For example, 19 eq. of an unknown enantiomeric mixture of 10CSA was complexed with 22-P (Figure ). The inner core system shows clearly split resonance signals with ∆σ = 0.13 ppm. A small addition of 10CSA(R) decreased ∆σ (0.051 ppm), while a similar amount of 10CSA(S) increased ∆σ (0.224 ppm) revealing the predominant enantiomeric identity (S > R). Next, a linear calibration plot with 7 data points (e.e.10CSA(S) = 0, 48, 58, 69, 79, 90, 100 %) was constructed. It is worth noting that it is possible to generate a calibration curve from a single measured enantiopure point due to the linear dependency with the second point being ∆σ = 0 ppm. where e.e. = 0%. Lastly, the ∆σ can be fitted to the calibration plot and reveal the unknown e.e. (21%) based on the inner N-H chemical shift difference between the split peaks (for more information on this example see figure ). The same principle can be applied to quickly test the purity of enantiomers, i.e. by equally pre-mixing stereoisomers of interest with opposite chirality, in the event of matching purity, the 22-P signals will remain isochronous. Overall, monitoring changes of this inner core system in a model chiral environment demonstrates a powerful tool for easy and sensitive detection of enantiomeric compositions. ). On the right side: calculations of the unknown ee from the calibrated curve and using a one-point system. Note, calculations using a one-point system should only be used for quick, approximate determinations of the ee.