A case is made that either inductively coupled plasma-mass spectrometry or electrospray-mass spectrometry alone will not be adequate for the identification of unknown elemental species at trace levels in complex mixtures. These two types of ion source can be readily combined to provide both selective elemental analysis and molecular identification. The liquid flow rate regimes of these two measurement techniques are such that little compromise is expected if the two are used simultaneously on the same liquid chromatographic effluent. (C) 1998 Elsevier Science B.V.