This work was funded by the NSF Plant Genome Research Program grant IOS-1238812 and the Postdoctoral Fellowship in Biology IOS-1400818. The work was also funded by a Monsanto Graduate Student Fellowship to Katherine A. Sammons. The Fulbright African Researcher Scholars Program (2017-2018) is thanked for funding awarded to Nokwanda P. Makunga. We greatly appreciate the donation of a nanospray source from Jessica Prenni and the Proteomics and Metabolomics facility at Colorado State University.

1. Modifications to Nanospray Source for Leaf Spray MS
<ol>
	<li>Use a modified nanospray source for leaf spray MS. As no fluidic components are necessary for leaf spray MS, modify the source by removing the LC probe from the source.</li>
	<li>Assemble the leaf spray MS wire that will apply the voltage to the plant tissue with the appropriate pin for plugging into the source. Solder the pin to one end of an insulated wire; solder a clamp to the opposite end of the wire. 
	NOTE: The clamp (alligator clip type) may or may not have teeth. For small tissue, a clamp without teeth is preferred. An optional flex arm with a clamp may be added to the nanospray source to assist in positioning the plant tissue. Note that this protocol specifically describes how to perform leaf spray MS on a hybrid quadrupole ion trap mass analyzer MS system (see the Table of Materials); however, other MS systems may be altered to perform this technique6. Coupling leaf spray MS with a portable mass spectrometer real-time chemical analysis can be performed on-site without the need to transport the plant material to the laboratory19,20.</li>
	<li>Position an anti-static floor mat on the floor below the source to reduce the electrical discharge that may occur from the source when using high voltages.</li>
</ol>
2. Preparation of the MS System for Leaf Spray MS
<ol>
	<li>If the system has recently been in use, allow it to cool to the touch and remove any alternative source and the sweep cone. Attach the nanospray leaf spray MS source.</li>
	<li>Create a tune file with the appropriate ionization parameters set as follows: sheath, auxiliary, and sweep gas to 0; the spray voltage to 2 - 5 kV; the capillary temperature to 150 - 250 &#176;C; and the S-lens RF level to 50. Save the tune file with the desired parameters8,13. Optimize the voltage and temperature for the best ionization of the tissue and compound(s) of interest. 
	NOTE: Good starting points are 4 kV and 200 &#176;C.</li>
	<li>Make a method file including the leaf spray MS tune file with: positive and negative full MS; a resolution of 70,000; an AGC target of 1 x 106; a maximum IT of 200 ms; and the desired scan range m/z. Alternatively, use only 1 polarity.</li>
</ol>
3. Preparation of Instrument, Solvents, and Plant Tissue
NOTE: Always wear gloves, and do not use plant tissue that has been handled with bare hands. Otherwise, contaminant ions such as polyethylene glycol will dominate the spectra.
<ol>
	<li>Bring the plant tissues for the analysis to the same room as the MS system to allow for a rapid sampling.</li>
	<li>For plant tissue that does not have a naturally pointed tip, use a razor blade on a glass slide to cut a tapered point (Figure 2). Determine the amount of tissue needed for the analysis based on the instrument sensitivity, tissue type, and compound(s) of interest (e.g., a young S. tortuosum leaf that is ~5 mm in length).
	<ol>
		<li>Cut S. tortuosum leaves at 10 weeks post-germination into thin strips, each with a tapered end to form a point.</li>
	</ol>
	</li>
	<li>Use forceps to gently select the plant tissue at the end that will be clamped. Holding the tissue with forceps, carefully transfer it to the clamp. 
	CAUTION: Do not touch the instrument source if the voltage is on.</li>
	<li>Adjust the flexible arm and the wire with the clamp to position the tissue in line with the MS inlet so that the distance between the plant tissue and the ion inlet of the MS is 5 - 10 mm for the triple quadrupole (e.g., TSQ) and linear trap quadrupole (LTQ) and 10 - 50 mm for the ion trap mass analyzer (e.g., orbitrap)8.
	<ol>
		<li>Plug the opposite end of the wire into the source. If the first attempts produce a low signal intensity, move the plant tissue closer to the ion inlet (refer to the Discussion for optimization).</li>
	</ol>
	</li>
	<li>Load the method file; name the data file and set the file storage location. Then turn on the MS system by clicking Play and click on Start to begin acquiring data.</li>
	<li>Apply a solvent (e.g., methanol) using a pipet with a gel-loading tip to maximize the distance between the hands and the high voltage to protect the user. 
