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1.
Jackson SN Mishra S Murray KK 《Rapid communications in mass spectrometry : RCM》2004,18(18):2041-2045
Matrix-assisted laser desorption/ionization (MALDI) was used for the on-line analysis of single particles. An aerosol was generated at atmospheric pressure and particles were introduced into a time-of-flight (TOF) mass spectrometer through a single-stage differentially pumped capillary inlet. Prior to entering the mass spectrometer, a matrix was added to the particles using a heated saturator and condenser. A liquid matrix, 3-nitrobenzyl alcohol (NBA), and a solid matrix, picolinic acid (PA), were used. Particles were ablated with a 351 nm excimer laser and the resulting ions were mass-separated in a two-stage reflectron TOF mass spectrometer. Aerosol particles containing the biomolecules erythromycin and gramicidin S were analyzed with and without the matrix addition step. The addition of NBA to the particles resulted in mass spectra that contained an intact molecular ion mass peak. In contrast, PA-coated particles did not yield molecular ion peaks from matrix-coated particles. 相似文献
2.
A method of aerosol introduction for matrix-assisted laser desorption/ionization (MALDI) is described. The aerosol particles containing matrix and analyte enter directly into the aerosol time-of-flight mass spectrometer (ATOFMS) at atmospheric pressure. The scattered light signals from the aerosol particles are collected by a photomultiplier tube (PMT) and are passed on to an external electronic timing circuit, which determines particle size and is used to trigger a 266 nm pulsed Nd:YAG laser. The aerosol MALDI mass spectra and aerodynamic diameter of single particles can be obtained in real-time. Compared with other methods of liquid sample introduction, this method realizes detection of single particles and, more importantly, the sample consumption is lower. The effects of matrix-to-analyte ratio and laser pulse energy on analyte ion yield are examined. The optimal matrix-to-analyte ratio and laser energy are 50-110:1 and 200-400 μJ respectively. 相似文献
3.
4.
Kermit K. Murray David H. Russell 《Journal of the American Society for Mass Spectrometry》1994,5(1):1-9
A new method of liquid sample introduction for a time-of-flight mass spectrometer (TOF-MS) has been developed by applying the method of matrix-assisted laser desorption ionization to aerosols. Analyte biomolecules are dissolved in a methanol solvent along with a UVabsorbing matrix and formed into an aerosol with a pneumatic nebulizer. The aerosol particles are dried in a heated skimmer tube before ionization by pulsed 355-nm UV laser radiation. Mass analysis is achieved in a linear TOF-MS. Results for the ionization of bovine insulin (5733.5 Mw) are reported. 相似文献
5.
Stowers MA van Wuijckhuijse AL Marijnissen JC Scarlett B van Baar BL Kientz CE 《Rapid communications in mass spectrometry : RCM》2000,14(10):829-833
Matrix-assisted laser desorption/ionization (MALDI) mass spectra were obtained from single biological aerosol particles using an aerosol time-of-flight mass spectrometer (ATOFMS). The inlet to the ATOFMS was coupled with an evaporation/condensation flow cell that allowed the aerosol to be coated with matrix material as the sampled stream entered the spectrometer. Mass spectra were generated from aerosol composed either of gramicidin-S or erythromycin, two small biological molecules, or from aerosolised spores of Bacillus subtilis var niger. Three different matrices were used: 3-nitrobenzyl alcohol, picolinic acid and sinapinic acid. A spectrum of gramicidin-S was generated from approximately 250 attomoles of material using a molar ratio of 3-nitrobenzyl alcohol to analyte of approximately 20:1. A single peak, located at 1224 Da, was obtained from the bacterial spores. The washing liquid and extract solution from the spores were analyzed using electrospray mass spectrometry and subsequent MS/MS product ion experiments. This independent analysis suggests that the measured species represents part of the B. subtilis peptidoglycan. The on-line addition of matrix allows quasi-real-time chemical analysis of individual, aerodynamically sized particles, with an overall system residence time of less than 5 seconds. These results suggest that a MALDI-ATOFMS can provide nearly real-time identification of biological aerosols. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
6.
Influence Factors on Particle Growth for On-line Aerosol Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry 下载免费PDF全文
An evaporation/condensation flow cell was developed and interfaced with the matrix-assistedlaser desorption/ionization (MALDI) time-of-flight mass spectrometer for on-line bioaerosoldetection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the con-denser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of bi-ological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detec-tion that has the potential to provide rapid and reliable identification of airborne biological aerosols. 相似文献
7.
