A method of transferring mass of at least one solute between a liquid first phase and a fluid second phase that is immiscible with the first phase, the method comprising moving at least one droplet of said liquid first phase in a microfluidic device by using electric-type forces (electrowetting or dielectrophoresis) within a space that is filled with said fluid second phase. Said droplet is preferably moved by said electric-type forces along a path between a point for injecting said droplet into said microfluidic device, and an extraction and/or analysis zone, said path being defined in such a manner that said droplet sweeps through a significant fraction of said space filled with said fluid second phase. The method may include a step of transferring said droplet using said electric-type forces to a chemical analysis device integrated in said microfluidic device, and a step of chemically analyzing said droplet. The invention also provides a device for implementing such a method.