A method and to an equipment carry out measurements on an effluent resulting from a chemical reaction taking place in a reactor containing a catalyst. The method includes, in combination, injecting at least one feedstock into each of at least two reactors, separating the gas and liquid phases downstream from each reactor, sending the separated gas phase to be measured and analyzed while the other gas phases coming from the other separators are discharged, sending the separated liquid phase to be analyzed and measured, and automatically monitoring and controlling the chemical reaction in the reactors, the analysis and measurement cycle performed on the gas phase and the analysis and measurement cycle performed on the liquid phase.