Isomer Separation? Welch columns bring help

July 3, 2019

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Isomer

In Chemical world, there also exist some compounds with similar structure and properties like isomer and enantiomer. It’s very hard to operate chromatography separation on these compounds, for example, Oleanolic acid and Ursolic acid.

To separate these compounds, we need to identity their own characters and choose the right column with unique selectivity. Enantiomer usually can get separation on chiral columns, but today, we will talk about the separation of isomers.

Welch columns with steric hindrance to separate isomers:

Ultisil XS-C18、Ultisil PFP、Ultisil PAH and Ultisil XB-C30

Separation of Oleanolic acid and Ursolic acid on Ultisil XS-C18 and Ultisil XB-C30

Chromatography condition:

Mobile Phase: Acetonitrile: water=93:7

Detector: 210nm

Temperature: 20℃

Flow Rate: 1ml/min

Injection Volume: 10μl

Chromatogram of reference solution on Ultisil XS-C18

Chromatogram of reference solution on Ultisil XB-C30

Conclusion: Ultisil XS-C18 and Ultisil XB-C30 can satisfy the test requirements on separation of Oleanolic acid and Ursolic acid.

Separation of α, β, γ, δ tocopherol on Ultisil PFP

Tocopherol is a hydrolysate of vitamin E. Natural tocopherol is d-tocopherol and it has many isomers like α, β, γ, δ.

Chromatography condition:

Mobile Phase: Methanol/water(Gradient Elution)

Detector: 294nm/325nm

Temperature: 20℃

Flow Rate: 0.8ml/min

Injection Volume: 10μl

Mixed Reference Chromatogram

Conclusion: The fluorine-containing stationary phase of Ultisil PFP has strong geometry and stereo shape selectivity, which can easily help to separate compound with similar structure. It perfectly meets the requirement in this experiment.

Separation of main component and isomer impurities on Ultisil PAH