In Vivo Nanoelectrospray for the Localization of Bioactive Molecules in Plants by Mass Spectrometry

The method for the localization of bioactive molecules in plants is highly needed since it provides a fundamental prerequisite for understanding their physiological and ecological functions. Here, we propose a simple method termed in vivo nanoelectrospray for the localization of bioactive molecules in plants without sample preparation. A capillary is partly inserted into the plant to sample liquid from a highly located region, and then, a high voltage is applied to the plant to generate an electrospray from the capillary tip for mass spectrometry analysis. Using this method, bioactive molecules such as saccharides, glycoalkaloids, flavonoids, organic acids, and glucosinolates (GLs) are detected in the target regions of living plants or fresh fruits. Original information for endogenous chemicals including liable molecules in plant can be obtained. A sketchy three-dimensional distribution of glycoalkaloids in a cherry tomato has been obtained. The present work provides a powerful tool for the study of bioactive molecules in a living plant by mass spectrometry

Controlling Charge States of Peptides through Inductive Electrospray Ionization Mass Spectrometry

A novel ionization device for controlling the charge states of peptides based on an inductive elecrospray ionization technique was developed. This ion source keeps the major capabilities of electrospray ionization (ESI) which is compatible with liquid separation techniques (such as liquid chromatography (LC) and capillary electrophoresis (CE)) and can be potentially used to control the charge states of peptides accurately by simply varying the AC voltage applied. In comparison with conventional ESI, inductive ESI successfully simplifies the mass spectrum by reducing the charge states of peptide to a singly charged one, as well as eliminating the adduct ions

Rapid Analysis of Unsaturated Fatty Acids on Paper-Based Analytical Devices via Online Epoxidation and Ambient Mass Spectrometry

In this work, we demonstrate a novel design that allows rapid online identification and quantitation of unsaturated fatty acid CC location isomers via epoxidation and ambient mass spectrometry (MS). Unsaturated fatty acid solution was loaded on a paper strip placed between a low-temperature plasma probe and the inlet of a mass spectrometer. Reactive oxygen species in the plasma promoted epoxidation at the CC, and the product was simultaneously ionized. Upon collision-induced dissociation (CID), the epoxidation product was fragmented to release diagnostic ions specific to the CC location. The whole analytical workflow can be completed within 5 s and is particularly promising for point-of-care (POC) clinical diagnosis, considering its fast, high-throughput nature, and coupling with paper-based analytical devices

Monitoring Effect of SO₂ Emission Abatement on Recovery of Acidified Soil and Streamwater in Southwest China

Following Europe and North America, East Asia has become a global hotspot of acid deposition, with very high deposition of both sulfur (S) and nitrogen (N) occurring in large areas in southwest and southeast China. Great efforts have been made in reducing national emission of sulfur dioxide (SO₂) since 2006 in China. However, the total emission of nitrogen oxides (NOx) continued to increase until 2011. To evaluate the effects of SO₂ and NOx emission abatement on acid deposition and acidification of soil and water, we monitored the chemical composition of throughfall, soil water, and streamwater from 2001 to 2013 in a small, forested catchment near Chongqing city in Southwestern China. The deposition of S decreased significantly, whereas N deposition increased in the recent years. This clearly showed the effect of SO₂ abatement but not of NOx. Overall the rate of acid deposition was reduced. However, there was delay in the recovery of soil and surface water from acidification, probably due to desorption of previously stored sulfate (SO₄^2–) and increase in nitrate (NO₃^–) leaching from soil. The average acid input by N transformations has greatly exceeded the H⁺ input directly by atmospheric deposition. The reversal of acidification with an increase in pH of soil water, requires additional abatement of emissions of both SO₂ and NOx

MS³ Imaging Enables the Simultaneous Analysis of Phospholipid CC and <i>sn</i>-Position Isomers in Tissues

Mass spectrometry (MS) imaging of lipids in tissues with high structure specificity is challenging in the effective fragmentation of position-selective structures and the sensitive detection of multiple lipid isomers. Herein, we develop an MS3 imaging method for the simultaneous analysis of phospholipid CC and sn-position isomers by on-tissue photochemical derivatization, nanospray desorption electrospray ionization (nano-DESI), and a dual-linear ion trap MS system. A novel laser-based sensing probe is developed for the real-time adjustment of the probe-to-surface distance for nano-DESI. This method is validated in mouse brain and kidney sections, showing its capability of sensitive resolving and imaging of the fatty acyl chain composition, the sn-position, and the CC location of phospholipids in an MS3 scan. MS3 imaging of phospholipids has shown the capability of differentiation of cancerous, fibrosis, and adjacent normal regions in liver cancer tissues

Photochemical Tagging for Quantitation of Unsaturated Fatty Acids by Mass Spectrometry

Fatty acid (FA) profiling provides phenotypic information and is increasingly used in a broad range of biological and biomedical studies. Quantitation of unsaturated FAs with confident carbon–carbon double bond (CC) location assignment is both sample and time consuming using traditional gas chromatography mass spectrometry analysis. In this study, we developed a rapid, sensitive, and quantitative method for profiling unsaturated FAs without using chromatographic separations. This method was based on a combination of in-solution photochemical tagging of a CC in FAs and a subsequent gas-phase detagging via tandem (neutral loss scan) mass spectrometry. It enabled quantitation of unsaturated FAs from various biological samples (blood, plasma, and cell lines). More importantly, quantitative information on FA CC location isomers, which was traditionally overlooked, could now be obtained and applied to studying FA changes between normal and cancerous human prostate cells