	NOTE: The solvent volume required depends on the size, dryness, and texture of the tissue, typically ~2 - 20 &#181;L. S. tortuosum leaves do not require any solvent to be added. Carefully apply the solvent and do not touch the instrument source when the voltage is on. Use LC-MS grade solvents and glassware that has been acid washed and is free of detergents. In some tissues, a signal may be observed without the addition of a solvent due to the natural water content of the plant tissue. However, a greater signal intensity and reduced S/N is typically achieved by applying a solvent to the tissue.</li>
	<li>Acquire data as long as the signal persists or until the adequate spectra have been collected, typically 30 - 60 s. If needed, apply additional solvent to maintain a high signal intensity for a longer amount of time. Stop the data acquisition and pause the MS system.</li>
	<li>Remove the tissue and wash the clamp with 100% methanol and a lint-free wipe. Clean the MS ion inlet after approximately 1 - 2 h of the acquisition by leaf spray MS according to the vendor&#39;s specifications. Also, clean the MS ion inlet between analyses of different tissue types.</li>
</ol>
4. Data Quality Assessment
<ol>
	<li>Open the data file and visually inspect the base peak mass chronogram. Check that the signal intensity is ~1.0 x 107 to 5.0 x 108. If the signal is lower, move the tissue closer to the ion inlet. If higher, the front end of the MS system will become dirty, so move the tissue further from the ion inlet.</li>
	<li>Based on the presence or absence of the ions of interest in the mass spectra produced, alter the parameters. 
	NOTE: The protocol can be paused here.</li>
</ol>
5. Tandem Mass Fragmentation
<ol>
	<li>Decide what ions are of interest for the tandem mass fragmentation (MS/MS); a mass spectra signal that is &#62; 1.0 x 105 is sufficient for the selection of ions for MS/MS.</li>
	<li>Make a new method file with an inclusion list of m/z out to 4 decimal places. Click on Global lists and Inclusion. Under properties of PRM, select the fragmentation energy [e.g., normalized collision energy (NCE) of 30 - 50 is a good range to start with] and other MS/MS parameters.
	<ol>
		<li>To obtain MS/MS data for mesembrine alkaloids, fragment the following ions, 276.1583 m/z, 290.1742 m/z, and 292.1897 m/z, at NCE 35. 
		NOTE: The MS/MS data acquisition can be performed immediately after the MS or at a later time. The same tissue can often remain clamped after a full MS and can be reused to acquire MS/MS data. However, if a respraying does not provide a sufficient signal, use a new tissue.</li>
	</ol>
	</li>
	<li>Load the MS/MS method file and a named data file. Turn on the MS system, and start acquiring data, adding a solvent if necessary. When adequate spectra have been collected, typically after 30 - 60 s, stop the acquisition.</li>
	<li>Collect fragmentation at many different energies when assigning fragment ions. 
	NOTE: Since leaf spray MS lacks a chromatographic separation, the fragmentation spectra are likely to contain many ions, and fragmenting at different energies will help bring clarity.</li>
</ol>
6. Putative Identifications by Accurate Mass and Tandem Mass Fragmentation
<ol>
	<li>Make putative identifications by referencing accurate mass measurements from publicly available metabolite databases such as Metlin21, Human Metabolome Database22, Mass Bank23, Lipid Maps24, National Institute of Standards and Technology MS Search25, ReSpect for Phytochemicals26, or GNPS27.</li>
	<li>As these databases are not exhaustive, perform an additional literature review on the plant species chemically characterized as necessary.</li>
	<li>Match fragmentation ions from leaf spray MS/MS to the aforementioned databases when MS/MS information is available, or to the literature. Alternatively, use a manual interpretation of MS/MS fragment ions or a fragmentation of an authentic standard performed by the direct injection or LC-MS/MS.</li>
</ol>
7. Data Analysis
<ol>
	<li>Convert the MS raw files to mzXML files with the msConvert tool from Proteowizard28.</li>
	<li>Use the XCMS software package implemented in R for peak picking. Use a direct infusion processing method for the leaf spray MS analysis. 
	NOTE: The well-annotated scripts used for data processing can be found at https://github.com/HegemanLab/Leaf-Spray-Code.</li>
	<li>To obtain semi-quantitative measurements, accounting for the experimental variability, normalize the intensity of each metabolite by the total ion current (TIC), as the leaf spray MS signal intensity can vary, in part due to slight variations in the positioning of the leaf in the source and the differences in leaf shape and size.</li>
	<li>Alternatively, use vendor-provided software for the data analysis or MZmine2 (to be found at http://mzmine.github.io/)29.</li>
</ol>

