The invention relates to a sampling valve, for taking samples of fluid from a common collecting vessel in order to perform a plurality of analyses using reagents. The valve of the invention comprises two members that are movable relative to each other, comprising a sampling member having sampling loops, each intended to receiving an aliquot of fluid, and a connection member capable of assuming at least three functional positions relative to the sampling member. These three positions enable the delayed access to two separate sampling circuits in order to fill them and to dispense reagents to the loops that make them up.