Application of high‐field NMR spectroscopy for characterization and quantitation of submilligram quantities of isolated natural products. (20th August 2015)

• Record Type: Journal Article
• Authors: Krunić, Aleksej; Orjala, Jimmy
• Is Part Of: Magnetic resonance in chemistry. Volume 53:Number 12(2015:Dec.)
• Page Start: 1043
• Page End: 1050
• Publication Date: 2015-08-20
• Subjects: NMR -- 1H -- 13C -- 15 N -- 900 MHz -- qNMR -- Shigemi microcell assembly -- internal standard -- cryoprobe; Nuclear magnetic resonance spectroscopy -- Periodicals; Chemistry, Organic -- Periodicals; Magnetic resonance -- Periodicals; 538.36
• DOI: 10.1002/mrc.4304
• Languages: English
• ISSNs: 0749-1581

Abstract

Abstract : We have investigated and compared a number of sample conditions on different NMR platforms in the search of maximum SNR and optimal experiment time efficiency for structure elucidation and quantitation of natural products. Using restricted volume 3 mm Shigemi microcell assembly in conjunction with a 900 MHz NMR spectrometer equipped with a 5 mm carbon‐sensitive inverse cryoprobe, it was possible to achieve a substantial increase in SNR (46‐fold) as compared with a conventional room temperature 400 MHz instrument. Switching from standard 5 mm NMR tube to 3 mm Shigemi microcell assembly typically improved SNR by threefold on either 600 or 900 MHz cryoplatform. A quantitation method that relies on a calibrated residual protonated NMR solvent signal as internal standard was developed using the same hardware setup and restricted sample volume tubes. Linearity of the method spans over 3 orders of magnitude, from low microgram to milligram quantities. We successfully applied this method to quantify a low micrgram sample of paclitaxel, verified by a UV/VIS quantitation measurement. Copyright © 2015 John Wiley & Sons, Ltd. Abstract : Comparisons of SNR achieved with a combination of different NMR sample tubes and across various NMR platforms. Maximum enhancements at ultrahigh field were applied to structure characterization and quantitation of natural products.