Lithium salts of organic aromatic acids (lithium benzoate, lithium salicylate, lithium vanillate, lithium 2,5-dimethoxybenzoate, lithium 2,5-dihydroxyterephthalate, lithium α-cyano-4-hydroxycinnamate and lithium sinapate) were synthesized and tested as potential matrices for the matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry analysis of hydrocarbons and wax esters. The analytes were desorbed using nitrogen laser (337.1 nm) and ionized via the attachment of a lithium cation, yielding [M + Li](+) adducts. The sample preparation and the experimental conditions were optimized for each matrix using stearyl behenate and n-triacontane standards. The performance of the new matrices in terms of signal intensity and reproducibility, the mass range occupied by matrix ions and the laser power threshold were studied and compared with a previously recommended lithium 2,5-dihydroxybenzoate matrix (LiDHB) (Cvačka and Svatoš, Rapid Commun. Mass Spectrom. 2003, 17, 2203). Several of the new matrices performed better than LiDHB. Lithium vanillate offered a 2-3 times and 7-9 times higher signal for wax esters and hydrocarbons, respectively. Also, the signal reproducibility improved substantially, making this matrix a suitable candidate for imaging applications. In addition, the diffuse reflectance spectra and solubility of the synthesized compounds were investigated and discussed with respect to the compound's ability to serve as MALDI matrices. The applicability of selected matrices was tested on natural samples of wax esters and hydrocarbons.
- Keywords
- MALDI matrix, cuticular hydrocarbons, lipids, lithium attachment, waxes,
- MeSH
- Lithium chemistry MeSH
- Sarcophagidae chemistry MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods MeSH
- Hydrocarbons analysis chemistry MeSH
- Waxes analysis chemistry MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Lithium MeSH
- Hydrocarbons MeSH
- Waxes MeSH
The spatial distribution of neutral lipids and hydrocarbons has been imaged using MALDI-TOF mass spectrometry on intact plant and insect surfaces, namely wings and legs of the gray flesh fly (Neobellieria bullata), wings of common fruit fly (Drosophila melanogaster), leaves of thale cress (Arabidopsis thaliana), and leaves of date palm tree (Phoenix sp.). The distribution of wax esters (WEs) and saturated and unsaturated hydrocarbons (HCs) was visualized. The samples were attached on a target and multiply sprayed with lithium or sodium 2,5-dihydroxybenzoate. The deposits were homogenous, consisting of small islands (50-150 microm) of matrix crystals separated by small areas (10 microm) of uncovered cuticle. Samples of N. bullata wings were found to contain HCs and WEs distributed close to their basal parts. The distribution of sodium and potassium ions was visualized on samples prepared by sublimation of 2,5-dihydroxybenzoic acid. Pheromonal dienes were detected on D. melanogaster female wings. A homogenous distribution of saturated WEs was observed on A. thaliana and Phoenix sp. leaf samples. The optimum number of laser shots per pixel was found to be higher than for polar compounds imaging.
- MeSH
- Arabidopsis anatomy & histology chemistry MeSH
- Arecaceae anatomy & histology MeSH
- Diptera anatomy & histology chemistry MeSH
- Potassium chemistry MeSH
- Drosophila melanogaster anatomy & histology MeSH
- Photography MeSH
- Gentisates chemistry MeSH
- Insect Proteins chemistry MeSH
- Wings, Animal anatomy & histology chemistry MeSH
- Lipids analysis chemistry MeSH
- Plant Leaves chemistry MeSH
- Lithium chemistry MeSH
- Image Processing, Computer-Assisted methods MeSH
- Plant Proteins chemistry MeSH
- Sodium chemistry MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods MeSH
- Hydrocarbons chemistry MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- 2,5-dihydroxybenzoic acid MeSH Browser
- Potassium MeSH
- Gentisates MeSH
- Insect Proteins MeSH
- Lipids MeSH
- Lithium MeSH
- Plant Proteins MeSH
- Sodium MeSH
- Hydrocarbons MeSH
Li can find itself a wide range of applications since it is the lightest metal. However, Li detection by microscopy-based techniques is problematic because of the highly susceptible nature during electron beam irradiation. ToF-SIMS is a versatile technique to detect Li but the detection of light materials is also problematic due to the large ion contaminated zone and low sputtering yield. By combining ToF-SIMS with a recently launched Xe ion source FIB-SEM, which has small ion contamination and high sputtering yield features, can produce more realistic data at near surface and below the surface region especially for the detection of lightweight materials such as Li. In this study, Li detection and mapping capabilities of ToF-SIMS attached to the FIB-SEM with Ga and Xe ion sources were discussed for Al incorporated Li7 La3 Zr2 O12 solid electrolyte sample that contains Li and Al rich regions at triple junctions. In spite of smoother milling from Ga source, Xe performs more precisely in Li mapping. Low ion contaminated zone, high sputtering yield and low straggling obtained from Monte Carlo simulations are the main advantages of Xe ion sources. The Li detection efficiency for Xe is higher than Ga source discriminating the LiAlO2 phase placed at the triple junctions of grains and La2 Zr2 O7 regions placed at the outer side of LLZO neighbouring the LiAlO2 phase. LAY DESCRIPTION: Li can find itself a wide range of applications since it is the lightest metal. However, Li detection by microscopy-based techniques is problematic because of the highly susceptible nature during electron beam irradiation. ToF-SIMS is a versatile technique to detect Li but the detection of light materials is also problematic due to the large ion contaminated zone and low sputtering yield. By combining ToF-SIMS with a recently launched Xe ion source FIB-SEM, which has small ion contamination and high sputtering yield features, can produce more realistic data at near surface and below the surface region especially for the detection of lightweight materials such as Li. In this study, Li detection and mapping capabilities of ToF-SIMS attached to the FIB-SEM with Ga and Xe ion sources were discussed for Al incorporated Li7 La3 Zr2 O12 solid electrolyte sample that contains Li and Al rich regions at triple junctions. In spite of smoother milling from Ga source, Xe performs more precisely in Li mapping. Results were also supported from Monte Carlo simulations of ion-atom interactions. The Li detection resolution of xenon is much higher than gallium source discriminating the LiAlO2 phase placed at the triple junctions of grains and La2 Zr2 O7 regions placed at the outer side of LLZO neighbouring the LiAlO2 phase.
