The present invention relates to method for assessing the H2S release capacity of a liquid sample containing one or more sulfur compounds which are able to be degraded into gaseous H2S with temperature. The method comprising: a) Placing a volume of the liquid sample in a purge vessel so as to obtain a liquid phase and a gaseous phase in a flask; b) Purging the gaseous phase with an inert gas stream for a determined period of time; e) Passing the purged gaseous phase through a H2S trap; d) Recovering H2S from the H2S trap; and e) Dosing the recovered H2S. The invention is also used in a method for selecting a liquid sample, in particular among a group of different liquid samples.