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1

Atmospheric Monitoring With Chemical Ionisation Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) and Future Developments: Hadamard Transform Mass Spectrometry  

Microsoft Academic Search

Chemical ionisation reaction mass spectrometry (CIR-MS) is a more general version of proton transfer reaction mass spectrometry\\u000a (PTR-MS) in which alternative chemical ionisation schemes are possible. This concept has been realised in a new instrument\\u000a based on time-of-fl ight mass spectrometry (TOF-MS) and has been applied to the measurement of a range of trace atmospheric\\u000a volatile organic compounds (VOCs) and

Kevin P. Wyche; Christopher Whyte; Robert S. Blake; Rebecca L. Cordell; Kerry A. Willis; Andrew M. Ellis; Paul S. Monks

2

Limits for the detection of (poly-)phosphoinositides by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS)  

Microsoft Academic Search

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been recently established as a powerful tool for the analysis of biomolecules. Here, MALDI-TOF MS was used for the detection of (poly-)phosphoinositides (PPI). PPI possess higher molecular weights than other phospholipids and a high phosphorylation-dependent negative charge. Both features affect the MALDI detection limits expressed as the minimum of

Matthias Müller; Jürgen Schiller; Marijana Petkovi?; Wolf Oehrl; Regina Heinze; Reinhard Wetzker; Klaus Arnold; Jürgen Arnhold

2001-01-01

3

Analysis of Phospholipid Mixtures from Biological Tissues by Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): A Laboratory Experiment  

ERIC Educational Resources Information Center

|Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to investigate the phospholipid (PL) compositions of tissues and body fluids, often without previous separation of the total mixture into the individual PL classes. Therefore, the questions of whether all PL classes are detectable…

Eibisch, Mandy; Fuchs, Beate; Schiller, Jurgen; Sub, Rosmarie; Teuber, Kristin

2011-01-01

4

[Performance of two matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) models for identification of bacteria isolated from blood culture].  

PubMed

We compared the results of two bacterial identification methods: 1) a traditional method based on phenotypic identification of the causative organism using gram-staining, culture and biochemical markers and 2) matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A total of 111 isolates, including 107 strains of common bacteria species and 4 strains of 3 yeast species, were tested by the traditional method and MALDI-TOF MS method(VITEK MS and Micro flex LT). Data obtained using MALDI-TOF MS were classified as Level 1 and Level 2 according to the confidence level of identification results from the VITEK MS ver. 1.0 database (VITEK MS) and MALDI Biotyper ver. 2.0 database (Microflex LT). The proportions of measured samples identified as Level 1 were 98.2% with the VITEK MS database and 87.4% with the MALDI Biotyper database. The concordance rates of the traditional method were 93.7% with the VITEK MS database and 82.0% with the MALDI Biotyper database. Identification results of five strains were mismatched between the traditional method and MALDI-TOF MS. Their ribosomal RNA sequences were identical to the results obtained from MALDI-TOF MS. We concluded that the performance of VITEK MS is superior to that of the traditional method and Microflex LT. PMID:23947175

Itoh, Eisuke; Watari, Tomohisa; Azuma, Yuka; Watanabe, Naoki; Tomoda, Yutaka; Akasaka, Kazumi; Kino, Shuichi

2013-05-01

5

Evaluation of two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems for the identification of Candida species.  

PubMed

Candida spp. are responsible for severe infections in immunocompromised patients and those undergoing invasive procedures. The accurate identification of Candida species is important because emerging species can be associated with various antifungal susceptibility spectra. Conventional methods have been developed to identify the most common pathogens, but have often failed to identify uncommon species. Several studies have reported the efficiency of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of clinically relevant Candida species. In this study, we evaluated two commercially available MALDI-TOF systems, Andromas™ and Bruker Biotyper™, for Candida identification in routine diagnosis. For this purpose, we investigated 1383 Candida isolates prospectively collected in eight hospital laboratories during routine practice. MALDI-TOF MS results were compared with those obtained using conventional phenotypic methods. Analysis of rDNA gene sequences with internal transcribed regions or D1-D2 regions is considered the reference standard for identification. Both MALDI-TOF MS systems could accurately identify 98.3% of the isolates at the species level (1359/1383 for Andromas™; 1360/1383 for Bruker Biotyper™) vs. 96.5% for conventional techniques. Furthermore, whereas conventional methods failed to identify rare or emerging species, these were correctly identified by MALDI-TOF MS. Both MALDI-TOF MS systems are accurate and cost-effective alternatives to conventional methods for mycological identification of clinically relevant Candida species and should improve the diagnosis of fungal infections as well as patient management. PMID:23594150

Lacroix, C; Gicquel, A; Sendid, B; Meyer, J; Accoceberry, I; François, N; Morio, F; Desoubeaux, G; Chandenier, J; Kauffmann-Lacroix, C; Hennequin, C; Guitard, J; Nassif, X; Bougnoux, M-E

2013-03-01

6

A direct and simple method of coupling matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) to thin-layer chromatography (TLC) for the analysis of phospholipids from egg yolk  

Microsoft Academic Search

Although the most important application of matrix-assisted laser desorption and ionization time-of-flight mass spectrometry\\u000a (MALDI-TOF MS) is “proteomics,” there is growing evidence that this soft ionization method is also useful for phospholipid\\u000a (PL) analysis. Although all PLs are detectable by MALDI-TOF MS, some lipid classes, particularly those with quaternary amines\\u000a such as phosphatidylcholines (PCs), are more sensitively detected than others,

Beate Fuchs; Jürgen Schiller; Rosmarie Süß; Martin Schürenberg; Detlev Suckau

2007-01-01

7

Identification of five gelatins by ultra performance liquid chromatography/time-of-flight mass spectrometry (UPLC/Q-TOF-MS) using principal component analysis.  

PubMed

An ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC/Q-TOF-MS) method coupled with a principal component analysis (PCA) was developed and applied toward identifying donkey-hide gelatin, bovine-hide gelatin, pig-hide gelatin, tortoise shell glue, and deerhorn glue. The UPLC-MS data of the trypsin digested samples were subjected to principal component analysis (PCA) in order to classify these five gelatins. Additionally, marker peptides given by the loadings plot of PCA were identified based on a comparison of recorded LC-MS data with a previously reported database of the corresponding gelatin variants. The results from this study indicate that the proposed method is reliable, and it has been successfully applied to the identification of variants of gelatins commonly used in Traditional Chinese Medicine (TCM). PMID:22257536

Cheng, Xian-Long; Wei, Feng; Xiao, Xin-Yue; Zhao, Ying-Yong; Shi, Yan; Liu, Wei; Zhang, Ping; Ma, Shuang-Cheng; Tian, Shou-Sheng; Lin, Rui-Chao

2011-12-29

8

Liquid chromatography\\/time-of-flight\\/mass spectrometry (LC\\/TOF\\/MS) for the analysis of emerging contaminants  

Microsoft Academic Search

In this review, we focus on the importance of unequivocally detecting emerging contaminants, as well as establishing their presence in the environment by accurate mass spectrometric measurement techniques. The environmental issue of emerging contaminants is tied to the analysis of wastewater samples using the new analytical methods of the last decade, especially liquid chromatography coupled to tandem mass spectrometry (LC\\/MS\\/MS)

E. Michael Thurman

2003-01-01

9

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization re- action time-of-flight mass spectrometer (CIR-TOF-MS) util- ising the environment chamber SAPHIR (Simulation of At- mospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Julich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composi- tion and Change the European NeTwork for excellence) sup- ported oxygenated volatile organic compound (OVOC)

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. C. Apel

2007-01-01

10

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005.

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. C. Apel

2007-01-01

11

Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber - Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. Apel

2006-01-01

12

Detection of aqueous phase chemical warfare agent degradation products by negative mode ion mobility time-of-flight mass spectrometry [IM(tof)MS  

Microsoft Academic Search

The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass\\u000a spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined.\\u000a Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified\\u000a reference materials (CRM) of CWA degradation products for the detection

Wes E. Steiner; Charles S. Harden; Feng Hong; Steve J. Klopsch; Vincent M. McHugh

2006-01-01

13

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

NASA Astrophysics Data System (ADS)

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0-0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+) as the primary chemical ionization (CI) reagent in order to facilitate proton transfer to the analyte OVOCs. The results presented show that the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs at mixing ratios of around 10 ppbV in "real-time" (i.e. detection on the one-minute time scale), with sub-ppbV measurement also achieved following an increase in averaging time to tens of minutes. It is shown that in general OVOC measurement is made with high accuracy and precision, with integration time, mixing ratio and compound dependent values as good as 4-13% and 3-15% respectively. It is demonstrated that CIR-TOF-MS has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurement.

Wyche, K. P.; Blake, R. S.; Ellis, A. M.; Monks, P. S.; Brauers, T.; Koppmann, R.; Apel, E. C.

2007-02-01

14

Comparative proteomic profiles of Aspergillus fumigatus and Aspergillus lentulus strains by surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS)  

PubMed Central

Background Surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS) was applied to analyze the protein profiles in both somatic and metabolic extracts of Aspergillus species. The study was carried out on some Aspergillus species within the Fumigati section (Aspergillus fumigatus wild-types and natural abnormally pigmented mutants, and Aspergillus lentulus). The aim was to validate whether mass spectrometry protein profiles can be used as specific signatures to discriminate different Aspergillus species or even mutants within the same species. Results The growth conditions and the SELDI-TOF parameters were determined to generate characteristic protein profiles of somatic and metabolic extracts of Aspergillus fumigatus strains using five different ProteinChips®, eight growth conditions combining two temperatures, two media and two oxygenation conditions. Nine strains were investigated: three wild-types and four natural abnormally pigmented mutant strains of A. fumigatus and two strains of A. lentulus. A total of 242 fungal extracts were prepared. The spectra obtained are protein signatures linked to the physiological states of fungal strains depending on culture conditions. The best resolutions were obtained using the chromatographic surfaces CM10, NP20 and H50 with fractions of fungi grown on modified Sabouraud medium at 37°C in static condition. Under these conditions, the SELDI-TOF analysis allowed A. fumigatus and A. lentulus strains to be grouped into distinct clusters. Conclusions SELDI-TOF analysis distinguishes A. fumigatus from A. lentulus strains and moreover, permits separate clusters of natural abnormally pigmented A. fumigatus strains to be obtained. In addition, this methodology allowed us to point out fungal components specifically produced by a wild-type strain or natural mutants. It offers attractive potential for further studies of the Aspergillus biology or pathogenesis.

2011-01-01

15

Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

NASA Astrophysics Data System (ADS)

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber - Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0-0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+) as the primary chemical ionization (CI) reagent in order to facilitate proton transfer to the analyte OVOCs. The results show the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs down to sub-ppbV mixing ratios with high accuracy and precision. It is demonstrated that the technique has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurements.

Wyche, K. P.; Blake, R. S.; Ellis, A. M.; Monks, P. S.; Brauers, T.; Koppmann, R.; Apel, E.

2006-10-01

16

Detection of aqueous phase chemical warfare agent degradation products by negative mode ion mobility time-of-flight mass spectrometry [IM(tof)MS].  