<ol>
	<li>Pitt, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Principles+and+applications+of+liquid+chromatography+-+mass+spectrometry+in+clinical+biochemistry.">Principles and applications of liquid chromatography - mass spectrometry in clinical biochemistry.</a> The Clinical Biochemist Reviews. 30 (1), 19-34 (2009).</li><li>Cooks, R. G., Ouyang, Z., Takats, Z., Wiseman, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+technologies.+Ambient+mass+spectrometry.">Detection technologies. Ambient mass spectrometry.</a> Science. 311 (5767), 1566-1570 (2006).</li><li>Kim, H. K., Verpoorte, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sample+preparation+for+plant+metabolomics.">Sample preparation for plant metabolomics.</a> Phytochemical Analysis. 21 (1), 4-13 (2010).</li><li>Takats, Z., Wiseman, J. M., Gologan, B., Cooks, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+spectrometry+sampling+under+ambient+conditions+with+desorption+electrospray+ionization.">Mass spectrometry sampling under ambient conditions with desorption electrospray ionization.</a> Science. 306 (5695), 471-473 (2004).</li><li>Liu, J., Wang, H., Cooks, R. G., Ouyang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leaf+spray:+direct+chemical+analysis+of+plant+material+and+living+plants+by+mass+spectrometry.">Leaf spray: direct chemical analysis of plant material and living plants by mass spectrometry.</a> Analytical Chemistry. 83 (20), 7608-7613 (2011).</li><li>Chan, S. L. -. F., Wong, M. Y. -. M., Tang, H. -. W., Che, C. -. M., Ng, K. -. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-spray+ionization+mass+spectrometry+for+raw+herb+analysis.">Tissue-spray ionization mass spectrometry for raw herb analysis.</a> Rapid Communications in Mass Spectrometry. 25 (19), 2837-2843 (2011).</li><li>Wang, H., Liu, J., Cooks, R. G., Ouyang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Paper+spray+for+direct+analysis+of+complex+mixtures+using+mass+spectrometry.">Paper spray for direct analysis of complex mixtures using mass spectrometry.</a> Angewandte Chemie International Edition. 49 (5), 877-880 (2010).</li><li>Liu, J., Wang, H., Cooks, R. G., Ouyang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leaf+spray:+Direct+chemical+analysis+of+plant+material+and+living+plants+by+mass+spectrometry.">Leaf spray: Direct chemical analysis of plant material and living plants by mass spectrometry.</a> Analytical Chemistry. 83 (20), 7608-7613 (2011).</li><li>Malaj, N., Ouyang, Z., Sindona, G., Cooks, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+pesticide+residues+by+leaf+spray+mass+spectrometry.">Analysis of pesticide residues by leaf spray mass spectrometry.</a> Analytical Methods. 4 (7), 1913-1919 (2012).</li><li>Snyder, D. T., Schilling, M. C., Hochwender, G., Kaufman, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analytical+methods+profiling+phenolic+glycosides+in+Populus+deltoides+and+Populus+grandidentata+by+leaf+spray+ionization+tandem+mass+spectrometry.">Analytical methods profiling phenolic glycosides in Populus deltoides and Populus grandidentata by leaf spray ionization tandem mass spectrometry.</a> Analytical Methods. 7 (3), 870-876 (2015).</li><li>Falcone, C. E., Cooks, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+recognition+of+emerald+ash+borer+infestation+using+leaf+spray+mass+spectrometry.">Molecular recognition of emerald ash borer infestation using leaf spray mass spectrometry.</a> Rapid Communications in Mass Spectrometry. 30 (11), 1304-1312 (2016).</li><li>Liu, J., Gu, Z., Yao, S., Zhang, Z., Chen, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+analysis+of+Callicarpa+L.+using+direct+spray+ionization+mass+spectrometry.">Rapid analysis of Callicarpa L. using direct spray ionization mass spectrometry.</a> Journal of Pharmaceutical and Biomedical Analysis. 124, 93-103 (2016).</li><li>Freund, D. M., Martin, A. C., Cohen, J. D., Hegeman, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+detection+of+surface+localized+specialized+metabolites+from+Glycyrrhiza+lepidota+(American+licorice)+by+leaf+spray+mass+spectrometry.">Direct detection of surface localized specialized metabolites from Glycyrrhiza lepidota (American licorice) by leaf spray mass spectrometry.</a> Planta. 247 (1), 267-275 (2018).</li><li>Smith, M. T., Crouch, N. R., Gericke, N., Hirst, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Psychoactive+constituents+of+the+genus+Sceletium+N.E.Br.+and+other+Mesembryanthemaceae:+a+review.">Psychoactive constituents of the genus Sceletium N.E.Br. and other Mesembryanthemaceae: a review.</a> Journal of Ethnopharmacology. 50 (3), 119-130 (1996).</li><li>Gerickea, N., Viljoen, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sceletium-a+review+update.">Sceletium-a review update.</a> Journal of Ethnopharmacology. 