there’s no end in sight, you can still gain a lot of fat if you continually gorge but you should be able to make better use of your total caloric intake. Those who supplement with Trenbolone Acetate during off-season periods of growth should gain less body fat than they would have without it.