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Hydrophilic interaction and micellar liquid chromatography approaches for the separation of aromatic carboxylic acid positional isomers plus ion exchange chromatography for the separation of sulfonated compounds

Richardson, Ashley E

Abstract Details

2017, Doctor of Philosophy, Miami University, Chemistry and Biochemistry.
Separation of aromatic positional isomers is typically limited to separating a couple of the isomers in a class, not all of them. A novel HILIC method has been developed to separate ten aromatic carboxylic positional isomers, including the hydroxybenzoic acid isomers, hydroxycinnamic acid isomers, syringic, vanillic, ferulic, and sinapic acids, using a ternary mobile phase comprised of acetonitrile, ammonium acetate buffer, and pentane. This method is compatible with mass spectrometry (MS) detection and can separate the analytes in under 45 minutes with baseline resolution of all isomers. Terephthalic acid purity is extremely important during the production of polyethylene terephthalate. There are few methods available that can separate terephthalic acid from eight major impurities. Those impurities include two sets of positional isomers. Using micellar liquid chromatography (MLC), a method has been developed using an acidic sodium dodecyl sulfate (SDS) mobile phase, a C18 column, and a flow rate gradient to separate terephthalic acid from the eight impurities in less than 20 minutes with baseline resolution. Detection limits have been improved when compared to previous methods. This method is also inexpensive and environmentally friendly. Using the same set of analytes, the use of SDS and Brij-35 surfactants in MLC under ultra-high performance liquid chromatography (UHPLC) conditions is compared. While the UHPLC method using SDS is a slight improvement over the standard MLC method previously developed, the use of Brij-35 shows slightly longer analysis time. However, the use of Brij-35 could possibly allow for the use of MS detection as it is not entirely necessary to have Brij-35 in the mobile phase. Due to the adulteration of heparin in 2007 and 2008, quality control testing of heparin has become extremely important. Heparin and other glycosaminoglycans tend to have extremely broad peaks, excessive retention, and poor resolution. Therefore, model compounds will be used to optimize the separation conditions before applying the method to heparin and impurities. This method uses a cation exchange column that is modified with protamine to make an anion exchange column. By keeping protamine in the mobile phase, the column is constantly equilibrated. An acidic mobile phase consisting of protamine and sodium perchlorate has successfully separated naphthalene mono-, di-, and tri-sulfonate. Additionally, it has been able to positively identify a polystyrene sulfonate compound in a wrinkle serum.
Neil Danielson (Advisor)
Carole Dabney-Smith (Committee Chair)
Richard Taylor (Committee Member)
Jiangjiang Zhu (Committee Member)
Justin Saul (Committee Member)

Recommended Citations

Citations

  • Richardson, A. E. (2017). Hydrophilic interaction and micellar liquid chromatography approaches for the separation of aromatic carboxylic acid positional isomers plus ion exchange chromatography for the separation of sulfonated compounds [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1511295591427557

    APA Style (7th edition)

  • Richardson, Ashley. Hydrophilic interaction and micellar liquid chromatography approaches for the separation of aromatic carboxylic acid positional isomers plus ion exchange chromatography for the separation of sulfonated compounds. 2017. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1511295591427557.

    MLA Style (8th edition)

  • Richardson, Ashley. "Hydrophilic interaction and micellar liquid chromatography approaches for the separation of aromatic carboxylic acid positional isomers plus ion exchange chromatography for the separation of sulfonated compounds." Doctoral dissertation, Miami University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1511295591427557

    Chicago Manual of Style (17th edition)