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1.
Jungmann JH MacAleese L Buijs R Giskes F de Snaijer A Visser J Visschers J Vrakking MJ Heeren RM 《Journal of the American Society for Mass Spectrometry》2010,21(12):2023-2030
In mass spectrometry imaging, spatial resolution is pushed to its limits with the use of ion microscope mass spectrometric
imaging systems. An ion microscope magnifies and then projects the original spatial distribution of ions from a sample surface
onto a position-sensitive detector, while retaining time-of-flight mass separation capabilities. Here, a new type of position-sensitive
detector based on a chevron microchannel plate stack in combination with a 512 × 512 complementary metal-oxide-semiconductor
based pixel detector is coupled to an ion microscope. Spatial resolving power better than 6 μm is demonstrated by secondary
ion mass spectrometry and 8–10μm spatial resolving power is achieved with laser desorption ionization. A detailed evaluation
of key performance criteria such as spatial resolution, acquisition speed, and data handling is presented. 相似文献
2.
Critical assessment of ionization patterns and applications of ambient desorption/ionization mass spectrometry using FAPA–MS 下载免费PDF全文
Ambient desorption/ionization mass spectrometry (MS) has gained growing interest during the last decade due to its high analytical performance and yet simplicity. Here, one of the recently developed ambient desorption/ionization MS sources, the flowing atmospheric‐pressure afterglow (FAPA) source, was investigated in detail regarding background ions and typical ionization patterns in the positive as well as the negative ion mode for a variety of compound classes, comprising alkanes, alcohols, aldehydes, ketones, carboxylic acids, organic peroxides and alkaloids. A broad range of signals for adducts and losses was found, besides the usually emphasized detection of quasimolecular ions, i.e. [M + H]+ and [M ? H]? in the positive and the negative mode, respectively. It was found that FAPA–MS is best suited for polar analytes containing nitrogen and/or oxygen functionalities, e.g. carboxylic acids, with low molecular weights and relatively high vapor pressures. In addition, the source was used in proof‐of‐principle studies, illustrating the capabilities and limitations of the technique: Firstly, traces of cocaine were detected and unambiguously identified on euro banknotes using FAPA ionization in combination with tandem MS, suggesting a correlation between cocaine abundance and age of the banknote. Secondly, FAPA–MS was used for the identification of acidic marker compounds in organic aerosol samples, indicating yet‐undiscovered matrix and sample surface effects of ionization pathways in the afterglow region. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
3.
The ASMS conference on ion spectroscopy brought together at Asilomar on October 16–20, 2009 a large group of mass spectrometrists
working in the area of ion spectroscopy. In this introduction to the field, we provide a brief history, its current state,
and where it is going. Ion spectroscopy of intermediate size molecules began with photoelectron spectroscopy in the 1960s,
while electronic spectroscopy of ions using the photodissociation “action spectroscopic” mode became active in the next decade.
These approaches remained for many years the main source of information about ionization energies, electronic states, and
electronic transitions of ions. In recent years, high-resolution laser techniques coupled with pulsed field ionization and
sample cooling in molecular beams have provided high precision ionization energies and vibrational frequencies of small to
intermediate sized molecules, including a number of radicals. More recently, optical parametric oscillator (OPO) IR lasers
and free electron lasers have been developed and employed to record the IR spectra of molecular ions in either molecular beams
or ion traps. These results, in combination with theoretical ab initio molecular orbital (MO) methods, are providing unprecedented
structural and energetic information about gas-phase ions. 相似文献
4.
Graham AW Ray SJ Enke CG Barinaga CJ Koppenaal DW Hieftje GM 《Journal of the American Society for Mass Spectrometry》2011,22(1):110-117
A new instrumental concept, distance-of-flight mass spectrometry (DOFMS), is demonstrated experimentally. In DOFMS the mass-to-charge
ratio of ions is determined by the distance each ion travels during a fixed time period; the mass spectrum is then recorded
with a position-sensitive detector. The DOF approach provides a new way to separate and quantify components of complex samples.
Initial results are demonstrated with a glow discharge ion source and a microchannel plate–phosphor screen detector assembly
for atomic ion determination. This detection system demonstrated mass spectral peak widths of approximately 0.65 mm, corresponding
to resolving powers of approximately 400–600 for a number of elemental samples. 相似文献
5.
