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1.
《Journal of mass spectrometry : JMS》2017,52(9):580-590
Scientific objectives of current and future space missions are focused on the investigation of the origin and evolution of the solar system with the particular emphasis on habitability and signatures of past and present life. For in situ measurements of the chemical composition of solid samples on planetary surfaces, the neutral atmospheric gas and the thermal plasma of planetary atmospheres, the application of mass spectrometers making use of time‐of‐flight mass analysers is a technique widely used. However, such investigations imply measurements with good statistics and, thus, a large amount of data to be analysed. Therefore, faster and especially robust automated data analysis with enhanced accuracy is required. In this contribution, an automatic data analysis software, which allows fast and precise quantitative data analysis of time‐of‐flight mass spectrometric data, is presented and discussed in detail. A crucial part of this software is a robust and fast peak finding algorithm with a consecutive numerical integration method allowing precise data analysis. We tested our analysis software with data from different time‐of‐flight mass spectrometers and different measurement campaigns thereof. The quantitative analysis of isotopes, using automatic data analysis, yields results with an accuracy of isotope ratios up to 100 ppm for a signal‐to‐noise ratio (SNR) of 104. We show that the accuracy of isotope ratios is in fact proportional to SNR−1. Furthermore, we observe that the accuracy of isotope ratios is inversely proportional to the mass resolution. Additionally, we show that the accuracy of isotope ratios is depending on the sample width T s by T s0.5. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
2.
Dr. Boris D. Zlatopolskiy Dipl.‐Chem. Philipp Krapf Dipl.‐Chem. Raphael Richarz Dr. Holm Frauendorf Prof. Dr. Felix M. Mottaghy Prof. Dr. Bernd Neumaier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4697-4703
Owing to their broad spectrum of biological activities and low toxicity, β‐lactams are attractive lead structures for the design of novel molecular probes. However, the synthesis of positron emission tomography (PET)‐isotope‐labelled β‐lactams has not yet been reported. Herein, we describe the simple preparation of radiofluorinated β‐lactams by using the fast Kinugasa reaction between 18F‐labelled nitrone [18F]‐ 1 and alkynes of different reactivity. Additionally, 18F‐labelled fused β‐lactams were obtained through the reaction of a cyclic nitrone 7 with radiofluorinated alkynes [18F]‐ 6 a , b . Radiochemical yields of the Kinugasa reaction products could be significantly increased by the use of different CuI ligands, which additionally allowed a reduction in the amount of precursor and/or reaction time. Model radiofluorinated β‐lactam‐peptide and protein conjugates ([18F]‐ 10 and 18F‐labelled BSA conjugate) were efficiently obtained in high yield under mild conditions (aq. MeCN, ambient temperature) within a short reaction time, demonstrating the suitability of the developed method for radiolabelling of sensitive molecules such as biopolymers. 相似文献
3.
Martin R. L. Paine Benjamin B. Kirk Simon Ellis‐Steinborner Stephen J. Blanksby 《Rapid communications in mass spectrometry : RCM》2009,23(18):2867-2877
2,3‐Dimethyl‐2,3‐dinitrobutane (DMNB) is an explosive taggant added to plastic explosives during manufacture making them more susceptible to vapour‐phase detection systems. In this study, the formation and detection of gas‐phase [M+H]+, [M+Li]+, [M+NH4]+ and [M+Na]+ adducts of DMNB was achieved using electrospray ionisation on a triple quadrupole mass spectrometer. The [M+H]+ ion abundance was found to have a strong dependence on ion source temperature, decreasing markedly at source temperatures above 50°C. In contrast, the [M+Na]+ ion demonstrated increasing ion abundance at source temperatures up to 105°C. The relative susceptibility of DMNB adduct ions toward dissociation was investigated by collision‐induced dissociation. Probable structures of product ions and mechanisms for unimolecular dissociation have been inferred based on fragmentation patterns from tandem mass (MS/MS) spectra of source‐formed ions of normal and isotopically labelled DMNB, and quantum chemical calculations. Both thermal and collisional activation studies suggest that the [M+Na]+ adduct ions are significantly more stable toward dissociation than their protonated analogues and, as a consequence, the former provide attractive targets for detection by contemporary rapid screening methods such as desorption electrospray ionisation mass spectrometry. Copyright © 2009 Commonwealth of Australia. Published by John Wiley & Sons, Ltd. 相似文献
4.
