Method for determining an extraction efficiency of at least one volatile species contained in a drilling mud, the method including: housing a test mud in a first closed container; determining a test parameter representative of a ratio between a first portion of at least one first volatile species, which is absorbed by the test mud, and a second portion of the first volatile species, which is not absorbed by the test mud, the second portion of the first volatile species being measured in a headspace of the first closed container; housing a drilling mud in a second closed container, the drilling mud containing at least one second volatile species, the second volatile species being substantially the same as the first volatile species; determining an operating parameter representative of a quantity of the second volatile species released by the drilling mud in the second closed container, wherein the quantity of the second volatile species is measured in a headspace of the second closed container; determining, as a function of the operating parameter and the test parameter, an absorption parameter indicative of a quantity of the second volatile species in the drilling mud; determining, as a function of the absorption parameter, an extraction efficiency of the second volatile species from the drilling mud.