Disclosed is a configurational stereoisomer, referred to as enantiomer E.sub.4, of bromadiolone, having, as determined by the chromatographic analysis carried out under conditions described hereinafter, a retention time t.sub.4 with a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.1, t.sub.2 and t.sub.3 representing the retention times of each configurational stereoisomer of bromadiolone different from the enantiomer E.sub.4, the analysis being carried out at a temperature of 27.3 C.

Disclosed is a configurational stereoisomer, referred to as enantiomer E.sub.4, of bromadiolone, having, as determined by the chromatographic analysis carried out under conditions described hereinafter, a retention time t.sub.4 with a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.1, t.sub.2 and t.sub.3 representing the retention times of each configurational stereoisomer of bromadiolone different from the enantiomer E.sub.4, the analysis being carried out at a temperature of 27.3 C.

Disclosed is a configurational stereoisomer, named enantiomer E.sub.3, of bromadiolone having, by chromatographic analysis of a bromadiolone composition including four configurational stereoisomers of bromadiolone performed under the conditions described hereinbelow, a retention time t.sub.3 having a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.1, t.sub.2 and t.sub.4 being the retention times of the configurational stereoisomers of bromadiolone different from the enantiomer E.sub.3, the analysis being performed at a temperature of 27.3 C.

Disclosed is a configurational stereoisomer, named enantiomer E.sub.3, of bromadiolone having, by chromatographic analysis of a bromadiolone composition including four configurational stereoisomers of bromadiolone performed under the conditions described hereinbelow, a retention time t.sub.3 having a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.1, t.sub.2 and t.sub.4 being the retention times of the configurational stereoisomers of bromadiolone different from the enantiomer E.sub.3, the analysis being performed at a temperature of 27.3 C.

Disclosed is a configurational stereoisomer, referred to as enantiomer E.sub.2, of flocoumafen, the enantiomer E.sub.2 having, as determined by the chromatographic analysis of a flocoumafen composition including four configurational stereoisomers of flocoumafen, carried out under conditions described hereinafter, a retention time t.sub.2 with a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.1, t.sub.3 and t.sub.4 representing the retention times of the configurational stereoisomers of flocoumafen different from the enantiomer E.sub.2, the chromatographic analysis being carried out at a temperature of 23.5 C.

Disclosed is a configurational stereoisomer, referred to as enantiomer E.sub.2, of flocoumafen, the enantiomer E.sub.2 having, as determined by the chromatographic analysis of a flocoumafen composition including four configurational stereoisomers of flocoumafen, carried out under conditions described hereinafter, a retention time t.sub.2 with a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.1, t.sub.3 and t.sub.4 representing the retention times of the configurational stereoisomers of flocoumafen different from the enantiomer E.sub.2, the chromatographic analysis being carried out at a temperature of 23.5 C.

Disclosed is a configurational stereoisomer, named enantiomer E.sub.1, of bromadiolone having, by chromatographic analysis of bromadiolone including four configurational stereoisomers of bromadiolone performed under the conditions described below, a retention time t.sub.1 having a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.2, t.sub.3 and t.sub.4 being the retention times of the configurational stereoisomers of bromadiolone different from the enantiomer E.sub.1, the analysis being performed at a temperature of 27.3 C.

Disclosed is a configurational stereoisomer, named enantiomer E.sub.1, of bromadiolone having, by chromatographic analysis of bromadiolone including four configurational stereoisomers of bromadiolone performed under the conditions described below, a retention time t.sub.1 having a value such that t.sub.1<t.sub.2<t.sub.3<t.sub.4; t.sub.2, t.sub.3 and t.sub.4 being the retention times of the configurational stereoisomers of bromadiolone different from the enantiomer E.sub.1, the analysis being performed at a temperature of 27.3 C.

Disclosed is to a composition including difethialone, containing a configurational stereoisomer of difethialone, referred to as a hetero-stereoisomer, of formula 3-(4-bromobiphenyl-4-yl)-1-(4-hydroxythiocoumarin-3-yl)-1,2,3,4-tetrahydronaphthalene, in which the carbon atoms 1 and 3 of the 1,2,3,4-tetrahydronaphthalene group have different absolute configurations, the composition including an amount of a dextrorotatory enantiomer of the hetero-stereoisomer such that the ratio of this amount to the amount of difethialone in the composition is less than 10%; the amount of the dextrorotatory enantiomer of the hetero-stereoisomer of difethialone in the composition being different from the amount of levorotatory enantiomer of the hetero-stereoisomer of difethialone in the composition.

Disclosed is to a composition including difethialone, containing a configurational stereoisomer of difethialone, referred to as a hetero-stereoisomer, of formula 3-(4-bromobiphenyl-4-yl)-1-(4-hydroxythiocoumarin-3-yl)-1,2,3,4-tetrahydronaphthalene, in which the carbon atoms 1 and 3 of the 1,2,3,4-tetrahydronaphthalene group have different absolute configurations, the composition including an amount of a dextrorotatory enantiomer of the hetero-stereoisomer such that the ratio of this amount to the amount of difethialone in the composition is less than 10%; the amount of the dextrorotatory enantiomer of the hetero-stereoisomer of difethialone in the composition being different from the amount of levorotatory enantiomer of the hetero-stereoisomer of difethialone in the composition.