I. S. Molchan G. E. Thompson P. Skeldon N. Trigoulet A. Tempez P. Chapon N. Tuccitto A. Licciardello 《Surface and interface analysis : SIA》2010,42(4):211-214
The performance of glow discharge time‐of‐flight mass spectrometry in isotopic differentiation is revealed using the distribution of oxygen isotopes 16O and 18O in barrier‐type anodic alumina films as a focus. Anodic alumina films comprising 18O‐rich layers of controlled thickness were formed by the appropriate combination of anodising of superpure aluminium in electrolytes enriched with 18O isotopes and of natural abundance of 18O isotopes. Analysis of the elemental depth profiles of selected ionic species, i.e. 16O18O, allowed determination of the locations of the 18O‐rich layers and the 18O/16O interface. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
5.
The chemical synthesis of isoxanthopterin and 6‐phenylisoxanthopterin N8‐(2′‐deoxy‐β‐D ‐ribofuranosyl nucleosides) is described as well as their conversion into suitably protected 3′‐phosphoramidite building blocks to be used as marker molecules for DNA synthesis. Applying the npe/npeoc (=2‐(4‐nitrophenyl)ethyl/[2‐(4‐nitrophenyl)ethoxy]carbonyl) strategy, we used the new building blocks in the preparation of oligonucleotides by an automated solid‐support approach. The hybridization properties of a series of labelled oligomers were studied by UV‐melting techniques. It was found that the newly synthesized markers only slightly interfered with the abilities of the labelled oligomers to form stable duplexes with complementary oligonucleotides. 相似文献
6.
Martin Adiels Thomas Larsson Pauline Sutton Marja‐Riitta Taskinen Jan Borén Barbara A. Fielding 《Rapid communications in mass spectrometry : RCM》2010,24(5):586-592
Stable isotope kinetic studies play an important role in the study of very‐low density lipoprotein (VLDL) metabolism, including basic and clinical research. Today, [1,1,2,3,3‐2H5]glycerol is the most cost‐effective alternative to measure glycerol and triglyceride kinetics. Recycling of glycerol from glycolysis and gluconeogenesis may lead to incompletely labelled tracer molecules. Many existing methods for the measurement of glycerol isotopic enrichment involve the production of glycerol derivatives that result in fragmentation of the glycerol molecule after ionization. It would be favourable to measure the intact tracer molecule since incompletely labelled tracer molecules may be measured as fully labelled. The number of methods available to measure the intact tracer in biological samples is limited. The aim of this project was to develop a gas chromatography/mass spectrometry (GC/MS) method for glycerol enrichment that measures the intact glycerol backbone and is suitable for electron ionization (EI), which is widely available. A previously published method for N‐methyl‐N‐[tert‐butyldimethylsilyl]trifluoroacetamide (MTBSTFA) derivatization was significantly improved; we produced a stable derivative and increased recovery 27‐fold in standards. We used the optimized MTBSTFA method in VLDL‐triglyceride and found that further modification was required to take matrix effects into account. We now have a robust method to measure glycerol isotopic enrichment by GC/EI‐MS that can be used to rule out the known problem of tracer recycling in studies of VLDL kinetics. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
E. Anthony Evans 《Journal of Radioanalytical and Nuclear Chemistry》1981,64(1-2):9-32
Compounds labelled with radioisotopes such as14C,3H,32P,35S and125I, are essential tools for research and especially in the life sciences. Syntheses can be directed to isotopic labelling or
to non-isotopic labelling. In isotopic labelling a compound is labelled with an isotope of an element already present in the
compound whereas non-isotopic labelling is achieved with an isotope is foreign to the material or compound being labelled.
This paper reviews the properties of the more important and commonly used radioisotopes in research and methods currently
employed for the synthesis of radiolabelled compounds. The relative ease of measurement of radioactivity in large numbers
of samples, when compared for example with the measurement of mass, and the great sensitivity with which very small quantities
of radioactive compounds can be accurately measured, has resulted in the widespread need and use of radiolebelled compounds.