119 (3), 653-663 (2008).</li><li>Terburg, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+effects+of+Sceletium+tortuosum+(Zembrin),+a+dual+5-HT+reuptake+and+PDE4+inhibitor,+in+the+human+amygdala+and+its+connection+to+the+hypothalamus.">Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala and its connection to the hypothalamus.</a> Neuropsychopharmacology. 38 (13), 2708-2716 (2013).</li><li>Coetzee, D. D., L&#243;pez, V., Smith, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-mesembrine+Sceletium+extract+(TrimesemineTM)+is+a+monoamine+releasing+agent,+rather+than+only+a+selective+serotonin+reuptake+inhibitor.">High-mesembrine Sceletium extract (TrimesemineTM) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor.</a> Journal of Ethnopharmacology. 177, 111-116 (2016).</li><li>Shikanga, E. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+permeation+of+mesembrine+alkaloids+from+Sceletium+tortuosum+across+porcine+buccal,+sublingual,+and+intestinal+mucosa.">In vitro permeation of mesembrine alkaloids from Sceletium tortuosum across porcine buccal, sublingual, and intestinal mucosa.</a> Planta Medica. 78 (3), 260-268 (2012).</li><li>Pulliam, C. J., Bain, R. M., Wiley, J. S., Ouyang, Z., Cooks, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+spectrometry+in+the+home+and+garden.">Mass spectrometry in the home and garden.</a> Journal of The American Society for Mass Spectrometry. 26 (2), 224-230 (2015).</li><li>Lawton, Z. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analytical+validation+of+a+portable+mass+spectrometer+featuring+interchangeable,+ambient+ionization+sources.">Analytical validation of a portable mass spectrometer featuring interchangeable, ambient ionization sources.</a> Journal of the American Society for Mass Spectrometry. 28 (6), 1048-1059 (2017).</li><li>. GNPS Available from: <a target="_blank" href="https://gnps.ucsd.edu/">https://gnps.ucsd.edu/</a> (2018)</li><li>Chambers, M. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+cross-platform+toolkit+for+mass+spectrometry+and+proteomics.">A cross-platform toolkit for mass spectrometry and proteomics.</a> Nature Biotechnology. 30 (10), 918-920 (2012).</li><li>Pluskal, T., Castillo, S., Villar-Briones, A., Ore, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MZmine2:+modular+framework+for+processing,+visualizing,+and+analyzing+mass+spectrometry-based+molecular+profile+data.">MZmine2: modular framework for processing, visualizing, and analyzing mass spectrometry-based molecular profile data.</a> BMC Bioinformatics. 11, 395 (2010).</li><li>Meyer, G. M. J., Wink, C. S. D., Zapp, J., Maurer, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GC-MS,+LC-MS(n),+LC-high+resolution-MS(n),+and+NMR+studies+on+the+metabolism+and+toxicological+detection+of+mesembrine+and+mesembrenone,+the+main+alkaloids+of+the+legal+high+&amp;#34;Kanna&amp;#34;+isolated+from+Sceletium+tortuosum.">GC-MS, LC-MS(n), LC-high resolution-MS(n), and NMR studies on the metabolism and toxicological detection of mesembrine and mesembrenone, the main alkaloids of the legal high &amp;#34;Kanna&amp;#34; isolated from Sceletium tortuosum.</a> Analytical and Bioanalytical Chemistry. 407 (3), 761-778 (2015).</li><li>Zhang, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+detection+of+polyhydroxylated+alkaloids+in+mulberry+using+leaf+spray+mass+spectrometry.">Rapid detection of polyhydroxylated alkaloids in mulberry using leaf spray mass spectrometry.</a> Analytical Methods. 5 (10), 2455-2460 (2013).</li><li>Pereira, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+screening+of+agrochemicals+by+paper+spray+ionization+and+leaf+spray+mass+spectrometry:+which+technique+is+more+appropriate?.">Rapid screening of agrochemicals by paper spray ionization and leaf spray mass spectrometry: which technique is more appropriate?.</a> Analytical Methods. 8, 6023-6029 (2016).</li><li>Zhang, J. I., Li, X., Cooks, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+analysis+of+steviol+glycosides+from+Stevia+leaves+by+ambient+ionization+mass+spectrometry+performed+on+whole+leaves.">Direct analysis of steviol glycosides from Stevia leaves by ambient ionization mass spectrometry performed on whole leaves.</a> The Analyst. 137 (13), 3091-3098 (2012).</li><li>Freund, D. M., Hegeman, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+stable+isotope-enabled+mass+spectrometry-based+plant+metabolomics.">Recent advances in stable isotope-enabled mass spectrometry-based plant metabolomics.</a> Current Opinion in Biotechnology. 43, 41-48 (2017).</li><li>Wurtzel, E. T., Kutchan, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+metabolism,+the+diverse+chemistry+set+of+the+future.">Plant metabolism, the diverse chemistry set of the future.</a> Science. 353 (6305), 1232-1236 (2016).</li></ol>

