Enantiomer fractions are preferred to enantiomer ratios for describing chiral signatures in environmental analysis

The enantiomer ratio (ER) is currently the standard descriptor of enantiome ric (chiral) signatures for environmental samples. In this paper, we argue for the adoption of the enantiomer fraction (EF) as the standard descriptor by showing drawbacks to the use of ER. The enantiomer fraction is superior because it provides a more meaningful representation of graphical data and is more easily employed in mathematical fate expressions. Several useful e xpressions are presented that allow EF to be used for tracking and apportio ning chemical movement between environmental compartments and for investiga ting microbial degradation processes.