A growing focus in the field of green analytical chemistry has been the development of greener solvents. Thus, the idea of replacing toxic solvents used in high performance liquid chromatography (HPLC) has become a priority. Previous work has shown that dimethyl carbonate (DMC) is a useful replacement for acetonitrile in hydrophilic interaction liquid chromatography (HILIC). The utility of DMC as a modifier solvent in normal phase chromatography (NPLC) and reverse phase chromatography (RPLC) was investigated. First, to explore the value of DMC as a modifier solvent in NPLC, the separation of phthalates was investigated. Phthalates are plasticizers commonly used in soft plastics that pose various health risks, and thus, a method of separation for these compounds is of interest. Typical separations of phthalates utilize n-hexane and ethyl acetate as the eluent. DMC was investigated as an alternative modifier solvent to ethyl acetate. Dioctyl, dibutyl, benzyl butyl, diethyl and dimethyl phthalate were analyzed in varying composition of hexanes and ethyl acetate or DMC. The retention factor k and plate count were comparable between the two solvents with stronger retention using DMC. The lower UV cutoff of DMC provides an advantage over ethyl acetate, exemplifying its utility in NPLC. An application of RPLC is the determination of the solvent strength parameter, S. There is a lack of information in literature about the strength of DMC as a solvent. Therefore, determination of S is necessary to understand its utility in HPLC separations. Caffeine, sulfathiazole, and para- and 2-nitroaniline, were analyzed in 1% to 10% organic modifier for acetonitrile (MeCN), DMC, and ethanol (EtOH). Retention of these solutes were similar between MeCN and EtOH as the organic modifiers and much less with DMC showing that DMC is a stronger solvent compared to MeCN, a property that can be advantageous in certain RPLC applications.
Author: Sophie Elleman, Chemistry and Neuroscience
Advisor: Neil Danielson, Chemistry and Biochemistry
Graduate Advisor: Philip Boes, Chemistry and Biochemistry
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