PubMed

The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined. Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified reference materials (CRM) of CWA degradation products for the detection of Schedule 1, 2, or 3 toxic chemicals or their precursors as defined by the chemical warfare convention (CWC) treaty verification were used in this study. A mixture of six G-series nerve related CWA degradation products (EMPA, IMPA, EHEP, IHEP, CHMPA, and PMPA) and their related collision induced dissociation (CID) fragment ions (MPA and EPA) were found in each case to be clearly resolved and detected using the IM(tof)MS instrument in negative ion monitoring mode. Corresponding ions, masses, drift times, K(o) values, and signal intensities for each of the CWA degradation products are reported. PMID:16413205

Steiner, Wes E; Harden, Charles S; Hong, Feng; Klopsch, Steve J; Hill, Herbert H; McHugh, Vincent M

2006-01-18

17

Optimization of Campylobacter growth conditions for further identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).  

PubMed

Growth conditions - including growth medium and incubation temperature - may influence the identification of Campylobacter by MALDI-TOF MS. For each bacterial species, medical microbiologists should be aware of such potential influences on spectral data before analyzing and interpreting MALDI-TOF MS results. PMID:23811211

Martiny, Delphine; Visscher, Alain; Catry, Boudewijn; Chatellier, Sonia; Vandenberg, Olivier

2013-06-26

18

Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing.  

PubMed

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated. PMID:22644155

Adam, T W; Clairotte, M; Streibel, T; Elsasser, M; Pommeres, A; Manfredi, U; Carriero, M; Martini, G; Sklorz, M; Krasenbrink, A; Astorga, C; Zimmermann, R

2012-05-30

19

Rapid identification of betacyanins from Amaranthus tricolor, Gomphrena globosa, and Hylocereus polyrhizus by matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS).  

PubMed

Natural betacyanins have attracted great attention as food colorants and potential antioxidants. Matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS) is a new and powerful technique for the identification of low molecular weight compounds. This study is the first to employ MALDI-QIT-TOF MS to rapidly identify, within a few minutes, a great number of betacyanins in crude extracts from Amaranthus tricolor seedlings, Gomphrena globosa flowers, and Hylocereus polyrhizus fruits. The fresh crude extract samples without any purification were directly used for MALDI-QIT-TOF MS analysis with 2,5-dihydroxybenzoic acid as a matrix. The MS2 and MS3 spectrometric data acquired could provide important characteristic information for structural elucidation of the betacyanins. Fourteen free and acylated betacyanins, belonging to amaranthin-type, betanin-type, and gomphrenin-type betacyanins, respectively, were identified. However, the related isomers should be differentiated with the aid of HPLC. PMID:16939305

Cai, Yi-Zhong; Xing, Jie; Sun, Mei; Corke, Harold

2006-09-01

20

Sensomics Analysis of Key Hazelnut Odorants ( Corylus avellana L. 'Tonda Gentile') Using Comprehensive Two-Dimensional Gas Chromatography in Combination with Time-of-Flight Mass Spectrometry (GC×GC-TOF-MS).  

PubMed

Comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) has been used a few times to identify and quantitate single aroma-active compounds, but the capability of this technique to monitor a complete set of key odorants evoking the aroma of a given food in one run has not been exploited so far. A fast, multiodorant analysis using GC×GC-TOF-MS in combination with stable isotope dilution assays (SIDA) was developed to quantitate the entire set of aroma compounds, the sensometabolome, of raw and roasted hazelnuts ( Corylus avellana L. 'Tonda Gentile') previously established by GC-olfactometry. The capability of the method to evaluate the aroma contribution of each sensometabolite was evaluated by introducing a new term, the limit of odor activity value (LOAV), indicating whether a given aroma compound can be determined down to an odor activity value (OAV) of 1 (odor activity value = ratio of concentration to odor threshold). The advantage of the new method was proven by comparing the performance parameters with a traditional one-dimensional approach using GC-ion trap mass-spectrometry (GC-IT-MS). The results showed that the detector linearity and sensitivity of GC×GC-TOF-MS was on average higher by a factor of 10 compared to GC-IT-MS, thus enabling the quantitation of the aroma relevant amounts of 22 key odorants of hazelnuts in one run of the 30 aroma-active compounds. Seven novel isotopically labeled internal standards were synthesized to meet the analytical requirements defined by electron impact ionization in TOF-MS, that is, to keep the label. On the basis of the quantitative results obtained, it was possible to closely mimic the aroma of raw and roasted 'Tonda Gentile' hazelnuts by preparing an aroma recombinate containing the key odorants at their natural concentrations occurring in the nuts. PMID:23663170

Kiefl, Johannes; Pollner, Gwendola; Schieberle, Peter

2013-05-21

21

Analysis of the chemical composition of the essential oil of Polygonum minus Huds. using two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-TOF MS).  

PubMed

The essential oil in leaves of Polygonum minus Huds., a local aromatic plant, were identified by a pipeline of gas chromatography (GC) techniques coupled with mass-spectrometry (MS), flame ionization detector (FID) and two dimensional gas chromatography time of flight mass spectrometry (GC x GC-TOF MS). A total of 48 compounds with a good match and high probability values were identified using this technique. Meanwhile, 42 compounds were successfully identified in this study using GC-MS, a significantly larger number than in previous studies. GC-FID was used in determining the retention indices of chemical components in P. minus essential oil. The result also showed the efficiency and reliability were greatly improved when chemometric methods and retention indices were used in identification and quantification of chemical components in plant essential oil. PMID:20944520

Baharum, Syarul Nataqain; Bunawan, Hamidun; Ghani, Ma'aruf Abd; Mustapha, Wan Aida Wan; Noor, Normah Mohd

2010-10-12

22

Surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI TOF-MS) and ProteinChip ® technology in proteomics research  

Microsoft Academic Search

In this review article, we describe some of the studies that have been performed using the surface-enhanced laser desorption ionization (SELDI) time-of-flight mass spectrometry and ProteinChip® technology over the past few years, and highlight both their findings as well as limitations. Proteomic applications, such as target or marker identification and target validation or toxicology, will be addressed. We will also

Volker Seibert; Andreas Wiesner; Thomas Buschmann; Jörn Meuer

2004-01-01

23

Accelerator-Based Surface Chemistry by Combined Time-of-Flight Mass Spectrometry (TOF-MS) and Particle-Induced X-Ray Emission (PIXE)  

SciTech Connect

We describe the development of a new capability for performing microscopic chemical analysis in the near surface of a sample. The technology uses a focused high-energy ion beam from an accelerator to cause characteristic elemental x-rays to be emitted and, simultaneously, molecules and fragments to be desorbed from the surface of the sample. Spectroscopic analysis of the fluoresced x-rays provides quantitative trace element information of the sample volume probed by the beam. The elemental data are subsequently used to identify peaks in the mass analysis of the desorbed species, thereby providing a detailed description of the local surface chemistry. High-resolution (micron-scale) chemical imaging is possible by scanning the beam over the sample.

Morse, D H; Grant, P G; Antolak, A J; Sproch, N; Fernando, Q

2002-05-31

24

Eddy covariance emission and deposition flux measurements using proton transfer reaction-time of flight-mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes  

NASA Astrophysics Data System (ADS)

During summer 2010, a proton transfer reaction-time of flight-mass spectrometer (PTR-TOF-MS) and a standard proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m ? m-1) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e. co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 ?g C m-2 h-1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 ?g C m-2 h-1) and methanol (m/z 33.032, 18%, 72 ?g C m-2 h-1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 ?g C m-2 h-1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 ?g C m-2 h-1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 ?g C m-2 h-1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 ?g C m-2 h-1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 ?g C m-2 h-1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 ?g C m-2 h-1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

Park, J.-H.; Goldstein, A. H.; Timkovsky, J.; Fares, S.; Weber, R.; Karlik, J.; Holzinger, R.

2012-08-01

25

Eddy covariance emission and deposition flux measurements using proton transfer reaction - time of flight - mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes  

NASA Astrophysics Data System (ADS)

During summer 2010, a proton transfer reaction - time of flight - mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/?m) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 ?g C m-2 h-1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 ?g C m-2 h-1) and methanol (m/z 33.032, 18%, 72 ?g C m-2 h-1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 ?g C m-2 h-1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 ?g C m-2 h-1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 ?g C m-2 h-1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 ?g C m-2 h-1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 ?g C m-2 h-1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 ?g C m-2 h-1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

Park, J.-H.; Goldstein, A. H.; Timkovsky, J.; Fares, S.; Weber, R.; Karlik, J.; Holzinger, R.

2013-02-01

26

Screening analysis for medicinal drugs and drugs of abuse in whole blood using ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS)--toxicological findings in cases of alleged sexual assault.  

PubMed

An ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) method for simultaneous screening of 46 medicinal drugs and drugs of abuse in whole blood was developed and validated. The method includes most of the commonly used and abused drugs such as amphetamines, cocaine, benzodiazepines, and opioids. Chromatographic separation of the targeted drugs was achieved using a Waters ACQUITY UPLC coupled to a Waters Micromass LCT Premier XE time-of-flight mass spectrometer. The total chromatographic run time was 13.5 min injection to injection. The estimated method LOQ is in the range of 0.06-27 ng/g, which is below the therapeutic levels for each of the drugs analyzed but LSD. The extraction recovery ranged from 6% to 197% with median value 95% and mean value 82%. Matrix effect ranged from 81% suppression to 29% enhancement of the signals compared to signals obtained in the absence of biological matrix. The method was tested on 55 authentic forensic toxicology samples confirming the same positive results as found using the routine analytical procedures as well as some additional compounds. Recently there has been considerable attention paid to drug-facilitated sexual assault and the toxicological findings in these cases. As part of a pilot study to investigate the prevalence of medicinal drugs, drugs of abuse, and alcohol in victims of alleged sexual assault, biological specimens were obtained from 167 victims being examined at the Sexual Assault Center in Aarhus, Denmark. The obtained blood samples were analyzed using the novel screening method supported by additional analyses for e.g. THC and alcohol. 124 victims reported they have been drinking alcohol prior to the assault (74%). Alcohol analyses revealed 59 positive findings (48%). 35 of the cases were found positive for one or more drugs excluding alcohol (21%). 20 of the victims reported they have been subject to a drug-facilitated sexual assault (12%). For the victims suspecting drug-facilitated sexual assault, the toxicological analyses revealed four positive for alcohol and nine victims were positive for one or more drugs, with six of the victims found positive for benzodiazepines or other drugs with sedative effects. It was notable that victims tested positive for medicinal drugs and drugs of abuse as well as victims of alleged drug-facilitated sexual assault in average underwent medical examination later than the whole study population. PMID:22770621

Birkler, Rune Isak Dupont; Telving, Rasmus; Ingemann-Hansen, Ole; Charles, Annie Vesterby; Johannsen, Mogens; Andreasen, Mette Findal

2012-07-06

27

Separation efficiency of a chemical warfare agent simulant in an atmospheric pressure ion mobility time-of-flight mass spectrometer (IM(tof)MS)  

