The article reports on an attractive single-channel microchip manifold that offers convenient distinction between ‘total’ and ‘individual’ phenolic pollutants. Because of the toxicological significance of phenolic compounds, a reliable method is required for their environmental monitoring. Compact systems, suitable for field measurements of phenols, are preferred since they afford the option of rapid warning and avoid errors and delays inherent to laboratory-based analyses. Since most phenols are oxidizable at moderate potentials, electrochemistry can serve as a highly sensitive tool for their microchip detection [5]. In the present work, switching between ‘total’ and ‘individual’ phenol measurements is accomplished by rapidly changing the pH of the run buffer from an acidic one (where the phenols are neutral and not separated) to a basic one (that leads to the ionization and separation; Fig. 1). Repetitive flowinjection ‘total’ measurements are thus performed for providing a timely warning and alarm. Switching to the ‘separation’ mode takes place only when the ‘total’ flow-injection screening assay indicates the presence of phenolic compounds. Such microchip warning-alarm/identification capability meets the demands of many practical environmental-monitoring scenarios. An analogous microchip monitoring of ‘total’ and ‘individual’ explosive compounds based on switching between SDS-free and SDS containing buffers was described [6].