PENG Wei-xian 《高等学校化学研究》1996,12(1):44-49
IntroductionThemolecularweightofaproteinhasalwaysbeenrecognizedasanimpor-tantanalyticalparameterinbiochemistry.Sodiumdodecylsulfata-polyacry-lamidegelelectrophoresis(SDS-PAGE)isuniversallyusedtopurifyproteins,af-terseparationmo1ecularweightsareroutinelydeterminedbycomparisonofthemigrationrateoftheproteintobedeterminedtothatofasetofstandardpro-teins.However,ahighaccuracy(e.g.,to相似文献
8.
Solid phase microextraction with matrix assisted laser desorption/ionization introduction to mass spectrometry and ion mobility spectrometry 总被引:1,自引:0,他引:1
Solid phase microextraction (SPME) with matrix assisted laser desorption/ionization (MALDI) introduction was coupled to mass spectrometry and ion mobility spectrometry. Nicotine and myoglobin in matrix 2,5-dihydroxybenzonic acid (DHB), enkephalin and substance P in alpha-cyano-4-hydroxy cinnaminic acid were investigated as the target compounds. The tip of an optical fiber was silanized for extraction of the analytes of interest from solution. The optical fiber thus served as the sample extraction surface, the support for the sample plus matrix, and the optical pipe to transfer the laser energy from the laser to the sample. The MALDI worked under atmospheric pressure, and both an ion mobility spectrometer and a quadrupole/time-of-flight mass spectrometer were used for the detection of the SPME/MALDI signal. The spectra obtained demonstrate the feasibility of the SPME with MALDI introduction to mass spectrometry instrumentation. 相似文献
9.
Katalin F. Medzihradszky Gregory W. Adams Alma L. Burlingame Robert H. Bateman Martin R. Green 《Journal of the American Society for Mass Spectrometry》1996,7(1):1-10
This report describes the fragmentation processes for peptides induced by collisional activation of the 12C isobar of matrix-assisted laser desorption ionization (MALDI)-generated pseudomolecular ions employing an EBE orthogonal acceleration time-of-flight mass spectrometer and using xenon as the collision gas at a laboratory collision energy of 800 eV. These MALDI-collision-induced dissociation (CID) spectra are shown to provide sequence information of comparable quality to those obtained by using high energy CID conditions with liquid secondary ionization mass spectrometry on a four-sector tandem instrument. Peptide sequencing via MALDI-CID is demonstrated on three tryptic peptides obtained from a bacterial protein (P450 isozyme) of unknown sequence. Sensitivity is shown to be at the 1 pmol level for standard peptides. 相似文献
10.
Comparative MS/MS studies of singly and doubly charged electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) precursor peptide ions are described. The spectra from these experiments have been evaluated with particular emphasis on the data quality for subsequent data processing and protein/amino acid sequence identification. It is shown that, once peptide ions are formed by ESI or MALDI, their charge state, as well as the collision energy, is the main parameter determining the quality of collision-induced dissociation (CID) MS/MS fragmentation spectra of a given peptide. CID-MS/MS spectra of singly charged peptides obtained on a hybrid quadrupole orthogonal time-of-flight mass spectrometer resemble very closely spectra obtained by matrix-assisted laser desorption/ionization post-source decay time-of-flight mass spectrometry (MALDI-PSD-TOFMS). On the other hand, comparison of CID-MS/MS spectra of either singly or doubly charged ion species shows no dependence on whether ions have been formed by ESI or MALDI. This observation confirms that, at the time of precursor ion selection, further mass analysis is effectively decoupled from the desorption/ionization event. Since MALDI ions are predominantly formed as singly charged species and ESI ions as doubly charged, the associated difference in the spectral quality of MS/MS spectra as described here imposes direct consequences on data processing, database searching using ion fragmentation data, and de novo sequencing when ionization techniques are changed. 相似文献
11.
Bogan MJ Patton E Srivastava A Martin S Fergenson DP Steele PT Tobias HJ Gard EE Frank M 《Rapid communications in mass spectrometry : RCM》2007,21(7):1214-1220
The analysis of poly(ethylene glycol) (PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption/ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG-containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight<500 Da generated mass spectra reminiscent of mass spectra of PEG collected by other mass spectrometer platforms including the characteristic distribution of positive ions (Na+ adducts) separated by the 44 m/z units of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight>500 Da were detected from particles that also contained the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in the optimization of our bioaerosol mass spectrometers for the application of measurements of complex biological samples, including human effluents, and we recommend that the same strategies will be of great utility to the development of any online aerosol LDI mass spectrometer platform. 相似文献
12.