Microsoft Academic Search

An electrospray ionization atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer (IM(tof)MS) that routinely achieves mobility and mass separation efficiencies in line with theoretical limits is reported. The maximum IM(tof)MS efficiency for a given instrumental design depends widely upon the various key parameters such as voltage, temperature, initial pulse width, interface and reflectron energies. Optimization of the current IM(tof)MS

Wes E. Steiner; William A. English; Herbert H. Hill

2005-01-01

28

Genetic and Ecological Correlates of Intraspecific Variation in Pitviper Venom Composition Detected Using Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) and Isoelectric Focusing  

Microsoft Academic Search

The ability to detect biochemical diversity in animal venoms has wide-ranging implications for a diverse array of scientific disciplines. Matrix-assisted laser desorption time-of-flight mass spectrometry (and, for comparative purposes, isoelectric focusing) were used to characterize venoms from a geographically diverse sample of Trimeresurus stejnegeri (n 2 isoforms (PLA2) and in whole venom profiles. Geographic variation in venom was primarily between

Simon Creer; Anita Malhotra; Roger S. Thorpe; Reto S. Stöcklin; Philippe S. Favreau; Wen S. Hao Chou

2003-01-01

29

Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in preparation of chitosan oligosaccharides (COS) with degree of polymerization (DP) 5-12 containing well-distributed acetyl groups  

NASA Astrophysics Data System (ADS)

COS have many biological activities, and have been widely used as a health food. Molecular size is considered as a key parameter for COS' activities. However, many criteria are used practically, and true qualities of COS from different producers may not be always comparable. This can partly explain the disagreement in COS' functional researches, as resulting in COS, even with astonish effects, have not been further developed as a drug for tumor patients. As anti-tumor activities have been studied based on DP in pharmacological researches, we employed MALDI-TOF-MS to monitor fine structure, including DP, in COS' preparation and comparison. Then one of the COS products was analyzed with the composition of DP 5-12, mainly 7-10. Moreover, that COS' product contains well-distributed acetyl groups, while typical Commercial COS sample nearly contains no acetyl groups. As fresh precise parameters, the DP and the number of acetyl groups matching with special DP can be introduced in COS' further study on structure-activity relationships (SARs) as a new drug.

Chen, Mian; Zhu, Xiqiang; Li, Zhiming; Guo, Xueping; Ling, Peixue

2010-02-01

30

Effect of metformin on the urinary metabolites of diet-induced-obese mice studied by ultra performance liquid chromatography coupled to time-of-flight mass spectrometry (UPLC-TOF/MS).  

PubMed

Obesity is becoming a health concern worldwide and metformin, a first line anti-diabetic drug, was associated with weight loss under different backgrounds. However, most researches focused on the anti-diabetic mechanism and less attention has been paid on the mechanism of weight loss of metformin. Therefore, we established a metabonomic method to evaluate metformin action in preventing obesity in a high fat diet-induced-obesity (DIO) mice model. 36 male C57BL/6 mice (8-week old) were randomly divided into control group (n=12, normal chow), model group (n=12, high fat chow) and metformin group (n=12, high fat chow and dosed with metformin) over 16 weeks. A urinary metabonomic study using UPLC-TOF/MS was performed in combination with multivariate statistical analysis. In addition, indices of body weight and food intake as well as fasting blood glucose, fed blood glucose, oral glucose tolerance test (OGTT) and plasma insulin were collected. Significant weight loss in metformin-treated mice was achieved and 21 potential biomarkers were identified. Decreased glucose, myristic acid, stearidonic acid, lysoPC (16:0), lysoPC (18:0), L-glutamic acid, L-methionine, L-threonine, L-phenylalanine, L-histidine, L-carnitine, L-malic acid and pantothenic acid in urine indicated that metformin may have exerted effects on energy metabolism. Further, based on the biomarkers, we cautiously propose that tricarboxylic acid cycle (TCA) may have been compromised by metformin and might contribute to the activation of adenosine monophosphate kinase (AMPK), then AMPK activation led to more ?-oxidation of certain fatty acids and augmented lipolysis and thus induced weight loss. Related cellular and molecular studies are being considered to further investigate the underlying mechanism. PMID:23523884

Zhu, Yunyun; Feng, Yi; Shen, Lan; Xu, Desheng; Wang, Bin; Ruan, Kefeng; Cong, Wenjuan

2013-03-08

31

The SELDI-TOF MS Approach to Proteomics: Protein Profiling and Biomarker Identification  

Microsoft Academic Search

The need for methods to identify disease biomarkers is underscored by the survival-rate of patients diagnosed at early stages of cancer progression. Surface enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is a novel approach to biomarker discovery that combines two powerful techniques: chromatography and mass spectrometry. One of the key features of SELDI-TOF MS is its ability to provide

Haleem J. Issaq; Timothy D. Veenstra; Thomas P. Conrads; Donna Felschow

2002-01-01

32

Investigating the human metabolism of acetaminophen using UPLC and exact mass oa-TOF MS  

Microsoft Academic Search

The ability to rapidly detect and characterize drug metabolites in biological fluids often relies on a combination of a high quality chromatographic separation and sensitive high resolution mass spectrometry. Here, the performance of two high throughput LC\\/MS approaches, namely monolith columns and sub-2?m particle Ultra Performance Liquid Chromatography (UPLC) columns is compared for the detection and identification of the human

Kelly A. Johnson; Robert Plumb

2005-01-01

33

On the possible in situ elemental analysis of small bodies with laser ablation TOF-MS  

Microsoft Academic Search

An analysis is presented of the potential application of laser ablation time-of-flight mass spectrometry (LA-TOF-MS) to the study of small bodies on in situ and sample return missions. LA-TOF-MS provides the significant advantages of high-quality, low-ambiguity data, no requirement of sample contact or preparation, rapid analysis, and local probe capability. The ability to address particular scientific goals on a given

W. B. Brinckerhoff

2005-01-01

34

Investigation of pesticide metabolites in food and water by LC-TOF-MS  

Microsoft Academic Search

We illustrate the potential of liquid chromatography with (quadrupole) time-of-flight mass spectrometry [LC-(Q)TOF-MS] in investigating the presence of pesticide metabolites in food and water samples. The higher polarity of metabolites compared to their parent pesticides makes the combination of LC [both high-performance (HPLC) and ultra-performance (UPLC)] with TOF-MS one of the most appropriate techniques for their analysis, mainly from a

F. Hernández; J. V. Sancho; M. Ibáñez; S. Grimalt

2008-01-01

35

An automated GCxGC-TOF-MS protocol for batch-wise extraction and alignment of mass isotopomer matrixes from differential 13C-labelling experiments: a case study for photoautotrophic-mixotrophic grown Chlamydomonas reinhardtii cells.  

PubMed

Two dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOF-MS) is a promising technique to overcome limits of complex metabolome analysis using one dimensional GC-TOF-MS. Especially at the stage of data export and data mining, however, convenient procedures to cope with the complexity of GCxGC-TOF-MS data are still in development. Here, we present a high sample throughput protocol exploiting first and second retention index for spectral library search and subsequent construction of a high dimensional data matrix useful for statistical analysis. The method was applied to the analysis of (13)C-labelling experiments in the unicellular green alga Chlamydomonas reinhardtii. We developed a rapid sampling and extraction procedure for Chlamydomonas reinhardtii laboratory strain (CC503), a cell wall deficient mutant. By testing all published quenching protocols we observed dramatic metabolite leakage rates for certain metabolites. To circumvent metabolite leakage, samples were directly quenched and analyzed without separation of the medium. The growth medium was adapted to this rapid sampling protocol to avoid interference with GCxGC-TOF-MS analysis. To analyse batches of samples a new software tool, MetMax, was implemented which extracts the isotopomer matrix from stable isotope labelling experiments together with the first and second retention index (RI1 and RI2). To exploit RI1 and RI2 for metabolite identification we used the Golm metabolome database (GMD [1] with RI1/RI2-reference spectra and new search algorithms. Using those techniques we analysed the dynamics of (13)CO(2) and (13)C-acetate uptake in Chlamydomonas reinhardtii cells in two different steady states namely photoautotroph and mixotroph growth conditions. PMID:19206143

Kempa, Stefan; Hummel, Jan; Schwemmer, Thorsten; Pietzke, Matthias; Strehmel, Nadine; Wienkoop, Stefanie; Kopka, Joachim; Weckwerth, Wolfram

2009-02-01

36

MALDI-TOF MS in Prenatal Genomics  

PubMed Central

Summary Prenatal diagnosis aims either to provide the reassurance to the couples at risk of having an affected child by timely appropriate therapy or to give the parents a chance to decide the fate of the unborn babies with health problems. Invasive prenatal diagnosis (IPD) is accurate, however, carrying a risk of miscarriage. Non-invasive prenatal diagnosis (NIPD) has been developed based on the existing of fetal genetic materials in maternal circulation; however, a minority fetal DNA in majority maternal background DNA hinders the detections of fetal traits. Different protocols and assays, such as homogenous MassEXTEND (hME), single allele base extension reaction (SABER), precise measuring copy number variation of each allele, and quantitative methylation and expression analysis using the high-throughput sensitive matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), allow NIPD for single gene disorders, fetal blood group genotyping and fetal aneuploidies as well as the development of fetal gender-independent biomarkers in maternal circulation for management of pathological pregnancies. In this review, we summarise the use of MALDI-TOF MS in prenatal genomics.

Zhong, Xiao Yan; Holzgreve, Wolfgang

2009-01-01

37

Construction and application of a mass spectral and retention time index database generated from plant GC\\/EI-TOF-MS metabolite profiles  

Microsoft Academic Search

The non-supervised construction of a mass spectral and retention time index data base (MS\\/RI library) from a set of plant metabolic profiles covering major organs of potato (Solanum tuberosum), tobacco (Nicotiana tabaccum), and Arabidopsis thaliana, was demonstrated. Typically 300–500 mass spectral components with a signal to noise ratio ?75 were obtained from GC\\/EI-time-of-flight (TOF)-MS metabolite profiles of methoxyaminated and trimethylsilylated

Cornelia Wagner; Michael Sefkow; Joachim Kopka

2003-01-01

38

The mass spectral density in quantitative time-of-flight mass spectrometry of polymers  

Microsoft Academic Search

Time-of-flight mass spectrometry (TOF-MS) is being increasingly used for the study of polymers, for example to obtain the distribution of molecular masses for polymer samples. Serious efforts have also been underway to use TOF-MS for DNA sequencing. In TOF-MS the data is obtained in the form of a time-series that represents the distribution in arrival times of ions of various

Ranjeet S. Tate; Dan Ebeling; Lloyd M. Smith

2001-01-01

39

Quantitative matrix-assisted laser desorption/ionization mass spectrometry  

PubMed Central

This review summarizes the essential characteristics of matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS), especially as they relate to its applications in quantitative analysis. Approaches to quantification by MALDI-TOF MS are presented and published applications are critically reviewed.

Roder, Heinrich; Hunsucker, Stephen W.

