The invention relates to a configurational stereoisomer, referred to as enantiomer E4, of flocoumafen, said enantiomer E4 having, as determined by the chromatographic analysis of flocoumafen comprising four configurational stereoisomers of flocoumafen, carried out under conditions described hereinafter, a retention time t4 with a value such that t1 < t2 < t3 < t4; t1, t2 and t3 representing the retention times of the configurational stereoisomers of flocoumafen different from said enantiomer E4, said analysis being carried out at a temperature of 23.5°C.