1 Reply Latest reply on Feb 22, 2019 12:36 AM by noreuter

    Normal phase to Reverse phase method development


      I work in a university analytical lab. I have a Thermo Dionex uHPLC that we run in reverse phase. I currently have a student who wants to determine the purity of some NMPA he has synthesised using a Zorbax C18 column; and then establish the raecemic ratios on a chiral column (Chirobiotic T). The paper he is working from gives him a normal phase method using a mobile phase of 50:50 hexane:IPA. I would rather not have to swap our system to normal phase for one project thus I would like to see if it is possible to change the method to use reverse phase solvents. I have little experience in HPLC method development, and none in converting between normal and reverse phase solvents. Can anybody help? What reverse phase solvents and ratios can I substitute for 50:50 hexane: IPA? Or any other starting suggestions would be appreciated. Thanks.

        • Re: Normal phase to Reverse phase method development

          NMPA is an acronym you know very well, but it is used for several different chemical components. Please post the real name(s) or even structure(s) so the community might be able to help.

          Anyway, there is no magical function to transform normal phase (NP) into reversed phase (RP) conditions. You typically use RP when the hydrophobicity (log P) of a molecule is greater than 1.5, i. e. it will have retention on C18 phases (or other). Below 1.5 NP is the technique to use as polar interactions rule. And then there is HILIC, a kind of aqueous normal phase technique. But all depends on the chemical structure of the analyte.

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