21 CFR § 184.1165 - n-Butane and iso-butane.
(a) n-Butane and iso-butane (empirical formula C4H10, CAS Reg. Nos. 106-97-8 and 75-28-5, respectively) are colorless, flammable gases at normal temperatures and pressures. They are easily liquefied under pressure at room temperature and are stored and shipped in the liquid state. The butanes are obtained from natural gas by fractionation following absorption in oil, adsorption to surface-active agents, or refrigeration.
(b) The ingredients must be of a purity suitable for their intended use.
(c) In accordance with § 184.1(b)(1), these ingredients are used in food with no limitations other than current good manufacturing practice. The affirmation of these ingredients as generally recognized as safe (GRAS) as direct human food ingredients is based upon the following current good manufacturing practice conditions of use:
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