金属加工助剂是金属加工生产过程中必不可少的化工产品,其组成复杂,易形成螯合物干扰成分分析。该文利用傅立叶变换离子回旋共振质谱(Fourier transform ion cyclotron resonance mass spectrometry,FT-ICR MS)技术的高分辨性能,结合电感耦合等离子体质谱(ICP-MS)、红外光谱(IR)和核磁共振谱(NMR)对一种含未知成分的金属加工助剂进行成分分析。结果表明,该金属加工助剂中含有柠檬酸钠、乙二胺四乙酸(EDTA)与金属铋螯合物。该方法简便、准确,适用于含有金属螯合物的金属加工助剂成分的快速鉴定。 相似文献
The most common data collection in shotgun proteomics is via data-dependent acquisition (DDA), a process driven by an automated instrument control routine that directs MS/MS acquisition from the highest abundant signals to the lowest. An alternative to DDA is data-independent acquisition (DIA), a process in which a specified range in m/z is fragmented without regard to prioritization of a precursor ion or its relative abundance in the mass spectrum, thus potentially offering a more comprehensive analysis of peptides than DDA. In this work, we evaluate both DDA and DIA on three different linear ion trap instruments: an LTQ, an LTQ modified with an electrodynamic ion funnel, and an LTQ Velos. These instruments represent both older (LTQ) and newer (LTQ Velos) ion trap designs (i.e., linear versus dual ion traps, respectively), and allow direct comparison of peptide identifications using both DDA and DIA analysis. Further, as the LTQ Velos has an enhanced “S-lens” ion guide to improve ion flux, we found it logical to determine if the former LTQ model could be leveraged by improving sensitivity by modifying with an electrodynamic ion guide of significantly different design to the S-lens. We find that the ion funnel enabled LTQ identifies more proteins in the insoluble fraction of a yeast lysate than the other two instruments in DIA mode, whereas the faster scanning LTQ Velos performs better in DDA mode. We explore reasons for these results, including differences in scan speed, source ion optics, and linear ion trap design. Graphical Abstract
We provide the initial performance evaluation of a 21 Tesla Fourier transform ion cyclotron resonance mass spectrometer operating at the Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory. The spectrometer constructed for the 21T system employs a commercial dual linear ion trap mass spectrometer coupled to a FTICR spectrometer designed and built in-house. Performance gains from moving to higher magnetic field strength are exemplified by the measurement of peptide isotopic fine structure, complex natural organic matter mixtures, and large proteins. Accurate determination of isotopic fine structure was demonstrated for doubly charged Substance P with minimal spectral averaging, and 8158 molecular formulas assigned to Suwannee River Fulvic Acid standard with root-mean-square (RMS) error of 10 ppb. We also demonstrated superior performance for intact proteins; namely, broadband isotopic resolution of the entire charge state distribution of apo-transferrin (78 kDa) and facile isotopic resolution of monoclonal antibody under a variety of acquisition parameters (e.g., 6 s time-domains with absorption mode processing yielded resolution of approximately 1 M at m/z?=?2700).
We report the first charge reversal experiments performed by tandem-in-time rather than tandem-in-space MS/MS. Precursor odd-electron anions from fullerene C60, and even-electron ions from 2,7-di-tert-butylfluorene-9-carboxylic acid and 3,3′-bicarbazole were converted into positive product ions (–CR+) inside the magnet of a Fourier transform ion cyclotron resonance mass spectrometer. Charge reversal was activated by irradiating precursor ions with high energy electrons or UV photons: the first reported use of those activation methods for charge reversal. We suggest that high energy electrons achieve charge reversal in one step as double electron transfer, whereas UV-activated –CR+ takes place stepwise through two single electron transfers and formally corresponds to a neutralization-reionization (–NR+) experiment.相似文献
The presence of dissolved metal ions in waters associated with crude oils has many negative implications for the transport, processing, and refining of petroleum. In addition, mass spectrometric analysis of sodium containing crude oil samples suffers from ionization suppression, unwanted adduct formation, and an increase in the complexity of data analysis. Here, we describe a method for the reduction/elimination of these adverse effects by modification of the source region gas-inlet system of a 12 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Several acids were examined as part of this study, with the most suitable for on-line desalting found to have both high vapor pressure and low pKa; 12.1 M HCl showed the strongest desalting effect for crude oil samples with a sodium removal index (SRI) of 88%–100% ± 7% for the NaOS compound class. In comparison, a SRI of only 38% ± 9% was observed for a H2O/toluene solution-phase extraction of Oil 1. These results clearly demonstrate the increased efficacy of pseudo-vapor phase desalting with the additional advantages that initial sample solution conditions are preserved and no sample preparation is required prior to analysis.