Paleoenvironment and Organic Characterization of the Lower Cretaceous Lacustrine Source Rocks in the Erlian Basin: The Influence of Hydrothermal and Volcanic Activity on the Source Rock Quality

Lower Cretaceous lacustrine source rocks in the Erlian Basin are highly heterogeneous. It is important to assess and explain these heterogeneities for the reconstruction of paleoenvironments and the prediction of high-quality source rock distributions. In this study, well-logging, organic, and elemental geochemical data were comprehensively analyzed for the source rocks of Member 4 of the Aershan Formation (Fm) and Member 1 of the Tengger Fm in the southern Bayindulan (BNAN), southern Wulanhua (WLHs), Anan, Aer, and southern Wuliyasitai sags of the Erlian Basin. The variability in sedimentary environments, sources of organic matter of the source rocks in different sags, and the influence of hydrothermal and volcanic activity on the source rock quality in the Erlian Basin were assessed. The results reveal that the source rocks can be divided into four types of organic facies (A, B, BC, and C). Organic facies A–B present hydrogen indices (HIs) higher than 400 mg/g and are mainly composed of mudstone and thick (average thickness >50 m) dolomitic mudstone, with biomarkers characterized by a Pr/Ph ratio lower than 1.0, a gammacerane/C30 hopane (Gam/C30H) ratio higher than 0.2, and a C19 tricyclic terpane/C23 tricyclic terpane (C19/C23TT) ratio lower than 0.6. Organic facies BC–C are composed of mudstone with an HI < 400 mg/g, with biomarkers characterized by a Pr/Ph ratio higher than 0.8, a Gam/C30H ratio lower than 0.2, a C19/C23TT ratio higher than 0.6, and a sterane/hopane ratio lower than 0.4. Dolomitic mudstone belonging to organic facies A–B is mainly developed in the BNAN, WLHs, and Anan sag and is characterized by a fault-controlled distribution in the sag, a right-declined rare earth element pattern, and an enrichment in the elements of Ba, Cu, Zn, Fe, and Ni. The genesis of high HI dolomitic mudstone is associated with hydrothermal and volcanic activity because the hydrothermal fluid or hydrolysis of volcanic ash result in increasing input of reducing gas and soluble nutrient ions, thus promoting the formation of anoxic and saline Cretaceous lakes with high primary productivity

Development of a Miniature Mass Spectrometry System for Point-of-Care Analysis of Lipid Isomers Based on Ozone-Induced Dissociation

Disorder of lipid homeostasis is closely associated with a variety of diseases. Although mass spectrometry (MS) approaches have been well developed for the characterization of lipids, it still lacks an integrated and compact MS system that is capable of rapid and detailed lipid structural characterization and can be conveniently transferred into different laboratories. In this work, we describe a novel miniature MS system with the capability of both ozone-induced dissociation (OzID) and collision-induced dissociation (CID) for the assignment of sites of unsaturation and sn-positions in glycerolipids. A miniature ozone generator was developed, which can be operated at a relatively high pressure. By maintaining high-concentration ozone inside the linear ion trap, OzID efficiency was significantly improved for the identification of CC locations in unsaturated lipids, with reaction times as short as 10 ms. Finally, the miniature OzID MS system was applied to the analysis of CC locations and sn-positions of lipids from biological samples. Direct sampling and fast detection of changes in phospholipid isomers were demonstrated for the rapid discrimination of breast cancer tissue samples, showing the potential of the miniature OzID MS system for point-of-care analysis of lipid isomer biomarkers in complex samples

<i>In Situ</i> Ion-Transmission Mass Spectrometry for Paper-Based Analytical Devices

Current detection methods for paper-based analytical devices (PADs) rely on spectroscopic and electrochemical properties, which place special requirements on the analyte or need analyte labeling. Here, ion-transmission mass spectrometry (MS) was proposed for coupling with PADs to enable rapid <i>in situ</i> MS analysis of the sample on paper. The sample was analyzed directly on paper via analyte ionization by ions transmitted through the paper, generated by a low-temperature plasma probe. Prior to MS analysis, the sample can be separated by paper electrophoresis or by paper chromatography, among a variety of other features offered by PADs. The versatility of this technique was demonstrated by MS analysis of a paper microarray, a mixture of amino acids, and whole blood doped with drugs on PADs

Identification and Quantitation of CC Location Isomers of Unsaturated Fatty Acids by Epoxidation Reaction and Tandem Mass Spectrometry

Unsaturated fatty acids (FAs) serve as nutrients, energy sources, and signaling molecules for organisms, which are the major components for a large variety of lipids. However, structural characterization and quantitation of unsaturated FAs by mass spectrometry remain an analytical challenge. Here, we report the coupling of epoxidation reaction of the CC in unsaturated FAs and tandem mass spectrometry (MS) for rapid and accurate identification and quantitation of CC isomers of FAs in a shotgun lipidomics approach. Epoxidation of the CC leads to the production of an epoxide which, upon collision induced dissociation (CID), produces abundant diagnostic ions indicative of the CC location. The total intensity of the same set of diagnostic ions for one specific FA CC isomer was also used for its relative and absolute quantitation. The simple experimental setup, rapid reaction kinetics (<2 min), high reaction yield (>90% for monounsaturated FAs), and easy-to-interpret tandem MS spectra enable a promising methodology particularly for the analysis of unsaturated FAs in complex biological samples such as human plasma and animal tissues