Methods for the practicable labelling of compounds for use as radiotracers all into three main categories, namely, chemical
systhesis, biochemical methods and isotope exchange reactions. Examples are chosen to illustrate these methods for the labelling
of amino acids, peptides, proteins, carbohydrates, lipids, neurochemicals, nucleic acids, steroids and miscellaneous compounds
of interest in biological research. Most methods of labelling employed lead to specific labelling, that is, to modecules in
which the position(s) of the radioactive atom(s) is known with certainty. However, isotope exchange reactions which are especially
useful for labelling molecules with tritium are often non-specific. The routine use of tritium nuclear magnetic resonance
spectroscopy has resolved any uncertainties in the specificity of labelling with tritium. Examples are given illustrating
the effectiveness of this valuable analytical technique. A review of the synthesis of radiolabelled compounds would not be
complete without reference to the special properties of the labelled compounds themselves which affect their useful shelf-life,
self-decomposition, purification and analysis; factors which all need to be clearly understood in order to use radiolabelled
compounds with confidence in scientific research. 相似文献
8.
Two‐dimensional (2D) layered nanomaterials, e.g. graphene and molybdenum disulfide (MoS2), have rapidly emerged in material sciences due to their unique physical, chemical and mechanical properties. In the meanwhile, there is a growing interest in constructing electrochemical sensors for a wide range of chemical and biological molecules by using these 2D nanomaterials. In this review, we summarize recent advances on using graphene and MoS2 for the development of electrochemical sensors for small molecules, proteins, nucleic acids and cells detection. We also provide our perspectives in this rapidly developing field. 相似文献
9.
Norbert Kuhn Klaus Eichele Manfred Steimann Ahmed Al‐Sheikh Bernd Doser Christian Ochsenfeld 《无机化学与普通化学杂志》2006,632(14):2268-2275
Hydrogen Bonds with Cyanide Ions? The Structures of 1,3‐Diisopropyl‐4,5‐dimethylimidazolium Cyanide and 1‐Isopropyl‐3,4,5‐trimethylimidazolium Cyanide 1,3‐Diisopropyl‐4,5‐dimethylimidazolium cyanide ( 2a ) and 1‐isopropyl‐3,4,5‐trimethylimidazolium cyanide ( 2b ) are obtained from the reaction of the corresponding 2,3‐dihydrodimethylimidazol‐2‐ylidenes ( 1 ) and hydrogen cyanide in excellent yield. Their crystal structure analyses reveal the presence of ion pairs linked by hydrogen bonds. The crystal structure analysis of 2a reveals a near colinear orientation of the C(1)‐H bond axis and the cyanide ion while in 2b this orientation is perpendicular. In both cases, the interionic distances are in the expected range for hydrogen bonds. Ab‐initio calculations of the total energy of the salts 2 indicate small differences in energy between the colinear and perpendicular orientation of the ions as well as between the colinear C‐H···C‐N and C‐H···N‐C orientations. The comparison of calculated and measured 13C and 15N NMR chemical shifts does not allow the distinction between the possible orientations. 相似文献
10.
Derek C. Macallan Daniel A. Abaye Simone Dottin Myriam Onanga Maryvonne Kombila Arnaud Dzeing‐Ella Peter G. Kremsner Sanjeev Krishna Timothy Planche 《Rapid communications in mass spectrometry : RCM》2009,23(16):2467-2475
Understanding blood volume changes in children with malaria is important for managing fluid status. Traditionally, blood/red cell volume measurements have used radioactive chromium isotopes. We applied an alternative approach, using non‐radioactive chromium‐53 labelling and mass spectrometry to investigate red cell volume (RCV) in Gabonese children with malaria. Nineteen children with malaria participated (10 severe, 9 moderately severe; ages 15 months to 7 years). Blood labelled with 53Cr‐chromate ex vivo was re‐injected, then sampled 30 min later. Pre‐ and post‐injection 53Cr content were measured by gas chromatography/electron ionisation mass spectrometry of the chromium‐trifluoroacetylacetone (TFA) chelate, calibrated against 50Cr standards. Blood and red cell volumes were calculated from isotopic dilution in 15 of 19 children (in four, insufficient signal mitigated analysis). In this small pilot study, there were no significant differences between moderate and severe cases. Including all subjects, the mean RCV was reduced compared with predicted values (184 vs. 269 mL; p = 0.016) but blood volume, 71 ± 33 mL/kg (normalised for weight), was close to predicted, ~77 mL/kg, commensurate with reduced haematocrit. Blood lactate concentration correlated negatively with RCV/weight (r = ?0.56, p = 0.028), consistent with anaemia. In one case, sequential samples over 42 days gave an estimated rate of 53Cr disappearance of 1.4%/day (equivalent half‐life: 70 days). 53Cr‐labelling of red cells may be used to estimate blood and red cell volumes and can be used as an investigative tool in situations such as childhood diseases and resource‐constrained settings. Although the red cell mass is depleted in malaria, the blood volume appears relatively well preserved. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
11.
Hisayuki Horai Masanori Arita Shigehiko Kanaya Yoshito Nihei Tasuku Ikeda Kazuhiro Suwa Yuya Ojima Kenichi Tanaka Satoshi Tanaka Ken Aoshima Yoshiya Oda Yuji Kakazu Miyako Kusano Takayuki Tohge Fumio Matsuda Yuji Sawada Masami Yokota Hirai Hiroki Nakanishi Kazutaka Ikeda Naoshige Akimoto Takashi Maoka Hiroki Takahashi Takeshi Ara Nozomu Sakurai Hideyuki Suzuki Daisuke Shibata Steffen Neumann Takashi Iida Ken Tanaka Kimito Funatsu Fumito Matsuura Tomoyoshi Soga Ryo Taguchi Kazuki Saito Takaaki Nishioka 《Journal of mass spectrometry : JMS》2010,45(7):703-714
MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron‐ionization mass spectrometry(EI‐MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)‐MSn data of 2337 authentic compounds of metabolites, 11 545 EI‐MS and 834 other‐MS data of 10 286 volatile natural and synthetic compounds, and 3045 ESI‐MS2 data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI‐MS2 data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass‐to‐charge ratio are optimized to the ESI‐MS2 data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI‐MS2 data on an identical compound under different collision‐induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21–23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
Yanhui Cui Qinghe Zhao Xiaojun Wu Xin Chen Jinlong Yang Yuetao Wang Runzhi Qin Shouxiang Ding Yongli Song Junwei Wu Kai Yang Zijian Wang Zongwei Mei Zhibo Song Hong Wu Zhongyi Jiang Guoyu Qian Luyi Yang Feng Pan 《Angewandte Chemie (International ed. in English)》2020,59(38):16594-16601
Aqueous zinc (Zn) batteries (AZBs) are widely considered as a promising candidate for next‐generation energy storage owing to their excellent safety features. However, the application of a Zn anode is hindered by severe dendrite formation and side reactions. Herein, an interfacial bridged organic–inorganic hybrid protection layer (Nafion‐Zn‐X) is developed by complexing inorganic Zn‐X zeolite nanoparticles with Nafion, which shifts ion transport from channel transport in Nafion to a hopping mechanism in the organic–inorganic interface. This unique organic–inorganic structure is found to effectively suppress dendrite growth and side reactions of the Zn anode. Consequently, the Zn@Nafion‐Zn‐X composite anode delivers high coulombic efficiency (ca. 97 %), deep Zn plating/stripping (10 mAh cm?2), and long cycle life (over 10 000 cycles). By tackling the intrinsic chemical/electrochemical issues, the proposed strategy provides a versatile remedy for the limited cycle life of the Zn anode. 相似文献
13.
Markus Holzweber Ernst Pittenauer Herbert Hutter 《Journal of mass spectrometry : JMS》2010,45(10):1104-1110
A systematic study of five different imidazolium‐based room temperature ionic liquids, 1‐butyl‐3‐methylimidazolium acetate, 1‐butyl‐3‐methylimidazolium nitrate, 1‐butyl‐3‐methylimidazolium iodide, 1‐butyl‐3‐methylimidazolium hexafluorophosphate and 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide were carried out by means of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) in positive and negative ion mode. The compounds were measured under Bi‐ion and Bi‐cluster ions (Bi2–7+, Bi3, 52+) bombardment, and spectral information and general rules for the fragmentation pattern are presented. Evidence for hydrogen bonding, due to high molecular secondary cluster ions, could be found. Hydrogen bonding strength could be estimated by ToF‐SIMS via correlation of the anionic yield enhancement with solvent parameters. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
Anupam Giri Marion Coutriade Amandine Racaud Pierre‐Hugues Stefanuto Koji Okuda John Dane Robert B. Cody Jean‐Franois Focant 《Journal of mass spectrometry : JMS》2019,54(2):148-157
Comprehensive two‐dimensional gas chromatography (GC × GC) coupled to time‐of‐flight mass spectrometry is a powerful separation tool for complex petroleum product analysis. However, the most commonly used electron ionization (EI) technique often makes the identification of the majority of hydrocarbons impossible due to the exhaustive fragmentation and lack of molecular ion preservation, prompting the need of soft‐ionization energies. In this study, three different soft‐ionization techniques including photo ionization (PI), chemical ionization (CI), and field ionization (FI) were compared against EI to elucidate their relative capabilities to reveal different base oil hydrocarbon classes. Compared with EI (70 eV), PI (10.8 eV) retained significant molecular ion (M+·) information for a large number of isomeric species including branched‐alkanes and saturated monocyclic hydrocarbons along with unique fragmentation patterns. However, for bicyclic/polycyclic naphthenic and aromatic compounds, EI played upper hand by retaining molecular as well as fragment ions to identify the species, whereas PI exhibited mainly molecular ion signals. On the other hand, CI revealed selectivity towards different base oil groups, particularly for steranes, sulfur‐containing thiophenes, and esters, yielding protonated molecular ions (M + H)+ for unsaturated and hydride abstracted ions (M‐H+) for saturated hydrocarbons. FI, as expected, generated intact molecular ions (M+·) irrespective to the base oil chemical classes. It allowed elemental composition by TOFMS with a mass resolving power up to 8000 (FWHM) and a mass accuracy of 1 mDa, leading to the calculation of heteroatomic content, double bond equivalency, and carbon number of the compounds. The qualitative and quantitative results presented herein offer a unique perspective into the detailed comparison of different ionization techniques corresponding to several hydrocarbon classes. 相似文献
15.