A new type of combination ion source has been devised. It unites two complementary ionization methods, i.e., liquid injection
field desorption/ionization (LIFDI) and electrospray ionization (ESI). This LIFDI-ESI combination ion source has been constructed
for a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The LIFDI-ESI combination ion source can be switched
between the LIFDI and ESI modes of operation within 15 min without breaking the vacuum. The source design and its operation
are described. LIFDI-FT-ICR spectra of the ionic liquid trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl)-trifluorophosphate,
polyethylene glycol 600, 2,3,4-tridodecyloxy-benzaldehyde, and [60]fullerene are described. 相似文献
FT-ICR mass spectrometry has been limited to magnitude mode for almost 40 years due to the data processing methods used. However,
it is well known that phase correction of the data can theoretically produce an absorption-mode spectrum with a mass-resolving
power that is as much as twice as high as conventional magnitude mode, and that it also improves the quality of the peak shape.
Temporally dispersed frequency sweep excitation followed by a time delay before detection results in a steep quadratic variation
in the signal phase with frequency. Viewing this, it is possible to find the correct phase function by performing a quadratic
least squares fit, modified by iterating through phase cycles until the correct quadratic function is found. Here, we present
a robust manual method to rotate these signals mathematically and generate a “phased” absorption-mode spectrum. The method
can, in principle, be automated. Baseline correction is also included to eliminate the accompanying baseline drift. The resulting
experimental FT-ICR absorption-mode spectra exhibit a resolving power that is at least 50% higher than that of the magnitude
mode. 相似文献
The extent of internal energy deposition into ions upon storage, radial ejection, and detection using a linear quadrupole ion trap mass spectrometer is investigated as a function of ion size (m/z 59 to 810) using seven ion-molecule thermometer reactions that have well characterized reaction entropies and enthalpies. The average effective temperatures of the reactants and products of the ion-molecule reactions, which were obtained from ion-molecule equilibrium measurements, range from 295 to 350 K and do not depend significantly on the number of trapped ions, m/z value, ion trap qz value, reaction enthalpy/entropy, or the number of vibrational degrees of freedom for the seven reactions investigated. The average of the effective temperature values obtained for all seven thermometer reactions is 318?±?23 K, which indicates that linear quadrupole ion trap mass spectrometers can be used to study the structure(s) and reactivity of ions at near ambient temperature.
Several lignin model compounds were examined to test whether gas-phase ion–molecule reactions of trimethylborate (TMB) in
a FTICR can be used to differentiate the ortho-, meta-, and para-isomers of protonated aromatic compounds, such as those formed during degradation of lignin. All three regioisomers could
be differentiated for methoxyphenols and hydroxyphenols. However, only the differentiation of the ortho-isomer from the meta- and para-isomers was possible for hydroxyacetophenones and hydroxybenzoic acids. Consideration of the previously reported proton affinities
at all basic sites in the isomeric hydroxyphenols, and the calculated proton affinities at all basic sites in the three methoxyphenol
isomers, revealed that the proton affinities of the analytes relative to that of TMB play an important role in determining
whether and how they react with TMB. The loss of two methanol molecules (instead of one) from the adducts formed with TMB
either during ion–molecule reactions, or during sustained-off resonance irradiated collision-activated dissociation of the
ion–molecule reaction products, revealed the presence of two functionalities in almost all the isomers. This finding supports
earlier results suggesting that TMB can be used to count the functionalities in unknown oxygen-containing analytes. 相似文献
