Enantiomeric excess

Enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a single completely pure enantiomer has an ee of 100%. A sample with 70% of one enantiomer and 30% of the other has an ee of 40% (70% − 30%).   % e e = ( | F R − F S | × 100 )   {displaystyle \%ee=({|}F_{R}-F_{S}{|} imes 100) }     (1)   % e e = ( ( R − S ) / ( R + S ) × 100 )   {displaystyle \%ee=((R-S)/(R+S) imes 100) }     (2) Enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a single completely pure enantiomer has an ee of 100%. A sample with 70% of one enantiomer and 30% of the other has an ee of 40% (70% − 30%). Enantiomeric excess is defined as the absolute difference between the mole fraction of each enantiomer: