DESI MS, has been successfully employed for the analysis of molecules from a wide variety of surfaces without prior sample treatment. The efficiency of DESI MS relies on various parameters. However, those that critically affect the ionization of biological samples include: the solvent system and the sample or sample spotting surfaces. These parameters gain unequivocal dominance specially whilst dealing with sensitive and intricate biological samples. This review is meant to capture the attention of the DESI-MS researchers towards the crucial role of the solvent and sample spotting surfaces for successful biological DESI-MS. This review highlights these parameters as the backbone of the breakthroughs achieved in the analysis of biological materials of plant, bacterial, animal and human origins. © 2016 Elsevier B.V..

Pradeep Thalappil

Department Of Chemistry

Biological materials

ionization

Mass spectrometry

Solvents

Substrates

Analytes

Biological samples

DESI MS

MOLECULAR IMPRINTING

Solvent system

Electrospray ionization

Acetone

acetonitrile

ALPRAZOLAM

AMETRYN

Ascorbic acid

Atrazine

BROMOPHYCOLIDES

BROMOPHYCOLIDES A

BROMOPHYCOLIDES B

CANNABIDIOL

chloroform

citric acid

Dichloromethane

dronabinol

ENILCONAZOLE

Hexane

HYDROCODONE

illicit drug

MALIC ACID

Methanol

n,n dimethylformamide

natural product

PARACETAMOL

politef

PREDNISONE

SPINOSAD

THIRAM

TIABENDAZOLE

unclassified drug

unindexed drug

Water

BLADDER TUMOR

COLORECTAL CARCINOMA

DESORPTION ELECTROSPRAY IONIZATION MASS SPECTROMETRY

diagnostic value

Human

LIVER METASTASIS

MASS SPECTROMETER

matrix assisted laser desorption ionization time of flight mass spectrometry

nonhuman

PHYTOCHEMISTRY

priority journal

Process optimization

review

SEMINOMA

Solvent effect

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

TrAC - Trends in Analytical Chemistry

Rohitukine, a chromone alkaloid, possesses anti-inflammatory, anti-cancer and immuno-modulatory properties. It has been reported from four species, belonging to the families, Meliaceae and Rubiaceae. Stem bark of Dysoxylum binectariferum (Meliaceae) accumulates the highest amount of rohitukine (3-7% by dry weight). In this study, we examine the spatial and temporal distribution of rohitukine and related compounds during various stages of seed development in D. binectariferum using desorption electrospray ionization mass spectrometry imaging (DESI MSI). Rohitukine (m/z 306.2) accumulation increased from early seed development to seed maturity stage. The spatial distribution of rohitukine was largely restricted to the cotyledonary tissue followed by the embryo and least in the seed coat. Besides rohitukine, rohitukine acetate (m/z 348.2) and glycosylated rohitukine (m/z 468.2) were also detected, both through mass fragmentation and exact mass analysis through Orbitrap mass spectrometry. These results indicate a dynamic pattern of chromane alkaloid accumulation through seed development in D. binectariferum. © 2015 Elsevier Ltd. All rights reserved.

Phytochemistry

Ambient ionization mass spectrometry imaging of Rohitukine, a chromone anti-cancer alkaloid, during seed development in Dysoxylum binectariferum Hook.f (Meliaceae)

The analytical performance and a suggested mechanism for zero volt paper spray using chromatography paper are presented. A spray is generated by the action of the pneumatic force of the mass spectrometer (MS) vacuum at the inlet. Positive and negative ion signals are observed, and comparisons are made with standard kV paper spray (PS) ionization and nanoelectrospray ionization (nESI). While the range of analytes to which zero volt PS is applicable is very similar to kV PS and nESI, differences in the mass spectra of mixtures are interpreted in terms of the more significant effects of analyte surface activity in the gentler zero volt experiment than in the other methods due to the significantly lower charge. The signal intensity of zero volt PS is also lower than in the other methods. A Monte Carlo simulation based on statistical fluctuation of positive and negative ions in solution has been implemented to explain the production of ions from initially uncharged droplets. Uncharged droplets first break up due to aerodynamics forces until they are in the 2-4 μm size range and then undergo Coulombic fission. A model involving statistical charge fluctuations in both phases predicts detection limits similar to those observed experimentally and explains the effects of binary mixture components on relative ionization efficiencies. The proposed mechanism may also play a role in ionization by other voltage-free methods. (Figure Presented). © 2015 American Chemical Society.

Fulltext

Analytical Chemistry

Zero Volt Paper Spray Ionization and Its Mechanism

Ambient ionization is achieved by spraying from a carbon nanotube (CNT)-impregnated paper surface under the influence of small voltages (≥3 V). Organic molecules give simple high-quality mass spectra without fragmentation in the positive or negative ion modes. Conventional field ionization is ruled out, and it appears that field emission of microdroplets occurs. Microscopic examination of the CNT paper confirms that the nanoscale features at the paper surface are responsible for the high electric fields. Raman spectra imply substantial current flows in the nanotubes. The performance of this analytical method was demonstrated for a range of volatile and nonvolatile compounds and a variety of matrices. Low voltage: A carbon-nanotube-impregnated paper can be used to generate ions from organic molecules at potentials as low as 3 V. Common pesticides from the surface of an orange, ingredients of tablets, and a variety of analytes, such as amino acids, were characterized by this method. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Angewandte Chemie - International Edition

Molecular ionization from carbon nanotube paper

The difference in size, shape, and chemical cues of leaves and flowers display the underlying genetic makeup and their interactions with the environment. The need to understand the molecular signatures of these fragile plant surfaces is illustrated with a model plant, Madagascar periwinkle (Catharanthus roseus (L.) G. Don). Flat, thin layer chromatographic imprints of leaves/petals were imaged using desorption electrospray ionization mass spectrometry (DESI MS), and the results were compared with electrospray ionization mass spectrometry (ESI MS) of their extracts. Tandem mass spectrometry with DESI and ESI, in conjunction with database records, confirmed the molecular species. This protocol has been extended to other plants. Implications of this study in identifying varietal differences, toxic metabolite production, changes in metabolites during growth, pest/pathogen attack, and natural stresses are shown with illustrations. The possibility to image subtle features like eye color of petals, leaf vacuole, leaf margin, and veins is demonstrated. © 2013 American Chemical Society.

Journal of Agricultural and Food Chemistry

Understanding the molecular signatures in leaves and flowers by desorption electrospray ionization mass spectrometry (DESI MS) imaging

Tulsi or Holy Basil (Ocimum sanctum Linn) is a medicinally important plant. Ursolic acid (UA) and oleanolic acid (OA) are among its major constituents which account for many medicinal activities of the plant. In the present work, we deployed a new ambient ionization method, leaf spray ionization, for rapid detection of UA, OA and their oxidation products from tulsi leaves. Tandem electrospray ionization mass spectrometry (ESI-MS) has been performed on tulsi leaf extracts in methanol to establish the identity of the compounds. We probed changes occurring in the relative amounts of the parent compounds (UA and OA) with their oxidized products and the latter show an increasing trend upon ageing. The findings are verified by ESI-MS analysis of tulsi leaf extracts, which shows the same trend proving the reliability of the leaf spray method. © 2012 The Royal Society of Chemistry.

Analyst

Rapid identification of molecular changes in tulsi (Ocimum sanctum Linn) upon ageing using leaf spray ionization mass spectrometry

Biological Desorption Electrospray Ionization Mass Spectrometry (DESI MS) - unequivocal role of crucial ionization factors, solvent system and substrates

Journal	Data powered by TypesetTrAC - Trends in Analytical Chemistry
Publisher	Data powered by TypesetElsevier B.V.
ISSN	01659936
Open Access	No