title: Semi-preparative LC-SPE-cryoflow NMR for impurity identifications: use of mother liquor as a better source of impurities.
abstract: Unambiguous structural elucidation of active pharmaceutical ingredients (API) impurities is a particularly challenging necessity of pharmaceutical development, particularly if the impurities are low level (0.1% level). In many cases, this requires acquiring high-quality NMR data on a pure sample of each impurity. High-quality, high signal-to-noise (S/N) one- and two-dimensional NMR data can be obtained using liquid chromatography-solid phase extraction-cryoflow NMR (LC-SPE-cryoflow NMR) with a combination of semi-preparative column for separation and mother liquor as a source of concentrated impurities. These NMR data, in conjunction with mass spectrometry data, allowed for quick and unambiguous structural elucidations of four impurities found at low level in the crystallized API but found at appreciable levels in the mother liquor that was used as the source for these impurities. These data show that semi-preparative columns can be used at lower than ideal flow rates to facilitate trapping of HPLC components for LC-SPE-cryoflow NMR analysis without compromising chromatographic resolution. Also, despite the complex chromatography encountered with the use of mother liquor as a source of impurities, acceptably pure analytes were obtained for acquiring NMR data for unambiguous structure elucidations.
authors.affiliation: Analytical and Bioanalytical Development, Bristol-Myers Squibb, New Brunswick, NJ, USA. frank.rinaldi@bms.com
authors.forename: Frank
authors.initials: F
authors.lastname: Rinaldi
authors.forename: Junying
authors.initials: J
authors.lastname: Fan
authors.forename: Charles
authors.initials: C
authors.lastname: Pathirana
authors.forename: Venkatapurim
authors.initials: V
authors.lastname: Palaniswamy
mesh_terms: D002853:Chromatography, Liquid; D004340:Drug Contamination; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D015394:Molecular Structure; D012015:Reference Standards; D052616:Solid Phase Extraction
keywords: 13C; 1H; LC-SPE-NMR; NMR; cryoflow probe; impurity identification; mother liquor; semi-preparative chromatography