2008-01-01

40

Improved mass accuracy in PTR-TOF-MS: Another step towards better compound identification in PTR-MS  

Microsoft Academic Search

Proton transfer reaction mass spectrometry (PTR-MS) provides on-line monitoring of volatile organic compounds (VOCs) with a low detection threshold and a fast response time. Commercially available set-ups are usually based on quadrupole analysers that, due to the unit mass resolution, do not provide useful analytical information besides the nominal mass of the ions detected. Recently new instruments based on time-of-flight

Luca Cappellin; Franco Biasioli; Alessandra Fabris; Erna Schuhfried; Christos Soukoulis; Tilmann D. Märk; Flavia Gasperi

2010-01-01

41

Mass spectrometry with cryogenic detectors  

NASA Astrophysics Data System (ADS)

Cryogenic detectors have recently been applied for the first time as ion detectors in time-of-flight mass spectrometry (TOF-MS). Because of their energy sensitivity cryogenic detectors are expected to have near 100% efficiency even for very large, slow-moving molecules, in contrast to microchannel plates whose efficiency drops considerably at large mass. Thus, cryogenic detectors could contribute to extending the mass range accessible by TOF-MS and help improving detection limits. In addition, the energy resolution provided by cryogenic detectors can be used for charge discrimination and studies of ion fragmentation, ion-detector interaction, and internal energies of large molecular ions. Cryogenic detectors could therefore prove to be a valuable diagnostic tool in TOF-MS. Here I summarize the results of recent demonstration experiments.

Frank, M.

2000-04-01

42

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry in clinical chemistry  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-Tof-MS) has recently become a popular and versatile method to analyze macromolecules from biological origin. In this paper, we will review the application of MALDI-Tof-MS in clinical chemistry and biology. MALDI-Tof-MS is used in clinical chemistry, e.g. disease markers can be identified with MALDI-MS analysis in combination with 1-D and 2-D gel electrophoresis separations

Laure F. Marvin; Matthew A. Roberts; Laurent B. Fay

2003-01-01

43

MALDI-TOF MS sample preparation by using alkanethiolate self-assembled monolayers  

NASA Astrophysics Data System (ADS)

Samples originating from body fluids often contain a complex mixture of inorganic salts, buffers, chaotropic agents, surfactant/detergents, preservatives, and other solubilizing agents. The presence of those contaminants often precludes direct analysis by matrix-assisted laser-desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Self-assembled monolayers (SAMs) on coinage metal can provide versatile modeling systems for studies of interfacial electron transfer, biological interactions, molecular recognition and other interfacial phenomena. In this study, SAMs surface was used for MALDI-TOF MS sample cleanup application. Experimental results from MALDI-TOF MS have revealed the better S/N ratio and resolution of using functionalized SAMs surface for the demonstration of bovine serum albumin (BSA) in artificial human urine sample. This paper reports a surface modification and cleanup method that greatly simplifies this sample preparation process.

Tyan, Yu-Chang; Yang, Ming-Hui; Liao, Pao-Chi; Liao, Jiunn-Der; Jong, Shiang-Bin; Liu, Chia-Yuan; Wang, Ming-Chen; Grunze, Michael

2007-04-01

44

A high resolution and high sensitivity proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS)  

Microsoft Academic Search

Proton-transfer-reaction mass spectrometry (PTR-MS) developed about 10 years ago is used today in a wide range of scientific and technical fields allowing real-time on-line measurements of volatile organic compounds in air with a high sensitivity and a fast response time. Most instruments employed so far use quadrupole filters to analyze product ions generated in the reaction drift tube. Due to

A. Jordan; S. Haidacher; G. Hanel; E. Hartungen; L. Märk; H. Seehauser; R. Schottkowsky; P. Sulzer; T. D. Märk

2009-01-01

45

Protein quantification by the SELDI-TOF-MS–based ProteinChip® System  

Microsoft Academic Search

Surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) represents the successful combination of retentate chromatography and mass spectrometry, and this technology is an integral part of Ciphergen's ProteinChip System, which was designed to answer biomedical questions by performing protein analyses on a single experimental platform. The quantification capability of the ProteinChip System is essential in all proteomic applications for which this

Sonja Vorderwülbecke; Steve Cleverley; Scot R Weinberger; Andreas Wiesner

2005-01-01

46

Tropical Greenhouse Measurements of Volatile Organic Compounds Using Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectromety (PTR-TOF-MS)  

NASA Astrophysics Data System (ADS)

In this presentation, we will summarize the results of measurements made in an approximately 1300 m3 tropical greenhouse at the Johannes Gutenberg University botanical garden in Mainz Germany conducted over a one month period. The greenhouse is home to a large variety of plant species from hot and humid regions of the world. The greenhouse is also host to several crops such as Cocoa and Cola Nut as well as ornamental plants. A particular focus of the species maintained are those which are considered ant plants, or plants which have an intimate relationship with ants in tropical habitats. Volatile organic compounds (VOCs) were measured using a Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) using H3O+, NO+, and O2+ ion chemistry. Measurements will be presented both for primary emissions observed in the closed greenhouse atmosphere as well as the oxidation products observed after the introduction of ambient ozone. The high resolving power (5000 m/?m) of the time-of-flight instrument allows for the separation of isobaric species. In particular, both isoprene (68.1170 amu) and furan (68.0740 amu) were observed and separated as primary emissions during this study. The significance of this will be discussed in terms of both atmospheric implications as well as with respect to previous measurements of isoprene obtained using quadrupole PTR-MS where isobaric separation of these compounds is not possible. Additionally observed species (e.g. Methanol, Acetaldehyde, MVK and MEK) will be discussed in detail with respect to their behavior as a function of light, temperature and relative humidity. The overall instrument performance of the PTR-TOF-MS technique using the H3O+, NO+, and O2+ primary ions for the measurement of VOCs will be evaluated.

Veres, P.; Auld, J.; Williams, J.

2012-04-01

47

Top-down proteomic identification of protein biomarkers of food-borne pathogens using MALDI-TOF-TOF-MS/MS  

Technology Transfer Automated Retrieval System (TEKTRAN)

This chapter describes a step-by-step protocol and discussion of top-down proteomic identification of protein biomarkers of food-borne pathogens using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-TOF-MS/MS) and web-based software developed in the Pro...

48

MALDI-TOF MS in microbiological diagnostics-identification of microorganisms and beyond (mini review).  

PubMed

Few developments in microbiological diagnostics have had such a rapid impact on species level identification of microorganisms as matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Conventional differentiation methods rely on biochemical criteria and require additional pre-testing and lengthy incubation procedures. In comparison, MALDI-TOF MS can identify bacteria and yeast within minutes directly from colonies grown on culture plates. This radically new, methodically simple approach profoundly reduces the cost of consumables and time spent on diagnostics. The reliability and accuracy of the method have been demonstrated in numerous studies and different systems are already commercially available. Novel applications of the system besides microbial species level identification are also being explored. This includes identification of pathogens from positive blood cultures or directly from patient samples, such as urine. Currently, intriguing MALDI-TOF MS developments are being made regarding the phenotypic detection of certain antibiotic resistance mechanisms, e.g., ?-lactamases and carbapenemases. This mini review provides an overview of the literature in the field and also includes our own data and experiences gathered from over 4 years of routine MALDI-TOF MS use in a university hospital's microbiological diagnostics facility. PMID:22198716

Wieser, Andreas; Schneider, Lukas; Jung, Jette; Schubert, Sören

2011-12-25

49

A MALDI-TOF MS procedure for clinical dermatophyte species identification in the routine laboratory.  

PubMed

Abstract The conventional identification of dermatophytes requires a long turnaround time and highly skilled mycologists. We have recently developed a standardized matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) assay to routinely identify molds of potential clinical significance. This study objective was to determine if this same assay could also be employed to identify clinical dermatophytes in the routine laboratory setting. The effects of the inclusion of cycloheximide in the culture medium and incubation time were tested after building a reference spectra library that included 48 well-characterized isolates of 17 dermatophyte species. Then these same isolates were prospectively identified using this library. MALDI-TOF MS-based identification was effective regardless of the presence of cycloheximide or incubation time as 130/133 (97.8%) of the clinical isolates were appropriately identified. Two Microsporum canis isolates yielded uninformative spectra and one M. audouinii isolate was misidentified. Since one only requires a small colony for MALDI-TOF MS analysis, accurate identifications were obtained in 3-6 days and, specifically, before the appearance of their characteristic morphological features. Consequently, identification turnaround time was dramatically reduced as compared to that needed for conventional morphological identification. In conclusion, this standardized MALDI-TOF MS-based identification procedure for filamentous fungi effectively identifies clinical dermatophyte isolates and drastically reduces the response times in the routine clinical laboratory. PMID:23611419

L'ollivier, Coralie; Cassagne, Carole; Normand, Anne-Cecile; Bouchara, Jean-Philippe; Contet-Audonneau, Nelly; Hendrickx, Marijke; Fourquet, Patrick; Coulibaly, Oumar; Piarroux, Renaud; Ranque, Stephane

2013-04-23

50

MALDI-TOF MS Distinctly Differentiates Nontypable Haemophilus influenzae from Haemophilus haemolyticus  

PubMed Central

Nontypable Haemophilus influenzae (NTHi) and Haemophilus haemolyticus exhibit different pathogenicities, but to date, there remains no definitive and reliable strategy for differentiating these strains. In this study, we evaluated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as a potential method for differentiating NTHi and H. haemolyticus. The phylogenetic analysis of concatenated 16S rRNA and recombinase A (recA) gene sequences, outer membrane protein P6 gene sequencing and single-gene PCR were used as reference methods. The original reference database (ORD, provided with the Biotyper software) and new reference database (NRD, extended with Chinese strains) were compared for the evaluation of MALDI-TOF MS. Through a search of the ORD, 76.9% of the NTHi (40/52) and none of the H. haemolyticus (0/20) strains were identified at the species level. However, all NTHi and H. haemolyticus strains used for identification were accurately recognized at the species level when searching the NRD. From the dendrogram clustering of the main spectra projections, the Chinese and foreign H. influenzae reference strains were categorized into two distinct groups, and H. influenzae and H. haemolyticus were also separated into two categories. Compared to the existing methods, MALDI-TOF MS has the advantage of integrating high throughput, accuracy and speed. In conclusion, MALDI-TOF MS is an excellent method for differentiating NTHi and H. haemolyticus. This method can be recommended for use in appropriately equipped laboratories.

Zhang, Huifang; Zhang, Yongchan; Gao, Yuan; Xu, Li; Lv, Jing; Wang, Yingtong; Zhang, Jianzhong; Shao, Zhujun

2013-01-01

51

Improved ionization sources and detection methods for analytical mass spectrometry  

SciTech Connect

A new time-of-flight mass spectrometer (TOF-MS) has been developed for direct characterization of solid samples and fundamental studies. A N{sub 2} laser ({lambda} = 337 nm) was used with the linear TOF-MS to study ion formation from various solid specimens. Improved techniques were incorporated for fast ion detection and data acquisition. For inorganic specimens the mass resolution was {approximately} 2000 at m/z = 400, a considerable improvement over earlier reports for instruments using a linear ion optical path. The TOF-MS was designed specifically to permit investigation of the information available from the individual TOF scans. The approach is described and results are given for the LD-TOF-MS spectra of CsI and a superconducting sample, YBa{sub 2}Cu{sub 3}O{sub 7}. Other improvements in laser excitation of specimens and detection methods for analytical mass spectrometry are also described.

Huang, L.Q.

1987-01-01

52

Characterization of complex hydrocarbons in cigarette smoke condensate by gas chromatography–mass spectrometry and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry  

Microsoft Academic Search

Gas chromatography–mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to

Xin Lu; Mingyue Zhao; Hongwei Kong; Junlan Cai; Jianfang Wu; Ming Wu; Ruixiang Hua; Jianfu Liu; Guowang Xu

2004-01-01

53

Efficient Analysis of Non-Polar Environmental Contaminants by MALDI-TOF MS with Graphene as Matrix  

Microsoft Academic Search

In this Application Note, we describe, for the first time, the rapid analysis of hydrophobic compounds present in environmental\\u000a contaminants, which includes polycyclic aromatic hydrocarbons (PAHs) and estrogen, by matrix-assisted laser desorption\\/ionization\\u000a time-of-flight mass spectrometry (MALDI-TOF MS) with the use of graphene as matrix. MALDI-TOF MS with conventional matrix\\u000a has limitations in analyzing low-polarity compounds owing to their difficulty in

Jing Zhang; Xiaoli Dong; Jinsheng Cheng; Jinghong Li; Yinsheng Wang

2011-01-01

54

A Plant Peptide Encoded by CLV3 Identified by in Situ MALDI-TOF MS Analysis  

Microsoft Academic Search

The Arabidopsis CLAVATA3 (CLV3) gene encodes a stem cell-specific protein presumed to be a precursor of a secreted peptide hormone. Matrix-assisted laser desorption\\/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) applied to in situ Arabidopsis tissues determined the structure of a modified 12-amino acid peptide (MCLV3), which was derived from a conserved motif in the CLV3 sequence. Synthetic MCLV3 induced shoot and root

Tatsuhiko Kondo; Shinichiro Sawa; Atsuko Kinoshita; Satoko Mizuno; Tatsuo Kakimoto; Hiroo Fukuda; Youji Sakagami

2006-01-01

55

Optimization of MALDI-TOF MS for strain level differentiation of Arthrobacter isolates  

Microsoft Academic Search

Matrix-assisted laser-desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been shown to be a rapid and sensitive method for characterization of bacteria, but it has not yet become a routine microbiological procedure. Currently there are no standardized protocols that would allow development of large libraries of reproducible protein profiles from a broad range of microorganisms to use for identification purposes. Important

Márta Vargha; Zoltán Takáts; Allan Konopka; Cindy H. Nakatsu

2006-01-01

56

Using oxidized carbon nanotubes as matrix for analysis of small molecules by MALDI-TOF MS  

Microsoft Academic Search

Oxidized carbon nanotubes are tested as a matrix for analysis of small molecules by matrix assisted laser desorption\\/ionization\\u000a time of flight mass spectrometry (MALDI-TOF-MS). Compared with nonoxidized carbon nanotubes, oxidized carbon nanotubes facilitate\\u000a sample preparation because of their higher solubility in water. The matrix layer of oxidized carbon nanotubes is much more\\u000a homogeneous and compact than that of nonoxidized carbon

Chensong Pan; Songyun Xu; Ligang Hu; Xingye Su; Junjie Ou; Hanfa Zou; Zhong Guo; Yu Zhang; Baochuan Guo

2005-01-01

57

SELDI-TOF-MS of saliva: Methodology and pre-treatment effects  

Microsoft Academic Search

Interest in saliva as a diagnostic fluid for monitoring general health and for early diagnosis of disease has increased in the last few years. In particular, efforts have focused on the generation of protein maps of saliva using advanced proteomics technology. Surface-enhanced laser-desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is a novel high throughput and extremely sensitive proteomic approach that allows protein

Raymond Schipper; Arnoud Loof; Jolan de Groot; Lucien Harthoorn; Eric Dransfield; Waander van Heerde

2007-01-01

58

A novel strategy for MALDI-TOF MS analysis of small molecules  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) does not work efficiently on small\\u000a molecules (usually with molecular weight below 500 Da) because of the interference of matrix-related peaks in low m\\/z region. The previous methods developed for this problem focused on reducing the peaks caused by the traditional matrices.\\u000a Here, we report a novel strategy to analyze small molecules

Shu Zhang; Jian’an Liu; Yi Chen; Shaoxiang Xiong; Guanghui Wang; Jun Chen; Guoqiang Yang

2010-01-01

59

Characterization of coal-derived materials by laser desorption mass spectrometry.  

National Technical Information Service (NTIS)

Laser desorption time-of-flight mass spectrometry (LD/TOF MS) is used to characterize complex mixtures of large molecules derived from coals and separated coal macerals. Three groups of macerals, namely liptinite, vitrinite, and inertinite from Argonne Pr...

J. E. Hunt K. R. Lykke R. E. Winans

1991-01-01

60

Mass spectrometry and tandem mass spectrometry characterization of protein patterns, protein markers and whole proteomes for pathogenic bacteria.  

PubMed

There have been many recent reviews published on MALDI-TOF MS (matrix assisted laser desorption/ionization time-of-flight) MS (mass spectrometry) for identification of bacteria particularly with relevance to clinical microbiology. MALDI-TOF MS is now a mature technique for bacterial identification with great promise. The purpose of this review is to put into perspective MALDI-TOF MS and other widely used mass spectrometry methods for characterization of proteins. MALDI-TOF MS is used for rapid determination of a mass pattern of proteins for bacterial characterization; these proteins are generally not identified. Alternatively after gel separation, MALDI-TOF-TOF MS-MS (tandem mass spectrometry) or on-line LC-ESI MS-MS (liquid chromatography-electrospray tandem mass spectrometry) specific protein markers can be identified and peptide sequence variation among species assessed. Unlike direct MALDI-TOF MS, sample preparation for gel separation/MALDI-TOF-TOF MS and MS-MS remains quite demanding. Specific marker proteins are readily identified. Sample preparation is quite straight-forward for LC-MS-MS. Massive amounts of information (whole proteomes) are provided but bioinformatics is complex. Chromatography and electrospray mass spectrometry instrumentation is also not widely used among microbiologists. Thus, there is a need for further development in sample preparation and instrumental development for rapid and simplified analysis. As MS-MS for microbial characterization reaches maturity, it is to be anticipated that further developments in bioinformatics will also become essential. The genome codes for all proteins that might be synthesized under certain growth conditions but only direct protein identification can prove that specific proteins or networks of proteins are actually expressed which might be of relevance in improving our understanding of bacterial pathogenesis. PMID:23318550

Intelicato-Young, Jennifer; Fox, Alvin

2013-01-12

61

Reliable identification at the species level of Brucella isolates with MALDI-TOF-MS  

PubMed Central

Background The genus Brucella contains highly infectious species that are classified as biological threat agents. The timely detection and identification of the microorganism involved is essential for an effective response not only to biological warfare attacks but also to natural outbreaks. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is a rapid method for the analysis of biological samples. The advantages of this method, compared to conventional techniques, are rapidity, cost-effectiveness, accuracy and suitability for the high-throughput identification of bacteria. Discrepancies between taxonomy and genetic relatedness on the species and biovar level complicate the development of detection and identification assays. Results In this study, the accurate identification of Brucella species using MALDI-TOF-MS was achieved by constructing a Brucella reference library based on multilocus variable-number tandem repeat analysis (MLVA) data. By comparing MS-spectra from Brucella species against a custom-made MALDI-TOF-MS reference library, MALDI-TOF-MS could be used as a rapid identification method for Brucella species. In this way, 99.3% of the 152 isolates tested were identified at the species level, and B. suis biovar 1 and 2 were identified at the level of their biovar. This result demonstrates that for Brucella, even minimal genomic differences between these serovars translate to specific proteomic differences. Conclusions MALDI-TOF-MS can be developed into a fast and reliable identification method for genetically highly related species when potential taxonomic and genetic inconsistencies are taken into consideration during the generation of the reference library.

2011-01-01

62

The potential of combining ion trap/MS/MS and TOF/MS for identification of emerging contaminants  

USGS Publications Warehouse

The use of a method combining ion trap tandem mass spectrometry (MS/MS) and time of flight mass spectrometry (TOF/MS) for identification of emerging contaminates was discussed. The two tools together complemented each other in sensitivity, fragmentation and accurate mass determination. Liquid chromatography/electrospray ionization/ion-trap tandem mass spectrometry (LC/ESI/MS/MS), in positive ion mode of operation, was used to separate and identify specific compounds. Diagnostic fragment ions were obtained for a polyethyleneglycol(PEG) homolog by ion trap MS/MS, and fragments were measured by TOF/MS. It was observed that the combined method gave an exact mass measurement that differed from the calculated mass.

Ferrer, I.; Furlong, E. T.; Heine, C. E.; Thurman, E. M.

2002-01-01

63

Advances in Identification of Clinical Yeast Isolates by Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based identification is being adopted by clinical laboratories for routine identification of microorganisms. To date, the majority of studies have focused on the performance and optimization of MALDI-TOF MS for the identification of bacterial isolates. We review recent literature describing the use of MALDI-TOF MS for the routine identification of a variety of yeasts and yeast-like isolates. Specific topics include the effect of optimized or streamlined extraction methods, modified scoring thresholds, expanded reference libraries, and the possibility of conducting antifungal susceptibility testing using MALDI-TOF MS.

Buchan, Blake W.

2013-01-01

64

On the possible in situ elemental analysis of small bodies with laser ablation TOF-MS  

NASA Astrophysics Data System (ADS)

An analysis is presented of the potential application of laser ablation time-of-flight mass spectrometry (LA-TOF-MS) to the study of small bodies on in situ and sample return missions. LA-TOF-MS provides the significant advantages of high-quality, low-ambiguity data, no requirement of sample contact or preparation, rapid analysis, and local probe capability. The ability to address particular scientific goals on a given mission depends strongly on obtaining reproducible instrument- and sample-dependent fractionation factors for heterogeneous samples in various operating conditions. LA-TOF-MS analyses of basalt and mineral separate standards, in both powdered and compressed forms, have been used to establish an understanding of elemental fractionation in the mass range from C to Zn and selected higher-mass elements. Results of a preliminary calibration applied to the bulk analysis of carbonaceous meteorites suggests that sufficient precision is obtained from replicate averaging of spectra to differentiate among some sub-classes. Complementary point-by-point LA analyses of such samples could also provide powerful diagnostic information for mineralogy.

Brinckerhoff, W. B.

