Heat-bath cooling is a component of practicable algorithmic cooling of spins, an approach which might be useful for in vivo (13)C spectroscopy, in particular for prolonged metabolic processes where substrates that are hyperpolarized ex-vivo are not effective. We applied heat-bath cooling to 1,2-(13)C(2)-amino acids, using the a protons to shift entropy from selected carbons to the environment. For glutamate and glycine, both carbons were cooled by about 2.5-fold, and in other experiments the polarization of C1 nearly doubled while all other spins had equilibrium polarization, indicating reduction in total entropy. The effect of adding Magnevist (R), a gadolinium contrast agent, on heat-bath cooling of glutamate was investigated. (C) 2011 Elsevier B.V. All rights reserved.