The Separation of Racemic Flavanone on Epitomize™ CSP-1 Chiral Stationary Phases

David W. House and Asha Oroskar, Orochem Technologies, Inc.

The optical isomers of flavanone have been separated using the Epitomize^™ CSP-1 series of chiral stationary phases. A separation value of 2.52 was obtained using CSP-1A with methanol as the mobile phase. A value of 1.70 was obtained using CSP-1K with a 95/5 blend of heptane/2-propanol as the mobile phase.

The Epitomize CSP-1 series of CSPs includes four derivatized polysaccharides that are coated onto modified silica gel. These CSPs, which are described in Table I, have been used to separate racemic flavanone using both normal and polar mobile phases.

Table I: The Epitomize™ CSP-1 Series of chiral stationary phases

Experimental

All columns were 4.6 mm I.D. by 250 mm long and the CSP particle size was 5 microns. The normal phase mobile phases were blends of 2-propanol (IPA) and n-heptane and the polar phases were methanol or acetonitrile. The flow rate was 1 mL/min in all cases. The column temperature was 25 °C and detection was at 254 nm.

Results

The best separation value observed using normal phase conditions was 1.70 and was obtained using CSP-1K with 95/5 heptane/IPA as the mobile phase. Table II summarizes the results for flavanone on all four CSPs with normal phase mobile phases.

Table II: Normal phase separation of flavanone on CSP-1A, 1C, 1K, and 1Z

Flavanone was rerun on CSP-1A and CSP-1C with methanol as the mobile phase at a flow rate of 1 mL/min. The results obtained for CSP-1A are particularly interesting. Although CSP-1A showed essentially no separation of racemic flavanone using 90/10 heptane/IPA as the mobile phase, when pure methanol was used the separation value was 2.52. This separation is shown in Figure 1. Using acetonitrile as the mobile phase led to a separation value of 1.98. The separation of racemic flavanone on CSP-1C with methanol as the mobile phase showed a decrease compared to heptane/IPA. These results are listed in Table III.

Figure 1: Separation of flavanone on CSP-1A, 5 µm, using methanol at 1 mL/min. Separation value of 2.52.

All of these separations can be scaled up to preparative and simulated moving bed (SMB) chromatography.

Table III: Polar phase separation of flavanone on CSP-1A and 1C

Conclusion

Excellent separation of the optical isomers of flavanone can be obtained using Epitomize CSP-1K with normal phase, mobile phases, and CSP-1A with polar mobile phases.

Orochem Technologies, Inc.

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