Shelley JT Chan GC Hieftje GM 《Journal of the American Society for Mass Spectrometry》2012,23(2):407-417
The advent of ambient desorption/ionization mass spectrometry (ADI-MS) has led to the development of a large number of atmospheric-pressure
ionization sources. The largest group of such sources is based on electrical discharges; yet, the desorption and ionization
processes that they employ remain largely uncharacterized. Here, the atmospheric-pressure glow discharge (APGD) and afterglow
of a helium flowing atmospheric-pressure afterglow (FAPA) ionization source were examined by optical emission spectroscopy.
Spatial emission profiles of species created in the APGD and afterglow were recorded under a variety of operating conditions,
including discharge current, electrode polarity, and plasma-gas flow rate. From these studies, it was found that an appreciable
amount of atmospheric H2O vapor, N2, and O2 diffuses through the hole in the plate electrode into the discharge to become a major source of reagent ions in ADI-MS analyses.
Spatially resolved plasma parameters, such as OH rotational temperature (Trot) and electron number density (ne), were also measured in the APGD. Maximum values for Trot and ne were found to be ~1100 K and ~4 × 1019 m–3, respectively, and were both located at the pin cathode. In the afterglow, rotational temperatures from OH and N2+ yielded drastically different values, with OH temperatures matching those obtained from infrared thermography measurements.
The higher N2+ temperature is believed to be caused by charge-transfer ionization of N2 by He2+. These findings are discussed in the context of previously reported ADI-MS analyses with the FAPA source. 相似文献
6.
V. S. Shmakov I. I. Furley A. Sh. Sultanov V. A. Dokichev R. M. Sultanova 《Russian Chemical Bulletin》2000,49(4):705-708
The negative ion mass spectra and photoelectron spectra of substituted pyrazolines were studied. A correlation between the
ionization energy of the highest occupied molecular orbital and the yield of [MeNHNH2
−] ions was found. Isomerization of molecular negative ions was studied by resonance electron capture mass spectrometry.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 701–704, April, 2000. 相似文献
7.
Barnes JH Schilling GD Hieftje GM Sperline RP Denton MB Barinaga CJ Koppenaal DW 《Journal of the American Society for Mass Spectrometry》2004,15(6):769-776
The use of laser ablation (LA) as a sample-introduction method for inductively coupled plasma mass spectrometry (ICP-MS) creates a powerful tool for trace elemental analysis. With this type of instrument, high analyte spatial resolution is possible in three dimensions with ng/g limits of detection and minimal sample consumption. Here, simultaneous detection is used to eliminate the correlated noise that plagues the ablation process. This benefit allows analyses to be performed with single laser pulses, resulting in improved depth resolution, even less sample consumption, and improved measurement precision. The new instrument includes an LA sample-introduction system coupled to an ICP ionization source and a Mattauch-Herzog mass spectrograph (MHMS) fitted with a novel array detector. With this instrument, absolute limits of detection are in the tens to hundreds of fg regime and isotope-ratio precision is better than 0.02% RSD with a one-hour integration period. Finally, depth-profile analysis has been performed with a depth resolution of 5 nm per ablation event. 相似文献
8.
Gao J Owen BC Borton DJ Jin Z Kenttämaa HI 《Journal of the American Society for Mass Spectrometry》2012,23(5):816-822
Saturated and unsaturated, linear, branched, and cyclic hydrocarbons, as well as polyaromatic and heteroaromatic hydrocarbons,
were successfully ionized by atmospheric pressure chemical ionization (APCI) using small hydrocarbons as reagents in a linear
quadrupole ion trap (LQIT) mass spectrometer. Pentane was proved to be the best reagent among the hydrocarbon reagents studied.
This ionization method generated different types of abundant ions (i.e., [M + H]+, M+•, [M – H]+ and [M – 2H]+ •), with little or no fragmentation. The radical cations can be differentiated from the even-electron ions by using dimethyl
disulfide, thus facilitating molecular weight (MW) determination. While some steroids and lignin monomer model compounds,
such as androsterone and 4-hydroxy-3-methoxybenzaldehyde, also formed abundant M+• and [M + H]+ ions, this was not true for all of them. Analysis of two known mixtures as well as a base oil sample demonstrated that each
component of the known mixtures could be observed and that a correct MW distribution was obtained for the base oil. The feasibility
of using this ionization method on the chromatographic time scale was demonstrated by using high-performance liquid chromatography
(HPLC) with hexane as the mobile phase (and APCI reagent) to separate an artificial mixture prior to mass spectrometric analysis. 相似文献
9.