2005-07-01

65

Identification of Orcokinin Gene-Related Peptides in the Brain of the Crayfish Procambarus clarkii by the Combination of MALDI-TOF and On-Line Capillary HPLC\\/Q-Tof Mass Spectrometries and Molecular Cloning  

Microsoft Academic Search

We developed a strategy for the exploration of brain peptides in the red swamp crayfish, Procambarus clarkii, utilizing the combined techniques of matrix-assisted laser desorption\\/ionization with time-of-flight mass spectrometry (MALDI-TOF MS), molecular cloning, and on-line capillary reversed-phase HPLC\\/quadrupole orthogonal acceleration time-of-flight (Q-Tof)-MS. We initially performed direct MALDI-TOF MS analysis with slices of the brain. The MS spectra from a slice

Yoshimi Yasuda-Kamatani; Akikazu Yasuda

2000-01-01

66

Identification and quantitation of pesticides in vegetables by liquid chromatography time-of-flight mass spectrometry  

Microsoft Academic Search

This overview covers pesticide-residue determination in food samples by liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS). We present the application of LC-TOF-MS in terms of accuracy, sensitivity and robustness for the quantitative analysis of pesticides in fruit and vegetable samples. The analytical performance of the methodology is validated for various types of vegetables matrices.Accurate mass measurements (with accuracy better than 3ppm

Imma Ferrer; Juan Francisco García-Reyes; Amadeo Fernandez-Alba

2005-01-01

67

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry in clinical chemistry  

Microsoft Academic Search

Abstract Matrix-assisted laser desorption\\/ionization time-of-flight mass,spectrometry,(MALDI-Tof-MS) has recently become,a popular and versatile method to analyze macromolecules from biological origin. In this paper, we will review the application of MALDI-Tof-MS in clinical chemistry and biology. MALDI-Tof-MS is used in clinical chemistry, e.g. disease markers can be identified with MALDI-MS analysis in combination,with 1-D and 2-D gel electrophoresis separations thanks to either

Laure F. Marvin; Matthew A. Roberts; Laurent B. Fay

68

Top-down proteomic identification of bacterial protein biomarkers and toxins using MALDI-TOF-TOF-MS/MS and post-source decay  

Technology Transfer Automated Retrieval System (TEKTRAN)

Matrix-assisted laser desorption/ionization time-of-flight-time-of-flight mass spectrometry(MALDI-TOF-TOF-MS)has provided new capabilities for the rapid identification of digested and non-digested proteins. The tandem (MS/MS) capability of TOF-TOF instruments allows precursor ion selection/isolation...

69

Gold patterned biochips for on-chip immuno-MALDI-TOF MS: SPR imaging coupled multi-protein MS analysis.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of immuno-captured target protein efficiently complements conventional immunoassays by offering rich molecular information such as protein isoforms or modifications. Direct immobilization of antibodies on MALDI solid support enables both target enrichment and MS analysis on the same plate, allowing simplified and potentially multiplexing protein MS analysis. Reliable on-chip immuno-MALDI-TOF MS for multiple biomarkers requires successful adaptation of antibody array biochips, which also must accommodate consistent reaction conditions on antibody arrays during immuno-capture and MS analysis. Here we developed a facile fabrication process of versatile antibody array biochips for reliable on-chip MALDI-TOF-MS analysis of multiple immuno-captured proteins. Hydrophilic gold arrays surrounded by super-hydrophobic surfaces were formed on a gold patterned biochip via spontaneous chemical or protein layer deposition. From antibody immobilization to MALDI matrix treatment, this hydrophilic/phobic pattern allowed highly consistent surface reactions on each gold spot. Various antibodies were immobilized on these gold spots both by covalent coupling or protein G binding. Four different protein markers were successfully analyzed on the present immuno-MALDI biochip from complex protein mixtures including serum samples. Tryptic digests of captured PSA protein were also effectively detected by on-chip MALDI-TOF-MS. Moreover, the present MALDI biochip can be directly applied to the SPR imaging system, by which antibody and subsequent antigen immobilization were successfully monitored. PMID:22087467

Kim, Young Eun; Yi, So Yeon; Lee, Chang-Soo; Jung, Yongwon; Chung, Bong Hyun

2011-11-15

70

Recent developments in methods and technology for analysis of biological samples by MALDI-TOF-MS  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization–time-of-flight mass spectrometry (MALDI-TOF-MS) is widely used in a variety of\\u000a fields because it has the characteristics of speed, ease of use, high sensitivity, and wide detectable mass range for obtaining\\u000a molecular weights and for structural characterization of macromolecules. In this article we summarize recent developments\\u000a in matrix additives, new matrices, and sample-pretreatment methods using off-probe or on-probe

Chensong Pan; Songyun Xu; Houjiang Zhou; Yu Fu; Mingliang Ye; Hanfa Zou

2007-01-01

71

Biomarker discovery with SELDI-TOF MS in human urine associated with early renal injury : evaluation with computational analytical tools  

Microsoft Academic Search

BACKGROUND: Urine proteomics is one of the key emerging technologies to discover new biomarkers for renal disease, which may be used in the early diagnosis, prognosis and treatment of patients. In the present study, we validated surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) for biomarker discovery in patients with mild ischaemic kidney injury. METHODS: We used first-morning mid-stream urine

K. J. A. van Houtte; Coby Laarakkers; Elena Marchiori; Peter Pickkers; Jack F. M. Wetzels; Johannes L. Willems; Lambert P. van den Heuvel; Frans G. M. Russel; Rosalinde Masereeuw

2007-01-01

72

MALDI-TOF MS of phosphatidylethanolamines: Different adducts cause different post source decay (PSD) fragment ion spectra  

Microsoft Academic Search

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly applied to lipids. However, positional acyl chain analysis of lipids by MALDI was so far scarcely described.In this paper, the fragmentation behavior of phosphatidylethanolamine (PE) is investigated by using post-source decay (PSD) MS. In dependence on the investigated adduct, significant differences could be obtained. It will be shown

Beate Fuchs; Celestina Schober; Grit Richter; Rosmarie Süß; Jürgen Schiller

2007-01-01

73

Enhancement of charge remote fragmentation in protonated peptides by high-energy CID MALDI-TOF-MS using “cold” matrices  

Microsoft Academic Search

Delayed extraction matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (DE-MALDI-TOF-MS) is employed to evaluate its potential for peptide sequencing using both post-source decay (PSD) and high-energy collision-induced dissociation (CID). This work provides evidence that complete amino-acid sequences may be obtained employing a dual approach including PSD of [M + H]+ ions using a “hot” matrix (?-cyano-4-hydroxycinnamic acid, CHCA), followed by

E. Stimson; O. Truong; W. J. Richter; M. D. Waterfield; A. L. Burlingame

1997-01-01

74

MALDI-TOF MS fingerprinting facilitates rapid discrimination of phylotypes I, II and III of Propionibacterium acnes.  

PubMed

Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used today for species determination of bacteria and fungi in routine microbiological laboratories, and can also be used for subtyping of bacteria, such as Bacteroides fragilis. Propionibacterium acnes is frequently referred to as an anaerobic skin commensal of relatively low pathogenicity. In addition to its accepted pathogenic role in acne, P. acnes is now emerging as an important opportunistic pathogen in many other clinical situations, including late-stage prosthetic joint infections, osteomyelitis, endocarditis, endophthalmitis, post-neurosurgical infections and possibly prostate cancer. At the population genetic level, P. acnes can be differentiated into a number of distinct phylogroups, known as types IA1, IA2, IB, IC, II and III, which may be associated with different types of infections and clinical conditions. The aim of the present study was to evaluate MS-based typing for resolution of these genetic groups after routine identification by MALDI-TOF MS (Bruker MALDI Biotyper). The software package ClinProTools 2.2 was used to analyze the protein based mass spectra of reference strains belonging to types IA, IB, IC, II and III. Phylogroup-specific peaks and peak shifts were then identified visually. In addition, peak variations between the different types of P. acnes were investigated by using FlexAnalysis 3.3 software (Bruker). A differentiating library was created, which was used to type further 48 clinical isolates of P. acnes. Typing data obtained by MALDI-TOF MS were then compared with the results from Multilocus Sequence Typing (MLST). Most of the clinical isolates (n = 19) belonged to the type IA grouping according to MALDI-TOF MS. By MLST, all isolates were identified as type IA1. Twenty-one clinical isolates belonged to the type IB cluster based on both MALDI-TOF MS and MLST typing. Eight clinical isolates were identified as type II strains by both typing methods and all the type III reference strains could be distinguished by the presence of a unique type III-specific peak (7238 Da) by the MALDI-TOF MS. Our study demonstrates that MALDI-TOF MS is a reliable and powerful tool for rapid identification and typing of P. acnes strains from the main genetic divisions of the species. PMID:23485355

Nagy, Elisabeth; Urbán, Edit; Becker, Simone; Kostrzewa, Markus; Vörös, Andrea; Hunyadkürti, Judit; Nagy, István

2013-02-26

75

Regiospecific Analysis of Mono and Diglycerides in Glycerolysis Products by GC × GC-TOF-MS  

Microsoft Academic Search

Comprehensive bidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF-MS) was used for\\u000a the characterization of regiospecific mono- and diglycerides (MG-DG) content in the glycerolysis products derived from five\\u000a different lipids included lard (LA), sun flower seed oil (SF), corn oil (CO), butter (BU), and palm oil (PA). The combination\\u000a of fast and high temperature non-orthogonal column set namely DB17ht

Dias Indrasti; Yaakob B. Che Man; Sung Tong Chin; Shuhaimi Mustafa; Dzulkifly Mat Hashim; Marina Abdul Manaf

2010-01-01

76

The Application of SELDI-TOF-MS in Clinical Diagnosis of Cancers  

PubMed Central

Cancer diagnosis is important, and the early diagnosis of cancers could predict a more successful treatment. The proteomic studies emerged to be useful in combined analyses of samples from patients and provide more accurate diagnosis when compared to the single-factor-based diagnosis. In recent years, cancer detection with surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF MS) is flourishing and brought significant progress in this area. This paper summarizes some recent results with this technique for cancer diagnosis.

Liu, Chibo

2011-01-01

77

MALDI-TOF MS Andromas strategy for the routine identification of bacteria, mycobacteria, yeasts, Aspergillus spp. and positive blood cultures.  

PubMed

All organisms usually isolated in our laboratory are now routinely identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using the Andromas software. The aim of this study was to describe the use of this strategy in a routine clinical microbiology laboratory. The microorganisms identified included bacteria, mycobacteria, yeasts and Aspergillus spp. isolated on solid media or extracted directly from blood cultures. MALDI-TOF MS was performed on 2665 bacteria isolated on solid media, corresponding to all bacteria isolated during this period except Escherichia coli grown on chromogenic media. All acquisitions were performed without extraction. After a single acquisition, 93.1% of bacteria grown on solid media were correctly identified. When the first acquisition was not contributory, a second acquisition was performed either the same day or the next day. After two acquisitions, the rate of bacteria identified increased to 99.2%. The failures reported on 21 strains were due to an unknown profile attributed to new species (9) or an insufficient quality of the spectrum (12). MALDI-TOF MS has been applied to 162 positive blood cultures. The identification rate was 91.4%. All mycobacteria isolated during this period (22) were correctly identified by MALDI-TOF MS without any extraction. For 96.3% and 92.2% of yeasts and Aspergillus spp., respectively, the identification was obtained with a single acquisition. After a second acquisition, the overall identification rate was 98.8% for yeasts (160/162) and 98.4% (63/64) for Aspergillus spp. In conclusion, the MALDI-TOF MS strategy used in this work allows a rapid and efficient identification of all microorganisms isolated routinely. PMID:22044600

Bille, E; Dauphin, B; Leto, J; Bougnoux, M-E; Beretti, J-L; Lotz, A; Suarez, S; Meyer, J; Join-Lambert, O; Descamps, P; Grall, N; Mory, F; Dubreuil, L; Berche, P; Nassif, X; Ferroni, A

2011-11-01

78

Automated Gain Control Ion Funnel Trap for Orthogonal Time-of-Flight Mass Spectrometry  

SciTech Connect

Time-of-flight mass spectrometry (TOF MS) is increasingly used in proteomics research. Herein, we report on the development and characterization of an ultra-sensitive TOF MS instrument equipped with an electrodynamic ion funnel trap (IFT) that employs an automatic gain control (AGC) capability. The IFT-TOF MS was coupled to a reverse-phase capillary liquid chromatography (RPLC) separation and evaluated in experiments with complex proteolytic digests. When applied to a global tryptic digest of Shewanella oneidensis proteins, an order-of-magnitude increase in sensitivity compared to that of the conventional continuous mode of operation was achieved due to efficient ion accumulation prior to TOF MS analysis. As a result of this sensitivity improvement and related improvement in mass measurement accuracy, the number of unique peptides identified in the AGC-IFT mode was 5-fold greater than that obtained in the continuous mode.

