Beyond the paradigm: Combining mass spectrometry and nuclear magnetic resonance for metabolomics

Abstract

Metabolomics is undergoing tremendous growth and is being employed to solve a diversity of biological problems from environmental issues to the identification of biomarkers for human diseases. Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the analytical tools that are routinely, but separately, used to obtain metabolomics data sets due to their versatility, accessibility, and unique strengths. NMR requires minimal sample handling without the need for chromatography, is easily quantitative, and provides multiple means of metabolite identification, but is limited to detecting the most abundant metabolites (≥ 1 μM). Conversely, mass spectrometry has the ability to measure metabolites at very low concentrations (femtomolar to attomolar) and has a higher resolution (∼103-104) and dynamic range (∼103-104), but quantitation is a challenge and sample complexity may limit metabolite detection because of ion suppression. Consequently, liquid chromatography (LC) or gas chromatography (GC) is commonly employed in conjunction with MS, but this may lead to other sources of error. As a result, NMR and mass spectrometry are highly complementary, and combining the two techniques is likely to improve the overall quality of a study and enhance the coverage of the metabolome. While the majority of metabolomic studies use a single analytical source, there is a growing appreciation of the inherent value of combining NMR and MS for metabolomics. An overview of the current state of utilizing both NMR and MS for metabolomics will be presented.

Analysis of earthworm sublethal toxic responses to atrazine exposure using 1H nuclear magnetic resonance (NMR)‐based metabolomics

“…PCA and screening of metabolic shifts with atrazine exposure Averaged and individual PCA scores plots were constructed to investigate whether any differences between the unexposed control and atrazine-exposed earthworms existed [1,18] (Figure 1 and Supplemental Data, Figures S1 and S2, respectively). This method is commonly used in environmental metabolomics to screen for any differences within the broader dataset that can then be further investigated using more detailed analyses such as metabolite quantification [37,38,46]. In the PCA scores plot, we did not observe any significant separation (p > 0.05) between the atrazine-exposed earthworms and control along PC1 and PC2 (Supplemental Data, Figure S1).…”

Metabolomics reveal physiological changes in mayfly larvae (Neocloeon triangulifer) at ecological upper thermal limits

“…Therefore the contradicting metabolites are likely due to the lack of correlation in between the two analytical methods. However, it is necessary to conduct and combine both NMR and mass spectral data because of the diverse and complementary information it provides (Marshall and Powers, 2017). We tend interpret metabolites that either increased or decreased and not discuss in depth of the contradicting metabolites.…”

Ex-VivoEquine Cartilage Explant Osteoarthritis Model - A Metabolomics and Proteomics Study

“…Additional MS based metabolomics analysis of the culture media within this study may be beneficial as NMR and MS are complementary techniques and would therefore expand the number of identified/quantified metabolites, additionally identifying potential lipid and carbohydrate profiles of interest 9,38,43,102 . In order to confirm the differentially abundant proteins within this study, validation using an orthologous technique e.g.…”