This report is a summary of our work on energetic materials. Herein, triazole‐, tetrazole‐, 2‐tetrazene‐ and hydrazine‐based energetic compounds are described. An overview of the synthetic methods and of the problematic around the quest of new explosives is given. Hydrogen‐bonding formation and alkylation (methylation) reactions were studied as a mean to decrease the sensitivities towards classical stimuli and increase their thermal and chemical stability. 15N NMR spectroscopy is a valuable tool for the assignment of the methylation site in keeping with the results of the crystal structure analysis. Lastly, the thermal/chemical stability, sensitivity data and energetic performance of the compounds is described. 相似文献
16.
H. Schierbeek R. Rieken K. Y. Dorst C. Penning J. B. van Goudoever 《Rapid communications in mass spectrometry : RCM》2009,23(22):3549-3554
The doubly labelled water method is valuable for measuring energy expenditure in humans. It usually involves blood or urine sampling, which might be difficult in neonates and children with cerebral palsy or other disabilities. We therefore aimed to validate a method making use of saliva samples analyzed by automated thermal conversion elemental analyzer in combination with isotope ratio mass spectrometry (TC‐EA/IRMS). The subjects received labelled water orally and urine and saliva samples were collected and analyzed. Deuterium as well as oxygen18 was measured in one single run using a peak jump method. Excellent linearity was found for measurement of enrichments of deuterium (R2 = 0.9999) and oxygen18 (R2 = 0.9999). The intra‐assay precision and the inter‐assay precision of the measurement of two standards were good for both deuterium and oxygen18. The variation between urine and saliva samples was small (4.83% for deuterium and 2.33% for oxygen18 n = 40). Saliva sampling is to be preferred, therefore, as it can be easily collected and is non‐invasive. Moreover, its time of production is almost exactly known. The TC‐EA/IRMS method is a good alternative to the more laborious off‐line IRMS measurements. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
Thomas Schmid Lothar Opilik Carolin Blum Renato Zenobi 《Angewandte Chemie (International ed. in English)》2013,52(23):5940-5954
Methods for chemical analysis at the nanometer scale are crucial for understanding and characterizing nanostructures of modern materials and biological systems. Tip‐enhanced Raman spectroscopy (TERS) combines the chemical information provided by Raman spectroscopy with the signal enhancement known from surface‐enhanced Raman scattering (SERS) and the high spatial resolution of atomic force microscopy (AFM) or scanning tunneling microscopy (STM). A metallic or metallized tip is illuminated by a focused laser beam and the resulting strongly enhanced electromagnetic field at the tip apex acts as a highly confined light source for Raman spectroscopic measurements. This Review focuses on the prerequisites for the efficient coupling of light to the tip as well as the shortcomings and pitfalls that have to be considered for TERS imaging, a fascinating but still challenging way to look at the nanoworld. Finally, examples from recent publications have been selected to demonstrate the potential of this technique for chemical imaging with a spatial resolution of approximately 10 nm and sensitivity down to the single‐molecule level for applications ranging from materials sciences to life sciences. 相似文献
18.