The authors have nothing to disclose.

The successful use of this protocol relies on the optimization of various steps for the plant species, tissue type, and target compound(s) of interest. The parameters described in the protocol provide a good starting point. The following experimental decisions need to be made and tested: whether or not to use (1) cut or uncut tissue and (2) solvent or no solvent, (3) what solvent to use and in what volume, (4) what the distance of tissue from the ion inlet should be, and (5) the voltage amplitude. The goal of optimizatio...

Plants contain a wide range of small molecules with diverse chemical properties. MS is a powerful technique for analyzing plant compounds because it can provide elemental compositions with a high sensitivity and specificity for the detection and identification of metabolites1. Most commonly, MS is performed on solvent-extracted samples, which are separated by chromatography prior to the MS analysis1. However, the use of liquid chromatography (LC) requires lengthy analysis times and is often associated with an extensive sample preparation1. In contrast, direct chemical analysis of intact tissues that circumvents chromatography is a very rapid technique, requiring minimal sample preparation2. Thus, in instances where chromatographic steps can be forgone, a direct chemical analysis can be highly advantageous.
Typical LC-MS for natural products and metabolomics research relies on lengthy bulk extractions of dried or frozen plant materials containing multiple tissues and cell types3. Alternatively, direct chemical analysis, such as the MS detection of metabolites from plant tissue, can isolate cell types and avoid preparation artifacts4. Leaf spray MS, also referred to as tissue-spray5,6, is a direct ambient ionization MS technique, which requires essentially no sample preparation5,7. Leaf spray MS is closely related to paper spray MS, an ambient ionization technique with characteristics of electrospray ionization that allows for the detection of analytes that are deposited onto paper7. In spite of the name, leaf spray MS is applicable to various types of plant tissues, not just leaves, and has been demonstrated on fruit, seeds, roots, floral tissues, and tubers, among others6,8,9,10,11,12. The technique facilitates the ionization of endogenous phytochemicals directly from the plant materials into the mass spectrometer for detection8. Leaf spray MS can also provide information about the spatial distribution of chemicals in different tissue types in plants13. When leaf spray MS is compared with solvent extraction and LC-MS, the results suggest leaf spray MS allows for the rapid detection of surface metabolites from unique cell types such as trichomes13. Figure 1 illustrates the leaf spray MS experimental set-up. Direct electrospray ionization occurs after only minor source modifications. A high voltage is applied to the plant tissue via a metal clamp, producing a spray of highly charged droplets forming a Taylor cone that carries the ions to the ion inlet of the MS. Electrospray ionization occurs from the natural liquid of the plant or from the solvent applied to the plant surface. A pointed tip on the tissue facilitates the electrospray and can be naturally occurring or created by cutting.
Leaf spray MS is a fast method for the qualitative and semi-quantitative analysis of intact plant tissues that have found utility for a wide variety of applications. For example, the technique has been used to detect endogenous compounds to distinguish related species, and even to evaluate changes in the same species grown under different conditions. Previous studies have shown this approach by measuring metabolites in beautyberry (Callicarpa L.)12 and American ginseng (Panax quinquefolium L.)6. In the latter example, ginsenosides, amino acids, and oligosaccharides could be detected after wetting raw ginseng tissue. Wild and cultivated American ginseng were differentiated from tuber slices6. Ginseng tuber integrity was preserved succeeding leaf spray MS, which allowed for a subsequent morphological and microscopic inspection6. Furthermore, exogenous compounds on plant samples can also be detected. A number of pesticides (acetamiprid, diphenylamine, imazalil, linuron, and thiabendazole) have been detected on peel or pulp of fruits and vegetables9. While these studies and many others have shown the utility of leaf spray MS for various specific purposes, a detailed protocol has not been previously reported.
Here, the protocol description will not focus on the optimization of the method for a specific tissue or compound. Rather, the detection of mesembrine alkaloids from Sceletium tortuosum (L.) N.E.Br. (Aizoaceae) is used as an example to discuss the necessary optimization measures that should be taken when setting up a leaf spray MS experiment for a species, tissue, or compound(s) for the first time. S. tortuosum is a succulent endemic to the semi-arid Karroo region of South Africa. A traditional medicine of the San and Khoi Khoi peoples, it was used for appetite and thirst suppression as well as for its psychotropic and analgesic effects14,15. Currently, standardized extracts are used for the treatment of neuropsychiatric and neuropsychological disorders16,17. The primary compounds of interest include the alkaloid mesembrine and its derivatives, many of which are also found in related Sceletium species15. Both wild and cultivated populations of S. tortuosum have variable concentrations of mesembrine alkaloids, thus presenting a quality control challenge18. A method for the rapid detection of mesembrine alkaloids, such as leaf spray MS, may be useful in monitoring Sceletium products. Because previously, there had been no detailed visual experimental protocol for the leaf spray MS technique, we will illustrate the method using the example of S. tortuosum, and the following is described: the modification of a nanospray source, the selection and preparation of the plant tissues, the acquisition of the data, the interpretation of the results, and the optimization of the MS parameters.

<table><tbody><tr><td>Conn Pin</td><td>Digi-Key elctronics</td><td>WM2563CT-ND</td><td>pin will insert into Thermo Scientific source to provide voltage</td></tr><tr><td>small clamp</td><td>Digi-Key elctronics</td><td>314-1018-ND</td><td>CLIP MICRO ALLIGATOR COPPER 5A</td></tr><tr><td>large clamp</td><td>Digi-Key elctronics</td><td>290-1951-ND</td><td>ALLIGATOR CLIP NARROW NICKLE 5A</td></tr><tr><td>Heat shrink</td><td>Digi-Key elctronics</td><td>Q2Z1-KIT-ND</td><td>to cover soldering joints</td></tr><tr><td>NSI source Nanospray Ion Source</td><td>Thermo scientific</td><td>NA</td><td>Another brand will work if you are not using a Thermo instrument</td></tr><tr><td>Q Exactive- hybrid quadrupole Orbitrap</td><td>Thermo scientific</td><td>NA</td><td>Another brand will work if you are not using a Thermo instrument</td></tr><tr><td>Tune Software</td><td>Thermo scientific</td><td></td><td>Another brand will work if you are not using a Thermo instrument</td></tr><tr><td>Xcalibur Software</td><td>Thermo scientific</td><td></td><td></td></tr><tr><td>Plant of interest - &lt;em&gt;S. tortousum&lt;/em&gt;</td><td></td><td></td><td></td></tr></tbody></table>

leaf spray mass spectrometry: a rapid ambient ionization technique to directly assess metabolites from plant tissues

Plants produce thousands of small molecules that are diverse in their chemical properties. Mass spectrometry (MS) is a powerful technique for analyzing plant metabolites because it provides molecular weights with high sensitivity and specificity. Leaf spray MS is an ambient ionization technique where plant tissue is used for direct chemical analysis via electrospray, eliminating chromatography from the process. This approach to sampling metabolites allows for a wide range of chemical classes to be detected simultaneously from intact plant tissues, minimizing the amount of sample preparation needed. When used with a high-resolution, accurate mass MS, leaf spray MS facilitates the rapid detection of metabolites of interest. It is also possible to collect tandem mass fragmentation data with this technique to facilitate a compound identification. The combination of accurate mass measurements and fragmentation is beneficial in confirming compound identities. The leaf spray MS technique requires only minor modifications to a nanospray ionization source and is a useful tool to further expand the capabilities of a mass spectrometer. Here, fresh leaf tissue from Sceletium tortuosum (Aizoaceae), a traditional medicinal plant from South Africa, is analyzed; numerous mesembrine alkaloids are detected with leaf spray MS.

