title: Online NMR and HPLC as a reaction monitoring platform for pharmaceutical process development.
abstract: Detector response is not always equivalent between detectors or instrument types. Factors that impact detector response include molecular structure and detection wavelength. In liquid chromatography (LC), ultraviolet (UV) is often the primary detector; however, without determination of UV response factors for each analyte, chromatographic results are reported on an area percent rather than a weight percent. In extreme cases, response factors can differ by several orders of magnitude for structurally dissimilar compounds, making the uncalibrated data useless for quantitative applications. While impurity reference standards are normally used to calculate UV relative response factors (RRFs), reference standards of reaction mixture components are typically not available during route scouting or in the early stages of process development. Here, we describe an approach to establish RRFs from a single experiment using both online nuclear magnetic resonance (NMR) and LC. NMR is used as a mass detector from which a UV response factor can be determined to correct the high performance liquid chromatography (HPLC) data. Online reaction monitoring using simultaneous NMR and HPLC provides a platform to expedite the development and understanding of pharmaceutical reaction processes. Ultimately, the knowledge provided by a structurally information rich technique such as NMR can be correlated with more prevalent and mobile instrumentation [e.g., LC, mid-infrared spectrometers (MIR)] for additional routine process understanding and optimization.
authors.affiliation: Analytical Research and Development, Pfizer Worldwide Research and Development , Eastern Point Road, Groton, Connecticut 06340, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Foley
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Brent
authors.initials: B
authors.lastname: Maranzano
authors.forename: Mark T
authors.initials: MT
authors.lastname: Zell
authors.forename: Brian L
authors.initials: BL
authors.lastname: Marquez
authors.forename: Yanqiao
authors.initials: Y
authors.lastname: Xiang
authors.forename: George L
authors.initials: GL
authors.lastname: Reid
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D015394:Molecular Structure; D009862:Online Systems / Q000295:instrumentation*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D013678:Technology, Pharmaceutical / Q000295:instrumentation*
chemical_list: D004364:Pharmaceutical Preparations