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Analysis of Regulated Drugs Using Chromatographic and Spectrophotometric Techniques Coupled with Spectroscopy An Orthogonal Approach to Protecting Public Health

Nickum, Elisa A
http://orcid.org/0000-0002-1856-4416
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504799568245931

Abstract Details

2017, PhD, University of Cincinnati, Arts and Sciences: Chemistry.
A considerable number of dietary supplements suspected of containing phosphodiesterase-5 (PDE-5) inhibitors and substituted phenethylamines have been analyzed by the U.S. Food and Drug Administration. Often these samples are found to contain the active pharmaceutical ingredients (API) such as sildenafil or phentermine, and in many cases, products contain multiple PDE-5 inhibitors or substituted phenethylamines. In an analytical setting, it is important to confirm the presence of any API with two or more independent methods, and this requirement can often put undo strain on a laboratory. The development and use of methods that inherently contain two unique identification techniques is preferred, and the creation and validation of three of those methods is outlined here. First, direct deposit Fourier transform infrared detection and mass spectrometric detection (GC/FT-IR/MS) is used to identify PDE-5 inhibitors. Generally, GC/MS is not generally used for this category of drugs due to low volatility; PDE-5 inhibitors often co-elute and can produce non-specific electron ionization fragmentation patterns. In contrast, FT-IR has been proven to be more selective for identifying PDE-5 inhibitors, but is generally not as sensitive as spectrometric techniques. However, it has been shown that each technique can compensate for the other, which allows a wider range of usability. Using this combined technique can save time and resources while still delivering a high level of certainty in identification by providing results from two scientifically uncorrelated techniques. Multiple reference standards were utilized for method validation, including determination of linearity, dynamic range, and limit of detection. Second, a single HPLC-UV method has been developed for the determination of PDE-5 inhibitors and related analogs in pharmaceutical dosage forms and dietary supplement products. Using this protocol, 14 PDE-5 inhibitor compounds can be separated and determined in a single analysis. Multiple reference standards were utilized for method validation, including determination of linearity, dynamic range, injection precision, limits of detection and quantitation, accuracy and precision. It was also demonstrated that, in cases where a standard for a specific analog is not readily available, another reference standard can be used to approximate the level of analog present, based on similarities in their chemical structures and absorbance spectra. Third, an HPLC-UV method has been developed for the determination of substituted phenethylamines in pre-workout dietary supplements. The number of these products on the market has greatly increased in recent years, and the labeled ingredients did not seem to account for amazing energy and euphoria experienced by users. Using GC-MS analysis, methamphetamine-like compounds are often detected but can be difficult to identify; as standards are not always available for comparison. To characterize any new analog, it is necessary to separate it from the matrix using an acid-base extraction, followed by HPLC-UV fraction collection and characterization using HRAM-MS and nuclear magnetic resonance. Recently, these techniques were used to characterize N-ethyl-a-ethylphenethylamine in a powdered drink supplement. Using this HPLC-UV method, five substituted phenethylamines can be separated and determined in a single analysis. Multiple reference standards were utilized for method validation, including determination of linearity, dynamic range and injection precision.
Peng Zhang, Ph.D. (Committee Chair)
Anna Gudmundsdottir, Ph.D. (Committee Member)
Laura Sagle, Ph.D. (Committee Member)
86 p.
Chemistry
PDE 5 Inhibitor; GC MS; FT IR; HPLC UV; GC FT IR MS; Phenethylamine

Recommended Citations

Citations

  • Nickum, E. A. (2017). Analysis of Regulated Drugs Using Chromatographic and Spectrophotometric Techniques Coupled with Spectroscopy An Orthogonal Approach to Protecting Public Health [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504799568245931

    APA Style (7th edition)

  • Nickum, Elisa. Analysis of Regulated Drugs Using Chromatographic and Spectrophotometric Techniques Coupled with Spectroscopy An Orthogonal Approach to Protecting Public Health. 2017. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504799568245931.

    MLA Style (8th edition)

  • Nickum, Elisa. "Analysis of Regulated Drugs Using Chromatographic and Spectrophotometric Techniques Coupled with Spectroscopy An Orthogonal Approach to Protecting Public Health." Doctoral dissertation, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504799568245931

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.