A sample of a chiral compound in which the minor enantiomer is detectable certainly is not enantiopure. However, what is an enantiopure compound?

The chemist's pragmatic answer is the following:

A sample in which the minor enantiomer is not detectable by the methods available is considered enantiopure.

Thus enantiopurity is a matter of progress in analytical methods: Today yes, tomorrow no.

This situation is dissatisfying. A given compound sample has a certain enantiomer composition, independent of whether we are able to exactly measure it. Let us ignore this problem for a moment, or let us equivalently assume to have an analytical method of any desired accuracy.

We are then faced with another even more fundamental problem: An enantiopure sample then is a sample not containing any amount of the minor enantiomer, or a sample of [R]/[S] = . Such a sample does not exist!