Loboda AV Ackloo S Chernushevich IV 《Rapid communications in mass spectrometry : RCM》2003,17(22):2508-2516
A high-performance orthogonal time-of-flight (TOF) mass spectrometer was developed specifically for use in combination with a matrix-assisted laser desorption/ionization (MALDI) source. The MALDI source features an ionization region containing a buffer gas with variable pressure. The source is interfaced to the TOF section via a collisional focusing ion guide. The pressure in the source influences the rate of cooling and allows control of ion fragmentation. The instrument provides uniform resolution up to 18,000 FWHM (full width at half maximum). Mass accuracy routinely achieved with a single-point internal recalibration is below 2 ppm for protein digest samples. The instrument is also capable of recording spectra of samples containing compounds with a broad range of masses while using one set of experimental conditions and without compromising resolution or mass accuracy. 相似文献
13.
Ma Y Lu Y Zeng H Ron D Mo W Neubert TA 《Rapid communications in mass spectrometry : RCM》2001,15(18):1693-1700
A two-step mass spectrometric method for characterization of phosphopeptides from peptide mixtures is presented. In the first step, phosphopeptide candidates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) based on their higher relative intensities in negative ion MALDI spectra than in positive ion MALDI spectra. The detection limit for this step was found to be 18 femtomoles or lower in the case of unfractionated in-solution digests of a model phosphoprotein, beta-casein. In the second step, nanoelectrospray tandem mass (nES-MS/MS) spectra of doubly or triply charged precursor ions of these candidate phosphopeptides were obtained using a quadrupole time-of-flight (Q-TOF) mass spectrometer. This step provided information about the phosphorylated residues, and ruled out nonphosphorylated candidates, for these peptides. After [(32)P] labeling and reverse-phase high-performance liquid chromatography (RP-HPLC) to simplify the mixtures and to monitor the efficiency of phosphopeptide identification, we used this method to identify multiple autophosphorylation sites on the PKR-like endoplasmic reticulum kinase (PERK), a recently discovered mammalian stress-response protein. 相似文献
14.
B. D. Morrical D. P. Fergenson K. A. Prather 《Journal of the American Society for Mass Spectrometry》1998,9(10):1068-1073
Analysis of organic compounds in aerosol particles using real-time single particle techniques is difficult because of extensive fragmentation that occurs in the laser desorption/ionization step. In an effort to avoid such fragmentation processes, we coupled a “soft” two-step laser desorption/ionization technique (L2MS) with aerosol time-of-flight mass spectrometry (ATOFMS). In these studies, we find this combination preserves intact organic molecules while providing the real-time mass spectra of suspended aerosol particles. Mass spectra of particles analyzed by one-step desorption mass spectrometry and L2MS are presented for comparison. These include 2,4-dihydroxybenzoic acid as a test case and wood and cigarette combustion particles as real world examples. This is the first published demonstration of L2MS performed on single particles not deposited on a substrate prior to analysis. 相似文献
15.
B Spengler Y Pan R J Cotter L S Kan 《Rapid communications in mass spectrometry : RCM》1990,4(4):99-102
A Wiley-McLaren type time-of-flight mass spectrometer has been used for molecular weight measurements of several unprotected oligodeoxyribonucleotides using matrix-assisted UV laser desorption. Approximately 10 to 100 pmol of sample was required for recording their positive-ion mass spectra with a mass resolution in the range of 150 to 300 (Full width at half maximum) (FWHM). Little fragmentation was observed. 相似文献
16.
T Keough M P Lacey R J Strife 《Rapid communications in mass spectrometry : RCM》2001,15(23):2227-2239
Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) and ion trap mass spectrometry have been used to study the fragmentation behavior of native peptides and peptide derivatives prepared for de novo sequencing applications. Sulfonic acid derivatized peptides were observed to fragment more extensively and up to 28 times more efficiently than the corresponding native peptides. Tandem mass spectra of native peptides containing aspartic or glutamic acids are dominated by cleavage on the C-terminal side of the acidic residues. This significantly limits the amount of sequence information that can be derived from those compounds. The MS/MS spectra of native tryptic peptides containing oxidized Met residues show extensive loss of CH(3)SOH and little sequence-specific fragmentation. On the other hand, the tandem mass spectra of derivatized peptides containing Asp, Glu and oxidized Met show much more uniform fragmentation along the peptide backbone. The AP-MALDI tandem mass spectra of some derivatized peptides were shown to be qualitatively very similar to the corresponding vacuum MALDI postsource decay mass spectra, which were obtained on a reflector time-of-flight instrument. However, the ion trap mass spectrometer offers several advantages for peptide sequencing relative to current reflector time-of-flight instruments including improved product ion mass measurement accuracy, improved precursor ion selection and MS(n). These latter capabilities were demonstrated with solution digests of model proteins and with in-gel digests of 2D-gel separated proteins. 相似文献
17.
