The ‘Two-Pin’ technique increases sanitation for multiple dose vial users. They draw with the first pin, and then shoot/inject into the body with a new one. This procedure prevents any residual contaminants that may have remained on the drawing pin from being transferred into the body via the injection site. It also makes injection less painful since the drawing needle is necessarily dulled during passage through the rubber stopper atop the vial. A dulled needle increases injection pain because it doesn’t pierce the body as cleanly as an unused one. The protocol below is followed by AAS users who draw from multiple dose vials, but steps 4 - 8 are routinely disregarded by those users who draw from ampoules (also called ampules) and sachets.
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. 
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