Ibrahim, Yehia M.; Belov, Mikhail E.; Liyu, Andrei V.; Smith, Richard D.

2008-07-15

79

Characterization of Microorganisms by MALDI Mass Spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for characterization and analysis of microorganisms, specifically bacteria, is described here as a rapid screening tool. The objective of this technique is not comprehensive protein analysis of a microorganism but rather a rapid screening of the organism and the accessible protein pattern for characterization and distinction. This method is based on the ionization

Catherine E. Petersen; Nancy B. Valentine; Karen L. Wahl

2008-01-01

80

Expanding the range of halogenated 1?-methyl-1,2?-bipyrroles (MBPs) using GC\\/ECNI-MS and GC × GC\\/TOF-MS  

Microsoft Academic Search

Halogenated 1?methyl-1,2?-bipyrroles (MBPs) have been identified worldwide in marine mammals. Here we present the tentative identification of previously undetected MBP congeners in Delpinus delphis blubber using gas chromatography\\/electron capture negative ion mass spectrometry (GC\\/ECNI-MS) and comprehensive two-dimensional gas chromatography\\/time of flight mass spectrometry (GC×GC\\/TOF-MS). This is the first report of 26 congeners. The presence of numerous partially halogenated congeners suggests

Kristin Pangallo; Robert K. Nelson; Emma L. Teuten; Byron E. Pedler; Christopher M. Reddy

2008-01-01

81

Application of electrospray mass spectrometry and matrix-assisted laser desorption ionization time-of-flight mass spectrometry for molecular weight assignment of peptides in complex mixtures  

Microsoft Academic Search

Electrospray mass spectrometry (ES\\/MS) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI\\/TOF\\/MS)\\u000a were used to provide mass spectra from seven elapid snake venoms. Spectral interpretation was much simpler for MALDI\\/TOF\\/MS.\\u000a ES\\/MS proved more useful for the provision of molecular weight data for very closely related peptides, but suppression of\\u000a higher molecular weight compounds was seen to occur during flow

John R. Perkins; Brian Smith; Richard T. Gallagher; Davis S. Jones; Stephen C. Davis; Andrew D. Hoffman; Kenneth B. Tomer

1993-01-01

82

Validation of LC-TOF-MS screening for drugs, metabolites, and collateral compounds in forensic toxicology specimens.  

PubMed

Liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) analysis provides an expansive technique for identifying many known and unknown analytes. This study developed a screening method that utilizes automated solid-phase extraction to purify a wide array of analytes involving stimulants, benzodiazepines, opiates, muscle relaxants, hypnotics, antihistamines, antidepressants and newer synthetic "Spice/K2" cannabinoids and cathinone "bath salt" designer drugs. The extract was applied to LC-TOF-MS analysis, implementing a 13 min chromatography gradient with mobile phases of ammonium formate and methanol using positive mode electrospray. Several common drugs and metabolites can share the same mass and chemical formula among unrelated compounds, but they are structurally different. In this method, the LC-TOF-MS was able to resolve many isobaric compounds by accurate mass correlation within 15 ppm mass units and a narrow retention time interval of less than 10 s of separation. Drug recovery yields varied among spiked compounds, but resulted in overall robust area counts to deliver an average match score of 86 when compared to the retention time and mass of authentic standards. In summary, this method represents a rapid, enhanced screen for blood and urine specimens in postmortem, driving under the influence, and drug facilitated sexual assault forensic toxicology casework. PMID:23118149

Guale, Fessessework; Shahreza, Shahriar; Walterscheid, Jeffrey P; Chen, Hsin-Hung; Arndt, Crystal; Kelly, Anna T; Mozayani, Ashraf

2012-11-01

83

TOF MS studies concerning the synthesis of BN and B-C-N nanaostructured materials by laser ablation  

Microsoft Academic Search

Time-of-flight mass spectroscopy (TOF MS) spectra of ions ablated from BN-ceramic, amorphous carbon, graphite and fullerene-60 targets were recorded at different experimental conditions. It was found that the TOF MS spectra significantly simplify as the energy density of the laser radiation was increased, and show temporal evolution as the distance between the target surface and work area of TOF MS

Dachun Huang; Vladimir I. Makarov; Arturo Hidalgo; Brad R. Weiner; Gerardo Morell

2006-01-01

84

Separation, identification, and profiling of membrane proteins by GFC/IEC/SDS-PAGE and MALDI TOF MS.  

PubMed

Membrane protein identification by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) requires that proteins be separated prior to MS analysis. After membrane solubilization with the nondenaturing detergent n-dodecyl-beta-D-maltoside, proteins can be separated by ion-exchange chromatography (IEC) and further resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). An additional separation step by gel filtration (GF) before IEC/SDS-PAGE can be required depending on the complexity of the membrane protein mixture. Staining of final SDS-PAGE gels allows one to establish simply the protein expression pattern of a membrane fraction and to profile responses. Moreover, in-gel digestion of hydrophobic integral proteins is valuable. Finally, the resolution capacity of this separation procedure allows identification of proteins by MALDI-TOF MS. The method is illustrated by application to plant and yeast plasma membrane and to plant vacuolar membrane. PMID:17093317

Szponarski, Wojciech; Delom, Frédéric; Sommerer, Nicolas; Rossignol, Michel; Gibrat, Rémy

2007-01-01

85

Detection of Bacteriocins by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry  

PubMed Central

The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection of bacteriocins was investigated. A 30-s water wash of the sample on the MALDI-TOF MS probe was effective in removing contaminants of the analyte. This method was used for rapid detection of nisin, pediocin, brochocin A and B, and enterocin A and B from culture supernatants and for detection of enterocin B throughout its purification.

Rose, Natisha L.; Sporns, Peter; McMullen, Lynn M.

1999-01-01

86

Coincidence experiments in desorption mass spectrometry  

NASA Astrophysics Data System (ADS)

The detection of coincidental signals can enhance the amount of information available in desorption time-of-flight mass spectrometry (TOF-MS) by identifying physical, chemical and/or spatial correlations between secondary ions. Detection of coincidental emissions requires that the target surface be bombarded with individual primary ions (keV or MeV), each resolved in time and space. This paper will discuss the application of coincidence counting to TOF-MS to: extract the secondary ion mass spectrum and secondary ion yields from an organic target produced by a single primary ion type when multiple primary ions simultaneously impact the sample; examine the metastable dissociation pathways and decay fractions of organic secondary ions using an ion-neutral correlation method; and study the chemical microhomogeneity (on the sub-?m scale) of a surface composed of two chemically distinct species.

Diehnelt, C. W.; English, R. D.; van Stipdonk, M. J.; Schweikert, E. A.

2002-06-01

87

[Analysis of gingerol-related compounds in fresh ginger by HPLC-ESI-Q-TOF-MS/MS].  

PubMed

To establish a rapid method for analysis of gingerol-related compounds in fresh ginger by using high performance liquid chromatography coupled with electron spray ionization-quadrupole-time of flight mass/mass spectrometry (HPLC-ESI-Q-TOF-MS/ MS). The gingerol-related compounds in fresh ginger was separated by an Inertsil ODS-SP column (4.6 mm x 250 mm, 5 microm) using a binary eluent under gradient conditions. The analytes were detected by ESI-Q-TOF-MS/MS in positive ion mode to obtain MS and MS/MS spectra and to extract molecular weights. From the MS data, the accurate molecular weights of gingerol-related compounds were obtained, and from the MS/MS data, the (+) ESI-Q-TOF-MS/MS fragments were obtained. 25 gingerol-related compounds were identified from fresh ginger by attentive studying on the mass spectra of compounds and comparing with reference data reported in the literature, respectively. This method was certified to be accurate and reliable and can be used for the rapid analysis of gingerol-related compounds in fresh ginger. PMID:22368858

Wang, Li; Fang, Lei; Zhao, Hengqiang; Wang, Shanshan; Du, Jinhua; Wang, Xiao

2011-12-01

88

Analysis of long-chain polyprenols using supercritical fluid chromatography and matrix-assisted laser desorption ionization time-of-flight mass spectrometry  

Microsoft Academic Search

The separation of long-chain polyprenols was successfully achieved using supercritical fluid chromatography (SFC). Each 100-mer greater component was separated using tetrahydrofuran as a mobile phase modifier. The molecular mass distributions derived from SFC analyses agreed with the results of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analyses. The number-average molecular mass calculated by MALDI-TOF-MS data were also in accord

T Bamba; E Fukusaki; Y Nakazawa; H Sato; K Ute; T Kitayama; A Kobayashi

2003-01-01

89

Accurate mass measurements for the confirmation of Sudan azo-dyes in hot chilli products by capillary liquid chromatography–electrospray tandem quadrupole orthogonal-acceleration time of flight mass spectrometry  

Microsoft Academic Search

The potential of capillary liquid chromatography (microLC)–quadrupole\\/time-of-flight mass spectrometry (Q-TOF MS) for the confirmation of Sudan I, II, III and IV azo-dyes as contaminants in hot-chilli food products was demonstrated. Using the microLC–electrospray ionization (ESI)–Q-TOF MS technique, accurate mass measurements of Sudan dyes were performed both on standard solutions and on matrices. Precision of exact mass measurements was calculated taking

F. Calbiani; M. Careri; L. Elviri; A. Mangia; I. Zagnoni

2004-01-01

90

MALDI-TOF MS of Trichoderma : a model system for the identification of microfungi  

Microsoft Academic Search

This investigation aimed to assess whether MALDI-TOF MS analysis of the proteome could be applied to the study of Trichoderma, a fungal genus selected because it includes many species and is phylogenetically well defined. We also investigated whether\\u000a MALDI-TOF MS analysis of peptide mass fingerprints would reveal apomorphies that could be useful in diagnosing species in\\u000a this genus. One hundred

Sophie De Respinis; Guido Vogel; Cinzia Benagli; Mauro Tonolla; Orlando Petrini; Gary J. Samuels