Jaime Orejas Kevin P. Pfeuffer Steven J. Ray Jorge Pisonero Alfredo Sanz-Medel Gary M. Hieftje 《Analytical and bioanalytical chemistry》2014,406(29):7511-7521
Ambient desorption/ionization (ADI) sources coupled to mass spectrometry (MS) offer outstanding analytical features: direct analysis of real samples without sample pretreatment, combined with the selectivity and sensitivity of MS. Since ADI sources typically work in the open atmosphere, ambient conditions can affect the desorption and ionization processes. Here, the effects of internal source parameters and ambient humidity on the ionization processes of the flowing atmospheric pressure afterglow (FAPA) source are investigated. The interaction of reagent ions with a range of analytes is studied in terms of sensitivity and based upon the processes that occur in the ionization reactions. The results show that internal parameters which lead to higher gas temperatures afforded higher sensitivities, although fragmentation is also affected. In the case of humidity, only extremely dry conditions led to higher sensitivities, while fragmentation remained unaffected. 相似文献
10.
Venzie JL Castro J Balarama Krishna MV Nelson DM Marcus RK 《Analytical and bioanalytical chemistry》2007,389(1):321-333
A liquid chromatography–particle-beam mass spectrometer (LC–PB/MS) with interchangeable electron-impact (EI) and glow-discharge
(GD) ion sources was evaluated for future application in analysis of botanical extracts. In this work a green tea tincture
was characterized for a series of catechin components (catechin, epicatechin, epigallocatechin, and epigallocatechin gallate
(EGCG)) and caffeine. Special emphasis was given to EGCG and caffeine, because they are important in determining the possible
health effects of the green tea. The effects of instrument operating conditions were evaluated for the EI and GD ionization
sources to determine their effect on analyte intensities and fragmentation patterns. These studies furnished information about
the effects of these conditions in determining possible ionization pathways in the two ion sources. The mass spectra of these
compounds obtained with the GD ion source are EI-like in appearance, with clearly identified molecular ions and fragmentation
patterns that are easily rationalized. The absolute limits of detection for EGCG and caffeine were, respectively, 11 ng and
0.77 ng for the EI source and 3.2 ng and 0.61 ng for the GD source. The PB/EIMS and PB/GDMS combinations can be operated in
a flow-injection mode, wherein the analyte is injected directly into the mobile phase, or coupled to high-performance liquid
chromatography (HPLC), enabling LC–MS analysis of complex mixtures. A reversed-phase chromatographic separation of the green
tea tincture was performed on a commercial C18 column using a gradient of water (containing 0.1% TFA) and ACN. Quantification of EGCG and caffeine was performed by the
standard addition method. The amounts of EGCG and caffeine in the tested green tea tincture were each ∼14 mg mL−1. 相似文献
11.
Sekimoto K Sakai M Takayama M 《Journal of the American Society for Mass Spectrometry》2012,23(6):1109-1119
The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric
pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O2–, HCO3–, COO–(COOH), NO2–, NO3–, and NO3–(HNO3) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The
individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric
ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is
most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric
ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric
ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion. 相似文献
12.
A novel method using liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry in the
negative selected ion monitoring mode has been developed and validated for rapid simultaneous determination of triptolide
and tripdiolide in the extract of Tripterygium wilfordii Hook. f. The molecular ions m/z [M–H]− 359 and 375 were selected for the quantification in selected ion monitoring mode for triptolide and tripdiolide. Standard
calibration curve was linear over the concentration range of 0.12–24 and 0.15–30 μg mL−1 for triptolide and tripdiolide. The relative standard deviations of intra- and inter-day were in the range of 4.7–9.9 and
8.9–12.6%. The average recoveries were between 96.4 and 104.6%. The limits of quantitation were 2.0 × 10−3 and 2.5 × 10−3 μg mL−1 for triptolide and tripdiolide. 相似文献
13.
