A simple expression for the local energy loss rate in binary mixtures is derived that can be used to analyze measured dielectric spectra, to check their validity or to control whether the specified material composition is consistent. Together with well-known permittivity bounds it is applied to analyze recently published data on microwave absorption of emulsions containing aqueous micro- and nano-droplets. It follows that these data are inconsistent and violate energy conservation. (c) 2007 Elsevier Inc. All rights reserved.