Simultaneous molecular formula determinations of natural compounds in a plant extract using 15 T Fourier transform ion cyclotron resonance mass spectrometry

Abstract

BackgroundPlant extracts are a reservoir of pharmacologically active substances; however, conventional analytical methods can analyze only a small portion of an extract. Here, we report a high-throughput analytical method capable of determining most phytochemicals in a plant extract and of providing their molecular formulae from a single experiment using ultra-high-resolution electrospray ionization mass spectrometry (UHR ESI MS). UHR mass profiling was used to analyze natural compounds in a 70% ethanol ginseng extract, which was directly infused into a 15 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer for less than 10 min without a separation process.ResultsThe UHR FT-ICR MS yielded a mass accuracy of 0.5 ppm and a mass resolving power (m/Δm) of 1,000,000–270,000 for the range m/z 290–1,100. The mass resolution was sufficient to resolve the isotopic fine structure (IFS) of many compounds in the extract. After noise removal from 1,552 peaks, 405 compounds were detected. The molecular formulae of 123 compounds, including 33 ginsenosides, were determined using the observed IFS, exact monoisotopic mass, and exact mass difference. Liquid chromatography (LC)/FT-ICR MS of the extract was performed to compare the high-throughput performance of UHR ESI FT-ICR MS. The LC/FT-ICR MS detected only 129 compounds, including 19 ginsenosides. The result showed that UHR ESI FT-ICR MS identified three times more compounds than LC/FT-ICR MS and in a relatively shorter time. The molecular formula determination by UHR FT-ICR MS was validated by LC and tandem MS analyses of three known ginsenosides.ConclusionsUHR mass profiling of a plant extract by 15 T FT-ICR MS showed that multiple compounds were simultaneously detected and their molecular formulae were decisively determined by a single experiment with ultra-high mass resolution and mass accuracy. Simultaneous molecular determination of multiple natural products by UHR ESI FT-ICR MS would be a powerful method to profile a wide range of natural compounds.

Chemical Diversity and Complexity of Scotch Whisky as Revealed by High-Resolution Mass Spectrometry

“…IFS has previously been used to confirm assignments [8, 58, 59], including the use of selectively isolating ions of interest [60]. An example of this is shown in Figure 2 using the assigned formula at 335.08058 m/z of C 13 H 19 O 8 S identified in the S14-2373 sample.…”

“…Natural organic matter (NOM) is a subject of intense research in developing methodology for its characterization at the molecular level [2–5]. Related to these efforts are studies of metabolites [6, 7], plant extracts [8], or indeed other foods or beverages [9–12]. This work thus contributes to achieving broader goals of analytical chemistry in the area of analysis of complex mixtures.…”

A simplified strategy for molecular formula determination of chemical constituents in traditional Chinese medicines based on accurate mass, A + 1 and A + 2 isotopic peaks using Fourier transform ion cyclotron resonance mass spectrometry

“…In recent years, the A + 1 and A + 2 isotopic peaks of ions detected using FTICR MS have been used to filter molecular formula candidates in many fields such as metabonomics, natural compounds and petroleomics 9–11,21,22 . Theoretically, a mass resolving power of 500 000 is required to perfectly generate the A + 1 and A + 2 isotopic peaks of chemical compounds with molecular weights of less than 1000 Da, because isotopic peaks derived from 15 N, 34 S and 18 O can be clearly resolved from the isotopic peaks of 13 C or 13 C 2 at this resolution 11 .…”

Mass spectrometry of natural products: current, emerging and future technologies

“…Of particular relevance to the NP community is the increased sensitivity provided by implementing powerful ion optics with improved ion transmission in the development of sensitive and easy-to-use commercial high resolution mass spectrometers such as Q-TOFs (Quadrupole-Time of flight) with a single point lock mass internal calibration 26 , LTQ-Orbitrap hybrid and Fourier transform ion cyclotron (FT-ICR) 27, 28 . High resolution instruments are becoming necessary for NP identification by providing accurate mass measurements for the determination of chemical formula in addition to MS/MS spectra of compounds generating high confidence in structural elucidation.…”

“…One of the most relevant progresses in this field is the introduction of ultra-performance liquid chromatography (UPLC), leading to improvements in chromatographic peak resolution, sensitivity, separation speed, and spectral quality 32 . Examples of recent applications of LC - high resolution MS for NP analysis include dereplication of fungal metabolites 33 and a high-throughput analysis of phytochemicals in a plant extract 34 .…”