- Keywords
- FIB-SEM, Ga ion source, Li detection, ToF-SIMS, Xe ion source,
- Publication type
- Journal Article MeSH
Functional group transformations at the group 4 metallocene framework have been demonstrated, which have provided relatively straightforward access to otherwise synthetically challenging derivatives. The pendant nitrile group in Ti and Zr metallocene complexes of the type [(η(5)-C5Me5)(η(5)-C5H4CMe2CH2CN)MCl2] was converted into an intramolecularly bound ketimido moiety by alkylation, which took place not only at the nitrile, but also at the metal centre. The choice of an alkylating reagent (alkyl/aryl lithium, Grignard reagent) was crucial: e.g., 2 equiv. of MeMgBr effected the alkylation only at the metal, yielding selectively complexes [(η(5)-C5Me5)(η(5)-C5H4CMe2CH2CN)MMe2], while the use of PhMgBr, PhLi, or MeLi instead gave selectively the ketimido complexes. Organyl lithium reagents were, however, not compatible with the titanocene derivatives. The metal-bound ketimides were subsequently cleaved off by the reaction with HCl, which afforded metallocene dichlorides with a pendant imino group. These compounds were easily protonated again at the nitrogen atom to produce a cationic iminium moiety. Aqueous hydrolysis of the imine or its respective hydrochloride proved to be viable in the case of Zr and it finally afforded a pendant ketone group attached to the zirconocene framework.
- Publication type
- Journal Article MeSH
Electronically driven micromanipulation (EDM) with microscopic control was used as a novel tool for sample preparation prior to direct (matrix assisted) laser desorption/ionization mass spectrometric ((MA)LDI-MS) analysis of mature pea seed coat composition in defined layers. Microscissors were used for seed coat fragment shape adjustment, microtweezers for sample holding and "microjackhammer" Milling Pro for precise mechanical removing of cell layers in defined depths (2, 5 or 10 μm). These procedures circumvent the application of embedding media or enzymatic digestion of seed coat that would complicate mass spectra interpretation (presence of matrix signals, analyte signals enhancement or attenuation) and represent alternative for 3D metabolites profiling. In addition, microinjector was used to apply a solution on intact or micropeeled seed coat surface in nano-volumes, i.e. MALDI matrix and/or lithium salt, that provide improvement of signal of sugars. Utilization of EDM enabled optimization of matrix composition on a single small fragment of seed coat overcoming thus problems with biological (seed to seed) variability. LDI-MS data were studied by multivariate statistical analysis and significant metabolites in particular layers of seed coats were identified. Normalized intensities of signals (NS) of long-chain hydroxylated fatty acids (HLFA) on intact dormant pea genotype (JI64) seed coats were significantly higher than in their counterparts treated by micropeeling confirming HLFA accumulation in outermost layers (cutin). Fatty acids distribution differences between dormant and non-dormant genotypes were explored in detail. On the other hand, NS of sugar chains and particular polyphenols were significantly higher in micropeeled seed coats of studied dormant and non-dormant genotypes than in intact seed coats. Furthermore, combination of EDM with mass spectrometry imaging (MSI) allowed vertical profiling of metabolites in hilum (a place of former attachment of seed to maternal plant) and comparison of its composition with surrounding tissues. The obtained results contribute to the understanding of relations between seed coat chemical composition and physical seed dormancy.
- Keywords
- Cell wall, Fatty acid, Laser desorption ionization mass spectrometry, Micromanipulation, Secondary metabolite, Seed,
- MeSH
- Lasers MeSH
- Micromanipulation MeSH
- Seeds * MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods MeSH
- Plant Dormancy * MeSH
- Publication type
- Journal Article MeSH