Patrice Tremblay Martine M Savard Anna Smirnoff Real Paquin 《Rapid communications in mass spectrometry : RCM》2009,23(14):2213-2220
Gaseous membrane permeation (MP) technologies have been combined with continuous‐flow isotope ratio mass spectrometry for on‐line δ13C measurements. The experimental setup of membrane permeation‐gas chromatography/combustion/isotope ratio mass spectrometry (MP‐GC/C/IRMS) quantitatively traps gas streams in membrane permeation experiments under steady‐state conditions and performs on‐line gas transfer into a GC/C/IRMS system. A commercial polydimethylsiloxane (PDMS) membrane sheet was used for the experiments. Laboratory tests using CO2 demonstrate that the whole process does not fractionate the C isotopes of CO2. Moreover, the δ13C values of CO2 permeated on‐line give the same isotopic results as off‐line static dual‐inlet IRMS δ13C measurements. Formaldehyde generated from aqueous formaldehyde solutions has also been used as the feed gas for permeation experiments and on‐line δ13C determination. The feed‐formaldehyde δ13C value was pre‐determined by sampling the headspace of the thermostated aqueous formaldehyde solution. Comparison of the results obtained by headspace with those from direct aqueous formaldehyde injection confirms that the headspace sampling does not generate isotopic fractionation, but the permeated formaldehyde analyzed on‐line yields a 13C enrichment relative to the feed δ13C value, the isotopic fractionation being 1.0026 ± 0.0003. The δ13C values have been normalized using an adapted two‐point isotopic calibration for δ13C values ranging from ?42 to ?10‰. The MP‐GC/C/IRMS system allows the δ13C determination of formaldehyde without chemical derivatization or additional analytical imprecision. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
19.
Chemoselective detection and discrimination of carbonyl‐containing compounds in metabolite mixtures by 1H‐detected 15N nuclear magnetic resonance
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Andrew N. Lane Sengodagounder Arumugam Pawel K. Lorkiewicz Richard M. Higashi Sébastien Laulhé Michael H. Nantz Hunter N.B. Moseley Teresa W.‐M. Fan 《Magnetic resonance in chemistry : MRC》2015,53(5):337-343
NMR spectra of mixtures of metabolites extracted from cells or tissues are extremely complex, reflecting the large number of compounds that are present over a wide range of concentrations. Although multidimensional NMR can greatly improve resolution as well as improve reliability of compound assignments, lower abundance metabolites often remain hidden. We have developed a carbonyl‐selective aminooxy probe that specifically reacts with free keto and aldehyde functions, but not carboxylates. By incorporating 15N in the aminooxy functional group, 15N‐edited NMR was used to select exclusively those metabolites that contain a free carbonyl function while all other metabolites are rejected. Here, we demonstrate that the chemical shifts of the aminooxy adducts of ketones and aldehydes are very different, which can be used to discriminate between aldoses and ketoses, for example. Utilizing the 2‐bond or 3‐bond 15N‐1H couplings, the 15N‐edited NMR analysis was optimized first with authentic standards and then applied to an extract of the lung adenocarcinoma cell line A549. More than 30 carbonyl‐containing compounds at NMR‐detectable levels, six of which we have assigned by reference to our database. As the aminooxy probe contains a permanently charged quaternary ammonium group, the adducts are also optimized for detection by mass spectrometry. Thus, this sample preparation technique provides a better link between the two structural determination tools, thereby paving the way to faster and more reliable identification of both known and unknown metabolites directly in crude biological extracts. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
Mika Tiainen Hannu Maaheimo Pasi Soininen Reino Laatikainen 《Magnetic resonance in chemistry : MRC》2010,48(2):117-122
The one‐ and two‐bond 13C isotope shifts, typically ?1.5 to ?2.5 ppb and ?0.7 ppb respectively, in non‐cyclic aliphatic systems and up to ?4.4 ppb and ?1.0 ppb in glucose cause effects that need to be taken into account in the adaptive NMR spectral library‐based quantification of the isotopomer mixtures. In this work, NMR spectral analyses of some 13C‐labelled amino acids, D ‐glucose and other small compounds were performed in order to obtain rules for prediction of the 13C isotope effects on 1H chemical shifts. It is proposed that using the additivity rules, the isotope effects can be predicted with a sufficient accuracy for amino acid isotopomer applications. For glucose the effects were found strongly non‐additive. The complete spectral analysis of fully 13C‐labelled D ‐glucose made it also possible to assign the exocyclic proton signals of the glucose. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献