Abstract: A flow-through electrochemical cell distinguished by the feature of a working electrode comprising selected carbon black powder(s) dispersed within an inert binder. An outstanding characteristic of the invention is the markedly improved signal/noise ratio of the electrode which enables a significant gain in the sensitivity level at which trace compounds can be detected. As an example of utility, as little as 5 to 30 parts per billion (ppb) of most phenolic compounds in water can be determined by liquid chromatographic separation of species and amperometric electrochemical detection, using the described flow-through cell to monitor the column effluent. No sample preparation is required.