one or more reservoirs storing the matrix gas or gases;

one or more high-pressure bottles storing the said constituent or constituents;

one or more high-pressure bottles storing one or more reference gases, configured to calibrate an analytical system;

a mixing chamber;

gas lines configured for conveying the mixing gases and the matrix gases to the mixing chamber, which gas lines are each equipped with one or more mass flow controllers;

a compression stage comprising a gas compressor;

a gas line configured for conveying the gas mixture formed in the mixing chamber to the compression stage, which compression stage is configured for pressurizing the gas mixture in order to fill each of the bottles of the said batch of bottles therewith;

an analytical system having selected analysers;

a gas line configured for conveying a part of the gas mixture formed in the mixing chamber to the analytical system configured to carry out real-time analysis of the gas mixture sampled in this way, which line is advantageously placed in bypass on the said gas line connecting the mixing chamber to the compression stage;

one or more filling stations making it possible to position the bottles of the said batch of bottles to be filled and suitable for distributing the gas mixture into each of the bottles of the said batch of bottles;

a gas line suitable for conveying the pressurized gas mixture from the compression stage to the filling station or stations, the filling station or stations being capable of being entirely full or partially populated with the bottles of the said batch of bottles;

one or more gas lines suitable for conveying a part of the pressurized gas mixture in the bottles of the said batch of bottles to the analytical system in order to be able in particular to perform a post-filling verification analysis of the bottles after the filling cycle;

conveying the gas mixture at the exit of the mixing chamber to the compression stage, which carries out an increase of the pressure of the mixture to a desired setpoint;

conveying the gas mixture at the exit of the compression stage to the filling station or stations and the distribution of the gas mixture into the said batch of bottles is carried out, and the filling is stopped once a pressure setpoint has been reached in at least one of the bottles of the said batch;

analysing on-line in real-time all the mixing components of the gas mixture by the analytical system at the exit of the mixing chamber and before entering the compression stage;

estimating in real-time the composition of the gas mixture in one of the bottles is carried out by real-time integration from the start of filling of the composition of the gas mixture leaving the mixing chamber or real-time composition of the gas mixture entering the bottle or bottles of the said batch of bottles as a function of the result of the said real-time analysis of the composition of the gas mixture coming from the mixing chamber, at a given instant; and

comparing this estimation with one or more setpoint values for the final concentration or concentrations intended in each of the bottles of the batch is carried out, and if necessary feedbacks are carried out automatically and in real time in order to modify the gas flow rates of each component of the mixture reaching the chamber, by modifying the setting of the mass flow controllers associated with each component, so as to maintain and/or correct upwards and/or correct downwards the particular concentrations of the components of the mixture leaving the mixing chamber, and thus to be able to continue the filling with a nominal composition or a composition enriched or depleted with respect to one or some of the components of the mixture.