Leila Hejazi Diako Ebrahimi D. Brynn Hibbert Michael Guilhaus 《Rapid communications in mass spectrometry : RCM》2009,23(14):2181-2189
Orthogonal acceleration time‐of‐flight (oa‐TOF) mass spectrometry (MS) was coupled to gas chromatography (GC) to measure ion yields (ratio of ion counts to number of neutrals entering the ion source) and signal‐to‐noise (S/N) in the electron ionization (EI) mode (hard ionization) as well as in the soft ionization modes of chemical ionization (CI), electron capture negative ion chemical ionization (NICI) and field ionization (FI). Mass accuracies of the EI and FI modes were also investigated. Sixteen structurally diverse volatile organic compounds were chosen for this study. The oa‐TOF mass analyzer is highly suited for FI MS and provided an opportunity to compare the sensitivity of this ionization method to the more conventional ionization methods. Compared to the widely used quadrupole mass filter, the oa‐TOF platform offers significantly greater mass accuracy and therefore the possibility of determining the empirical formula of analytes. The findings of this study showed that, for the instrument used, EI generated the most ions with the exception of compounds able to form negative ions readily. Lower ion yields in the FI mode were generally observed but the chromatograms displayed greater S/N and in many cases gave spectra dominated by a molecular ion. Ion counts in CI are limited by the very small apertures required to maintain sufficiently high pressures in the ionization chamber. Mass accuracy for molecular and fragment ions was attainable at close to manufacturer's specifications, thus providing useful information on molecular ions and neutral losses. The data presented also suggests a potentially useful instrumental combination would result if EI and FI spectra could be collected simultaneously or in alternate scans during GC/MS. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
14.
Alberici LC Oliveira HC Catharino RR Vercesi AE Eberlin MN Alberici RM 《Analytical and bioanalytical chemistry》2011,401(5):1655-1663
Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) was used to interrogate the hepatic lipid profiles of hypertriglyceridemic
and control normotriglyceridemic mice. The analyses of ex vivo complex lipid mixtures were made directly with EASI-MS without
accompanying separation steps. Intense ions for phosphatidylcholines and triacylglycerols were observed in the positive ion
mode whereas the spectra in the negative ion mode provided profiles of phosphatidylethanolamines and phosphatidylinositol.
EASI-MS was coupled to high-performance thin-layer chromatography for analysis of free fatty acids. Fourier transform–ion
cyclotron resonance–mass spectrometry was also employed to confirm the identity of the detected lipids. We demonstrated higher
incorporation of oleic acid in phosphatidylcholine and triacylglycerol composition, higher relative abundance of arachidonic
acid containing phosphatidylinositol, and overall distinct free fatty acid profile in the livers of genetic hypertriglyceridemic
mice. We propose that these alterations in liver lipid composition are related to the higher tissue and body metabolic rates
described in these hypertriglyceridemic mice. 相似文献
15.
I. V. Shmygol’ S. V. Snegir V. A. Pokrovskii 《Theoretical and Experimental Chemistry》2007,43(4):272-277
A comparative analysis of the laser desorption/ionization of vitamin B12 by matrix-assisted laser desorption/ionization (MALDI) and desorption/ionization on porous silicon (DIOS) was carried out.
The mass spectra obtained were interpreted and the pathways for ion formation and decomposition were established. The MALDI
fragmentation of the positive vitamin B12 ions is more extensive than the DIOS fragmentation. The most extensive fragmentation was found using the MALDI method for
negative vitamin B12 ions, which are lacking when using the DIOS method.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 251–256, July–August, 2007. 相似文献
16.
Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. The different gases are separated by specific columns but, if hydrogen (H2) is present in the sample, its detection can be performed by a thermal conductivity detector or a helium ionization detector. Indeed, coupled to GC, no other detector can perform this detection except the expensive atomic emission detector. Based on the detection and analysis of H2 isotopes by low‐pressure chemical ionization mass spectrometry (MS), a new method for H2 detection by GC coupled to MS with an electron ionization ion source and a quadrupole analyser is presented. The presence of H2 in a gaseous mixture could easily be put in evidence by the monitoring of the molecular ion of the protonated carrier gas. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
17.
Summary Capillary gas chromatography coupled to both mass spectrometry (GCMS) and atomic emission spectroscopy (GC-AED) was studied
for the analysis of bromine-containing alkylbenzenes present in sludge from a nickel refinery. Owing to the high abundance
of chlorinated compounds, location of the brominated species was difficult based on GC-MS with electron ionization. In contrast,
GC-MS with negative chemical ionization (GC-NCIMS) and GC-AED enabled bromine-selective detection and were utilized for an
effective location of the brominated compounds. Bromine-selective detection by GC-NCIMS relied on the monitoring of Br− (m/z 79/81) with CH4 as ionization gas, while atomic emission (827.2 nm) from a helium plasma was utilized in the case of GC-AED. While GC-NCIMS
was 30–500 times more sensitive than GC-AED, the latter technique was superior for quantitative purposes. Because the bromine
response of the AED was independent of molecular structure, quantification was possible without reference material. 相似文献
18.