At 10 weeks post-germination, freshly collected greenhouse-grown S. tortuosum leaves were analyzed by leaf spray MS. The experimental workflow for detecting metabolites from S. tortuosum leaves using leaf spray MS is illustrated in Figure 2. A leaf was selected, cut into a thin strip with a tapered end to form a point, and clamped with the leaf spray MS wire clamp apparatus. The plant tissue was positioned ~30 mm from the ion inlet and in li...

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Leaf Spray Mass Spectrometry: A Rapid Ambient Ionization Technique to Directly Assess Metabolites from Plant Tissues

Leaf spray mass spectrometry is a direct chemical analysis technique that minimizes the sample preparation and eliminates chromatography, allowing for the rapid detection of small molecules from plant tissues.

Plants produce thousands of small molecules that are diverse in their chemical properties. Mass spectrometry (MS) is a powerful technique for analyzing ...

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Research

JoVE Journal

Biochemistry

8.6K Views.  University of Minnesota. Spectrometrie van de massa van de spray blad is een directe analyse van de chemische techniek die minimaliseert de bereiding van de monsters en elimineert chromatografie, rekening houdend met de snelle detectie van kleine moleculen uit plantaardige weefsels.

Video: Leaf Spray Mass Spectrometry: A Rapid Ambient Ionization Technique to Directly Assess Metabolites from Plant Tissues

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS)

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first separated into polar and non-polar fractions by a liquid-liquid phase extraction, and partially purified to facilitate downstream analysis. Both aqueous (polar metabolites) and organic (non-polar metabolites) phases of the initial extraction are processed to survey a broad range of metabolites. Metabolites are separated by different liquid chromatography methods based upon their partition properties. In this method, we present microflow ultra-performance (UP)LC methods, but the protocol is scalable to higher flows and lower pressures. Introduction into the mass spectrometer can be through either general or compound optimized source conditions. Detection of a broad range of ions is carried out in full scan mode in both positive and negative mode over a broad m/z range using high resolution on a recently calibrated instrument. Label-free differential analysis is carried out on bioinformatics platforms. Applications of this approach include metabolic pathway screening, biomarker discovery, and drug development.

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry UPLC-HRMS

Untargeted metabolomics provides a hypothesis generating snapshot of a metabolic profile. This protocol will demonstrate the extraction and analysis of metabolites from cells, serum, or tissue. A range of metabolites are surveyed using liquid-liquid phase extraction, microflow ultraperformance liquid chromatography/high-resolution mass spectrometry (UPLC-HRMS) coupled to differential analysis software.

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first ...

Chemistry

Rapid High-throughput Species Identification of Botanical Material Using Direct Analysis in Real Time High Resolution Mass Spectrometry

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, and that these chemical fingerprints can be used for plant species identification. The mass spectral data can be acquired rapidly and in a high throughput manner without the need for sample extraction, derivatization or pH adjustment steps. The use of this technique bypasses challenges presented by more conventional techniques including lengthy chromatography analysis times and resource intensive methods. The high throughput capabilities of the direct analysis in real time-high resolution mass spectrometry protocol, coupled with multivariate statistical analysis processing of the data, provide not only class characterization of plants, but also yield species and varietal information. Here, the technique is demonstrated with two psychoactive plant products, Mitragyna speciosa (Kratom) and Datura (Jimsonweed), which were subjected to direct analysis in real time-high resolution mass spectrometry followed by statistical analysis processing of the mass spectral data. The application of these tools in tandem enabled the plant materials to be rapidly identified at the level of variety and species.

A method for species identification of botanical material by direct analysis in real time-high resolution mass spectrometry and multivariate statistical analysis is presented.

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, ...

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

Fizzy extraction is a new laboratory technique for analysis of volatile and semivolatile compounds. A carrier gas is dissolved in the liquid sample by applying overpressure and stirring the sample. The sample chamber is then decompressed. The analyte species are liberated to the gas phase due to effervescence.

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to ...

Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to characterize. However, to understand the thermodynamic and kinetic controls on greenhouse gas (carbon dioxide [CO2] and methane [CH4]) production resulting from the decomposition of NOM, a molecular-level characterization coupled with microbial proteome analyses is necessary. Further, climate and environmental changes are expected to perturb natural ecosystems, potentially upsetting complex interactions that influence both the supply of organic matter substrates and the microorganisms performing the transformations. A detailed molecular characterization of the organic matter, microbial proteomics, and the pathways and transformations by which organic matter is decomposed will be necessary to predict the direction and magnitude of the effects of environmental changes. This article describes a methodological throughput for comprehensive metabolite characterization in a single sample by direct injection Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), gas chromatography mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography mass spectrometry (LC-MS), and proteomics analysis. This approach results in a fully-paired dataset which improves statistical confidence for inferring pathways of organic matter decomposition, the resulting CO2 and CH4 production rates, and their responses to environmental perturbation. Herein we present results of applying this method to NOM samples collected from peatlands; however, the protocol is applicable to any NOM sample (e.g., peat, forested soils, marine sediments, etc.).

This protocol describes a single throughput for complementary analytical and omics techniques culminating in a fully-paired characterization of natural organic matter and microbial proteomics in different ecosystems. This approach permits robust comparisons for identifying metabolic pathways and transformations important for describing greenhouse gas production and predicting responses to environmental change.

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to ...

