The present invention generally relates to methods for purifying and/or concentrating compounds from or in solutions and/or mixtures. In one embodiment, the present invention relates to a method for purifying and/or concentrating a compound from a solution or mixture. In another embodiment, the present invention relates to a method for purifying/concentrating a compound from a solution or mixture that utilizes, in whole or part, foam purification and/or concentration. In still another embodiment, the present invention can be used to separate, concentrate and/or purify any material, including biological products and/or biomaterials, that can be selectively bound to a binding agent, thereby yielding a complex that will readily partition onto bubble surfaces in a foam.