An efficient microwave-assisted extraction (MAE) procedure coupled to gas chromatography–mass spectrometry (GC–MS) with electron
impact (EI) and chemical ionization (CI) has been developed to determine five organophosphate flame retardants (OPFRs) in
marine and river sediments. The effects of various operating parameters on the quantitative extraction of the OPFRs through
MAE were systematically investigated. Selected OPFRs were extracted from the sediments through MAE using 40 mL of acetone
at 120 °C for 20 min. The limits of quantitation ranged from 0.1 to 0.4 ng/g (dry weight) in 2 g of the sediment samples.
Moreover, as the chlorinated alkyl phosphates present no molecular ions in EI, GC–MS with furan-CI (furan-CI) was applied
to confirm their determination in complex environmental samples. The recoveries of the selected OPFRs in spiked sediment samples
ranged from 62% to 106% (relative standard derivation, 1−11%). The total concentrations of the selected OPFR residues in marine
and river sediments ranged from 1.0 to 12.6 ng/g. 相似文献
19.
Zhou L Zhao M Ennahar S Bindler F Marchioni E 《Analytical and bioanalytical chemistry》2012,403(1):291-300
A liquid chromatographic–electrospray ionization–tandem mass spectrometric (LC–ESI–MS2) method has been developed for determination of the molecular species of phosphatidylethanolamine (PE) in four food matrices
(soy, egg yolk, ox liver, and krill oil). The extraction and purification method consisted of a pressurized liquid extraction
procedure for total lipid (TL) extraction, purification of phospholipids (PLs) by adsorption on a silica gel column, and separation
of PL classes by semi-preparative normal-phase HPLC. Separation and identification of PE molecular species were performed
by reversed-phase HPLC coupled with electrospray ionization tandem mass spectrometry (ESI–MS2). Methanol containing 5 mmol L−1 ammonium formate was used as the mobile phase. A variety of PE molecular species were detected in the four food matrices.
(C16:0–C18:2)PE, (C18:2–C18:2)PE, and (C16:0–C18:1)PE were the major PE molecular species in soy. Egg yolk PE contained (C16:0–C18:1)PE,
(C18:0–C18:1)PE, (C18:0–C18:2)PE, and (C16:0–C18:2)PE as the major molecular species. Ox liver PE was rich in the species
(C18:0–C18:1)PE, (C18:0–C20:4)PE, and (C18:0–C18:2)PE. Finally, krill oil which was particularly rich in (C16:0(alkyl)–C22:6(acyl))plasmanylethanolamine
(PakE), (C16:0–C22:6)PE, and (C16:0–C20:5)PE, seemed to be an interesting potential source for supplementation of food with
eicosapentaenoic acid and docosahexaenoic acid. 相似文献
20.
Medina CM Pitarch E López FJ Vázquez C Hernández F 《Analytical and bioanalytical chemistry》2008,390(5):1343-1354
The potential of gas chromatography/tandem mass spectrometry with a triple quadrupole analyzer for determination of 12 polybrominated
diphenyl ethers in human breast tissues has been investigated. After extraction with hexane, two purification procedures-automated
normal-phase high-performance liquid chromatography and solid-phase extraction-were assayed. Both electron impact ionization,
in selected reaction monitoring mode, and negative chemical ionization, in selected ion recording mode, were tested for the
optimum determination of analytes. Isotopically labeled standards were added before extraction as surrogates: [13C]BDE47, [13C]BDE99 and [13C]BDE153 for electron impact ionization, and p,p′-DDE-d
8 for negative chemical ionization. The method was validated in terms of accuracy, precision, limits of detection and limits
of quantification, using human breast tissue spiked at three levels in the range 1–50 ng/g (5–250 ng/g for BDE209). The analytical
approach using solid-phase extraction cleanup followed by gas chromatography/mass spectrometry (negative chemical ionization
) led to lower detection limits (0.006–2 ng/g) and allowed the determination of the most problematic congener, BDE209, whose
poor sensitivity made difficult its determination at low residue levels. Special attention was given to the confirmation of
the compounds detected in samples in order to avoid reporting false positives. Two tandem mass spectrometry transitions or
three m/z ions were selected for each analyte when using electron impact ionization or negative chemical ionization modes, respectively.
In both cases, the transition to ion intensity ratio was used as a confirmation parameter. The method developed was applied
to the analysis of real human samples. Several brominated diphenyl ethers (congeners 47, 100, 99, 154, 153, 183 and 209) were
detected in the range 0.08–0.23 ng/g. 相似文献