Marcela M. Cordero Timothy J. Cornish Robert J. Cotter 《Journal of the American Society for Mass Spectrometry》1996,7(6):590-597
Atandem reflectron time-of-flight mass spectrometer developed in our laboratory provides a unique opportunity to investigate the collision-induced dissociation of fullerene ions formed by matrix-assisted laser desorption/ionization (MALDI). Specifically, this opportunity arises from the ability to utilize high energy collisional activation (normally available only on tandem sector instruments by using continuous ionization techniques) for ions formed by pulsed laser desorption, whereas most MALDI time-of-flight instruments record product ion mass spectra of ions formed by metastable or postsource decay. In this study we investigate the products of mass-selected and collisionally activated C 60 + and C 70 + ions by using different target gases over a range of target gas pressures. In general, heavier target gases produce more extensive fragmentation and improve the mass resolution of lower mass ionic products because a greater portion of these ions are formed by single collisions. Additionally, the tandem time-of-flight instrument utilizes a nonlinear (curved-field) reflectron in the second mass analyzer that enables high energy collision-induced dissociation spectra to be recorded without scanning or stepping the reflectron voltage. 相似文献
18.
Matrix-assisted laser desorption/ionization of high-mass molecules by Fourier-transform mass spectrometry. 总被引:1,自引:0,他引:1
Following the first demonstrations of high-mass analysis using time-of-flight matrix-assisted laser desorption/ionization (MALDI) techniques by Hillenkamp, Tanaka and their co-workers, there have been significant efforts in a number of laboratories to adapt the new methodology to Fourier-transform mass spectrometry (FTMS). The motivation for this research is obvious. Namely, it would be desirable to couple the unparalleled high mass resolution of FTMS with the extended mass range provided by MALDI, particularly for analysis of polymers and biomolecules. Unfortunately, prior to the present work, attempts to mate FTMS and MALDI have met with limited success. The highest mass matrix-assisted laser-desorption-FTMS result previously obtained appears to be the unpublished low resolution spectrum of bovine insulin recently reported by Russell and co-workers. We, Campana and co-workers, and Hettich and Buchanan have had some success with MALDI-FTMS of biomolecules with masses lower than 3000 Da, including melittin, a variety of lower mass peptides, and oligonucleotides with masses lower than 1800 Da. Furthermore, with the single exception of Campana's report of obtaining mass resolution of 5000 for the molecular ion of melittin, such spectra have not displayed high resolution. Here, we report successful development of MALDI-FTMS, demonstrated with spectra obtained from a variety of high-mass polymer and biomolecule samples, using 355 nm radiation from an excimer-pumped dye laser for desorption/ionization and sinapinic acid as matrix. Some of these spectra are of much higher mass resolution than is possible with current time-of flight mass spectrometers. 相似文献
19.
Continuous flow matrix-assisted laser desorption/ionization (MALDI) was demonstrated with infrared laser desorption and an ethanol matrix. A capillary was used to deliver an analyte solution dissolved in ethanol to a metal frit embedded in a sample stage. Typical flow rates were 1.7&mgr;L/min. An optical parametric oscillator tuned to 2.8&mgr;m was used for desorption and ionization, and mass analysis was achieved with a 1 m linear time-of-flight mass spectrometer. Flow injection studies were performed with low picomolar quantities of insulin and myoglobin in solutions containing 0.1 to 1.0% glycerol in ethanol. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
20.
Loboda AV Krutchinsky AN Bromirski M Ens W Standing KG 《Rapid communications in mass spectrometry : RCM》2000,14(12):1047-1057
A matrix-assisted laser desorption/ionization (MALDI) source has been coupled to a tandem quadrupole/time-of-flight (QqTOF) mass spectrometer by means of a collisional damping interface. Mass resolving power of about 10,000 (FWHM) and accuracy in the range of 10 ppm are observed in both single-MS mode and MS/MS mode. Sub-femtomole sensitivity is obtained in single-MS mode, and a few femtomoles in MS/MS mode. Both peptide mass mapping and collision-induced dissociation (CID) analysis of tryptic peptides can be performed from the same MALDI target. Rapid spectral acquisition (a few seconds per spectrum) can be achieved in both modes, so high throughput protein identification is possible. Some information about fragmentation patterns was obtained from a study of the CID spectra of singly charged peptides from a tryptic digest of E. coli citrate synthase. Reasonably successful automatic sequence prediction (>90%) is possible from the CID spectra of singly charged peptides using the SCIEX Predict Sequence routine. Ion production at pressures near 1 Torr (rather than in vacuum) is found to give reduced metastable fragmentation, particularly for higher mass molecular ions. Copyright 2000 John Wiley & Sons, Ltd. 相似文献