Environment

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form loose callus on Murashige and Skoog (MS) basal media with the plant hormones 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg L-1) and kinetin (KT, 0.1 mg L-1). Callus formed after 3 or 4 rounds of subculturing, each lasting 28 days. Loose callus (about 3 g) was then inoculated into B5 liquid media containing the same plant hormones and was cultured in a shaking incubator (120 rpm) in the dark at 25 &#177; 1 &#176;C. After 3&#8722;4 subcultures, a cell suspension derived from tea leaf was established at a subculture ratio ranging between 1:1 and 1:2 (suspension mother liquid: fresh medium). Using this platform, six insecticides (5 &#181;g mL-1 each thiamethoxam, imidacloprid, acetamiprid, imidaclothiz, dimethoate, and omethoate) were added into the tea leaf-derived cell suspension culture. The metabolism of the insecticides was tracked using liquid chromatography and gas chromatography. To validate the usefulness of the tea cell suspension culture, the metabolites of thiamethoxan and dimethoate present in treated cell cultures and intact plants were compared using mass spectrometry. In treated tea cell cultures, seven metabolites of thiamethoxan and two metabolites of dimethoate were found, while in treated intact plants, only two metabolites of thiamethoxam and one of dimethoate were found. The use of a cell suspension simplified the metabolic analysis compared to the use of intact tea plants, especially for a difficult matrix such as tea.

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea Camellia Sinensis L. Leaves

This work presents a protocol for establishing a cell suspension culture derived from tea (Camellia sinensis L.) leaves that can be used to study the metabolism of external compounds that can be taken up by the whole plant, such as insecticides.

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form ...

Investigation of Xenobiotics Metabolism In Salix alba Leaves via Mass Spectrometry Imaging

The method presented uses mass spectrometry imaging (MSI) to establish the metabolic profile of S. alba leaves when exposed to xenobiotics. Using a non-targeted approach, plant metabolites and xenobiotics of interest are identified and localized in plant tissues to uncover&#160;specific distribution patterns. Then, in silico prediction of potential metabolites (i.e., catabolites and conjugates) from the identified xenobiotics is performed. When a xenobiotic metabolite is located in the tissue, the type of enzyme involved in its alteration by the plant is recorded. These results were used to describe different types of biological reactions occurring in S. alba leaves in response to xenobiotic accumulation in the leaves. The metabolites were predicted in two generations, allowing the documentation of successive biological reactions to transform xenobiotics in the leaf tissues.

Investigation of Xenobiotics Metabolism In Salix alba Leaves via Mass Spectrometry Imaging

This method uses mass spectrometry imaging (MSI) to understand metabolic processes in S. alba leaves when exposed to xenobiotics. The method allows the spatial localization of compounds of interest and their predicted metabolites within specific, intact tissues.

The method presented uses mass spectrometry imaging (MSI) to establish the metabolic profile of S. alba leaves when exposed to xenobiotics. Using a ...

Untargeted Liquid Chromatography-Mass Spectrometry-Based Metabolomics Analysis of Wheat Grain

Understanding the interactions between genes, the environment and management in agricultural practice could allow more accurate prediction and management of product yield and quality. Metabolomics data provides a read-out of these interactions at a given moment in time and is informative of an organism&#39;s biochemical status. Further, individual metabolites or panels of metabolites can be used as precise biomarkers for yield and quality prediction and management. The plant metabolome is predicted to contain thousands of small molecules with varied physicochemical properties that provide an opportunity for a biochemical insight into physiological traits and biomarker discovery. To exploit this, a key aim for metabolomics researchers is to capture as much of the physicochemical diversity as possible within a single analysis. Here we present a liquid chromatography-mass spectrometry-based untargeted metabolomics method for the analysis of field-grown wheat grain. The method uses the liquid chromatograph quaternary solvent manager to introduce a third mobile phase and combines a traditional reversed-phase gradient with a lipid-amenable gradient. Grain preparation, metabolite extraction, instrumental analysis and data processing workflows are described in detail. Good mass accuracy and signal reproducibility were observed, and the method yielded approximately 500 biologically relevant features per ionization mode. Further, significantly different metabolite and lipid feature signals between wheat varieties were determined.

A method for the untargeted analysis of wheat grain metabolites and lipids is presented. The protocol includes an acetonitrile metabolite extraction method and reversed phase liquid chromatography-mass spectrometry methodology, with acquisition in positive and negative electrospray ionization modes.

Understanding the interactions between genes, the environment and management in agricultural practice could allow more accurate prediction and management ...

Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI Mass Spectrometry

Ambient ionization methods in mass spectrometry allow analytical investigations to be performed directly on a tissue or biofilm under native-like experimental conditions. Laser ablation electrospray ionization (LAESI) is one such development and is particularly well-suited for the investigation of water-containing specimens. LAESI utilizes a mid-infrared laser beam (2.94 &mu;m wavelength) to excite the water molecules of the sample. When the ablation fluence threshold is exceeded, the sample material is expelled in the form of particulate matter and these projectiles travel to tens of millimeters above the sample surface. In LAESI, this ablation plume is intercepted by highly charged droplets to capture a fraction of the ejected sample material and convert its chemical constituents into gas-phase ions. A mass spectrometer equipped with an atmospheric-pressure ion source interface is employed to analyze and record the composition of the released ions originating from the probed area (pixel) of the sample. A systematic interrogation over an array of pixels opens a way for molecular imaging in the microprobe analysis mode. A unique aspect of LAESI mass spectrometric imaging is depth profiling that, in combination with lateral imaging, enables three-dimensional (3D) molecular imaging. With current lateral and depth resolutions of ~100 &mu;m and ~40 &mu;m, respectively, LAESI mass spectrometric imaging helps to explore the molecular structure of biological tissues. Herein, we review the major elements of a LAESI system and provide guidelines for a successful imaging experiment.

Laser ablation electrospray ionization (LAESI) is an atmospheric-pressure ion source for mass spectrometry. In the imaging mode, a mid-infrared laser probes the distributions of molecules across a tissue section or a biofilm. This technique presents a new approach for diverse bioanalytical studies carried out under native experimental conditions.

Ambient ionization methods in mass spectrometry allow analytical investigations to be performed directly on a tissue or biofilm under native-like ...

Biology

Primary Organ Identification in Medicinal Plants Using 13C6&#45;Glucose Labeling

13C6&#45;Glucose Labeling Associated with LC&#45;MS&#58; Identification of Plant Primary Organs in Secondary Metabolite Synthesis

This paper presents a novel and efficient method for certifying primary organs involved in secondary metabolite synthesis. As the most important secondary metabolite in Parispolyphylla var. yunnanensis (Franch.) Hand. -Mzt. (PPY), Paris saponin (PS) has a variety of pharmacological activities and PPY is in increasing demand. This study established leaf, rhizome, and stem-vascular-bundle 13C6-Glucose feeding and non-feeding four treatments to precisely certify the primary organs involved in Paris saponins VII (PS VII) synthesis. By combining liquid chromatography-mass spectrometry (LC-MS), the 13C/12C ratios of leaf, rhizome, stem, and root in different treatments were quickly and accurately calculated, and four types of PS isotopic ion peak(M&#8722;) ratios were found: (M+1) &#8722;/M&#8722;, (M+2) &#8722;/M&#8722;, (M+3) &#8722;/M&#8722; and (M+4) &#8722;/M&#8722;. The results showed that the ratio of 13C/12C in the rhizomes of the stem-vascular-bundle and rhizome feeding treatments was significantly higher than that in the non-feeding treatment. Compared to the non-feeding treatment, the ratio of PS VII molecules (M+2) &#8722;/M&#8722; in the leaves increased significantly under leaf and stem-vascular-bundle feeding treatments. Simultaneously, compared to the non-feeding treatment, the ratio of PS VII molecules (M+2) &#8722;/M&#8722; in the leaves under rhizome treatment showed no significant difference. Furthermore, the ratio of PS VII molecules (M+2) &#8722;/M&#8722; in the stem, root, and rhizome showed no differences among the four treatments. Compared to the non-feeding treatment, the ratio of the Paris saponin II (PS II) molecule (M+2) &#8722;/M&#8722; in leaves under leaf feeding treatment showed no significant difference, and the (M+3) &#8722;/M&#8722; ratio of PS II molecules in leaves under leaf feeding treatment were lower. The data confirmed that the primary organ for the synthesizing of PS VII is the leaves. It lays the foundation for future identification of the primary organs and pathways involved in the synthesis of secondary metabolites in medicinal plants.

Author Spotlight: Plant Primary Organs Profiling Using 13C6&#45;Glucose Labeling and LC&#45;MS

The developed method of 13C6-Glucose labeling combined with liquid chromatography high-resolution mass spectrometry is versatile and lays the foundation for future studies on the primary organs and pathways involved in the synthesis of secondary metabolites in medicinal plants, as well as the comprehensive utilization of these secondary metabolites.

This paper presents a novel and efficient method for certifying primary organs involved in secondary metabolite synthesis. As the most important secondary ...

MALDI-Mass Spectrometric Imaging for the Investigation of Metabolites in Medicago truncatula Root Nodules

Most techniques used to study small molecules, such as pharmaceutical drugs or endogenous metabolites, employ tissue extracts which require the homogenization of the tissue of interest that could potentially cause changes in the metabolic pathways being studied1. Mass spectrometric imaging (MSI) is a powerful analytical tool that can provide spatial information of analytes within intact slices of biological tissue samples1-5. This technique has been used extensively to study various types of compounds including proteins, peptides, lipids, and small molecules such as endogenous metabolites. With matrix-assisted laser desorption/ionization (MALDI)-MSI, spatial distributions of multiple metabolites can be simultaneously detected. Herein, a method developed specifically for conducting untargeted metabolomics MSI experiments on legume roots and root nodules is presented which could reveal insights into the biological processes taking place. The method presented here shows a typical MSI workflow, from sample preparation to image acquisition, and focuses on the matrix application step, demonstrating several matrix application techniques that are useful for detecting small molecules. Once the MS images are generated, the analysis and identification of metabolites of interest is discussed and demonstrated. The standard workflow presented here can be easily modified for different tissue types, molecular species, and instrumentation.

MALDI-Mass Spectrometric Imaging for the Investigation of Metabolites in Medicago truncatula Root Nodules

Mass spectrometric imaging (MSI) is a powerful tool that can be used to discover and identify various chemical species in intact tissues, preserving the compounds in their native environments, which can provide new insights into biological processes. Herein a MSI method developed for the analysis of small molecules is described.&#160;

Leaf Spray Mass Spectrometry: A Rapid Ambient Ionization Technique to Directly Assess Metabolites from Plant Tissues

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