2010-01-01

91

Application of SELDI-TOF-MS in protein profiling: state of the art  

Microsoft Academic Search

Serum protein profiling by surface-enhanced laser desorption\\/ionization time-of-flight mass spectro- metry (SELDI-TOF-MS) appears to be an important diagnostic tool for a whole range of diseases. Sensi- tivities and specificities obtained with this new tech- nology often seem superior to those obtained with current biomarkers. However, reproducibility and standardization are still problematic. This presenta- tion explains the SELDI-TOF-MS technique and some

M. P. van DIEIJEN-VISSER; J. A. P. BONS; K. W. H. WODZIG

2007-01-01

92

Proteomic Analysis of Rat Plasma by SELDI-TOF-MS under the Condition of Prevention of Progressive Adriamycin Nephropathy Using Oral Adsorbent AST120  

Microsoft Academic Search

Aims: To determine changes in relative peak intensities of mass-to-charge ratio (m\\/z) between 2,000 and 15,000, which are difficult to evaluate by 2-dimensional gel electrophoresis, SELDI-TOF-MS (surface-enhanced laser desorption\\/ionization time of flight-mass spectrometry) proteomic changes in rat models of adriamycin nephropathy with or without AST-120 were investigated. Methods: A normal group (n = 5), an adriamycin nephropathy group (n =

Isao Ishikawa; Tomoyuki Hayama; Sachiko Yoshida; Mitsuhiro Asaka; Naohisa Tomosugi; Masataka Watanabe; Hideyuki Yamato; Mikio Sugano

2006-01-01

93

Development of a superconducting-phase-transition thermometer (SPT) for the application in a time-of-flight mass spectrometer (TOF-MS) for heavy-mass molecules  

NASA Astrophysics Data System (ADS)

We report on a newly developed detector based on a Superconducting-Phase-Transition Thermometer which is used in a Time-of-flight mass spectrometer for heavy molecules. It exhibits a sensitive area of 3.0×3.0mm2 and a time resolution of approximately 1.1?s. First measurements with our setup on heavy proteins up to 150,000amu are presented.

Rutzinger, S.; Christ, P.; Pröbst, F.; Seidel, W.; Uchaikin, S.; Stark, M.

2004-03-01

94

Identification of isoquercitrin metabolites produced by human intestinal bacteria using UPLC-Q-TOF/MS.  

PubMed

In this paper, ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and the MetaboLynx™ software combined with mass defect filtering were applied to identity the metabolites of isoquercitrin using an intestinal mixture of bacteria and 96 isolated strains from human feces. The human incubated samples collected for 72 h in the anaerobic incubator and extracted with ethyl acetate were analyzed by UPLC-Q-TOF/MS within 10 min. The parent compound and five metabolites were identified by eight isolated strains, including Bacillus sp. 17, Veillonella sp. 23 and 32 and Bacteroides sp. 40, 41, 56, 75 and 88 in vitro. The results indicate that quercetin, acetylated isoquercitrin, dehydroxylated isoquercitrin, hydroxylated quercetin and hydroxymethylated quercetin are the major metabolites of isoquercitrin. Furthermore, a possible metabolic pathway for the biotransformation of isoquercitrin was established in intestinal flora. This study will be helpful for understanding the metabolic route of isoquercitrin and the role of different intestinal bacteria in the metabolism of natural compounds. PMID:23018801

Lu, Linling; Qian, Dawei; Yang, Jing; Jiang, Shu; Guo, Jianming; Shang, Er-xin; Duan, Jin-ao

2012-09-28

95

Evaluation of automated direct sample introduction with comprehensive two-dimensional gas chromatography\\/time-of-flight mass spectrometry for the screening analysis of dioxins in fish oil  

Microsoft Academic Search

An automated direct sample introduction technique coupled to comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (DSI-GC×GC\\/TOF-MS) was applied for the development of a relatively fast and easy analytical screening method for 17 polychlorinated dibenzo-p-dioxins\\/dibenzofurans (PCDD\\/Fs) and 4 non-ortho polychlorinated biphenyls (PCBs) in fish oil. Comparison of instrumental performance between DSI-GC×GC\\/TOF-MS and the traditional gas chromatographic high resolution mass spectrometric

Eunha Hoh; Steven J. Lehotay; Katerina Mastovska; Janice K. Huwe

2008-01-01

96

A comparative study of the fragmentation of neutral lactooligosaccharides in negative-ion mode by UV-MALDI-TOF and UV-MALDI ion-trap\\/TOF mass spectrometry  

Microsoft Academic Search

Structure analyses of underivatized neutral lacto oligosaccharides are systematically performed by ultraviolet matrix-assisted\\u000a laser desorption\\/ionization time-of-flight mass spectrometry (UV-MALDI TOF MS) and UV-MALDI ion-trap time-of-flight mass spectrometry\\u000a (ion-trap\\/TOF MS) acquired in negative-ion mode. Interestingly, their fragmentation significantly differ each other. In postsource\\u000a decay (PSD) in UV-MALDI TOF MS, cross-ring cleavage at the reducing terminal predominates. On the other hand, glycosyl

Tohru Yamagaki; Hiroaki Suzuki; Kazuo Tachibana

2006-01-01

97

Efficient Analysis of Non-Polar Environmental Contaminants by MALDI-TOF MS with Graphene as Matrix  

NASA Astrophysics Data System (ADS)

In this Application Note, we describe, for the first time, the rapid analysis of hydrophobic compounds present in environmental contaminants, which includes polycyclic aromatic hydrocarbons (PAHs) and estrogen, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with the use of graphene as matrix. MALDI-TOF MS with conventional matrix has limitations in analyzing low-polarity compounds owing to their difficulty in ionization. We demonstrate that compared with conventional matrix, graphene displays higher desorption/ionization efficiencies for PAHs, and no fragment ions are observed. The method also holds potential in quantitative analysis. In addition, the ionization signal increases with the increasing number of benzene rings in the PAHs, suggesting that graphene binds to PAHs via ?-? stacking interactions. Furthermore, graphene as adsorbent for solid-phase extraction of coronene from river water sample displays good performance with a detection limit of 10-7 M. This work provides a novel and convenient method for analyzing low-polarity environmental contaminants by MALDI-TOF MS.

Zhang, Jing; Dong, Xiaoli; Cheng, Jinsheng; Li, Jinghong; Wang, Yinsheng

2011-07-01

98

GC-MS and MALDI-TOF MS profiling of sucrose esters from Nicotiana tabacum and N. rustica.  

PubMed

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has been applied for the first time to the analysis of the sucrose esters from the surface of Nicotiana L. leaves. The profiles obtained for the model plant N. tabacum were similar to those from the gas chromatography-flame ionization detector (GC-FID) analysis. The most reproducible results were obtained using a dihydroxybenzoic acid (DHB) matrix. The main advantage of this method is that crude plant extracts can be analysed without sample clean-up. GC-MS analysis of Aztec tobacco (N. rustica) extracts revealed the presence of three types of sucrose esters. All identified compounds had three C4-C8 acyl chains substituting the glucose moiety, while the fructose part of the molecule was substituted with 0, 1, or 2 acetyl groups. MALDI-TOF MS analysis of the sucrose ester fraction revealed the presence of compounds not eluting from a GC column. Combining the data from both GC-MS and MALDI-TOF MS experiments, we obtained a full sucrose ester profile, which is based on the molecular weight of the compounds and on the number of acyl chains in the molecule. PMID:23923618

Hali?ski, ?ukasz P; Stepnowski, Piotr

99

Top-down proteomic identification of furin-cleaved alpha-subunit of Shiga toxin 2 from Escherichia coli O157:H7 using MALDI-TOF-TOF-MS/MS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A method has been developed to identify the alpha-subunit of shiga toxin 2 (alpha-Stx2) from Escherichia coli O157:H7 using matrix-assisted laser desorption/ionization time-of-flight-time-of-flight tandem mass spectrometry (MALDI-TOF-TOF-MS/MS) and top-down proteomics using web-based software develo...

100

Induction and identification of disulfide-intact and disulfide-reduced beta-subunit of Shiga toxin 2 from Escherichia coli O157:H7 using MALDI-TOF-TOF-MS/MS and top-down proteomics  

Technology Transfer Automated Retrieval System (TEKTRAN)

The disulfide-intact and disulfide-reduced beta-subunit of Shiga toxin 2 (beta-Stx2) from Escherichia coli O157:H7 (strain EDL933) has been identified by matrix-assisted laser desorption/ionization time-of-flight-time-of-flight tandem mass spectrometry (MALDI-TOF-TOF-MS/MS) and top-down proteomic an...

101

Correlations between blood glucose and breath components from portable gas sensors and PTR-TOF-MS.  

PubMed

Acetone is one of the most abundant volatile compounds in the human breath and might be important for monitoring diabetic patients. Here, a portable acetone sensor consisting of flame-made, nanostructured, Si-doped WO3 sensing films was used to analyse the end tidal fraction of the breath (collected in Tedlar bags) from eight healthy volunteers after overnight fasting (morning) and after lunch (afternoon). After breath sampling, the gaseous components were also analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS), and each person's blood glucose level was measured. The portable sensor accurately detected the presence of acetone with fast response/recovery times (<12 s) and a high signal-to-noise ratio. Statistical analysis of the relationship between the PTR-TOF-MS measurements of breath gases (e.g., acetone, isoprene, ethanol and methanol), sensor response and the blood glucose level was performed for both sampling periods. The best correlations were found after overnight fasting (morning): in particular, between blood glucose level and breath acetone (Pearson's 0.98 and Spearman's 0.93). Whereas the portable sensor response correlated best with the blood glucose (Pearson's 0.96 and Spearman's 0.81) and breath acetone (Pearson's 0.92 and Spearman's 0.69). PMID:23959908

Righettoni, M; Schmid, A; Amann, A; Pratsinis, S E

2013-08-20

102

Profiling the ginsenosides of three ginseng products by lc-q-tof/ms.  

PubMed

Ginseng is a well-known herbal medicine that has been gaining increasingly popularity as a potential chemopreventive agent. In traditional Chinese medicine practice, white ginseng (WG), red ginseng (RG), and dali ginseng (DG) are 3 different ginseng-processed products used for different purposes. Although the morphological appearance and some constituents contained in these ginseng products are similar, their pharmacological activities are significantly different due to the varied types and quantity of ginsenosides in each product. In the present study, a practical method based on rapid liquid chromatography coupled with quadrupole time of flight mass spectrometry (LC-Q-TOF/MS) was developed to identify the chemical profiles of ginsenosides in these 3 ginseng products. The results demonstrated that a total of 55, 53, and 43 compounds were unambiguously assigned or tentatively identified in DG, WG, and RG samples, respectively. The featured compounds are mainly malonyl ginsenosides in WG, and decarboxyl products of mal-ginsenosides and the dehydrated compounds from polar ginsenosides were characteristic in RG, while DG contain some characteristic components present both in WG and RG. We presume that heating processing is the major factor affecting the chemical profile of ginseng products. The difference of chemical information revealed by LC-Q-TOF/MS could be used to discriminate the WG, RG, and DG samples. PMID:23550959

Chu, Chu; Xu, Shaojing; Li, Xingnuo; Yan, Jizhong; Liu, Li

2013-04-02

103

Rapid analysis of PAHs in fly ash using thermal desorption and fast GC-TOF-MS.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are semivolatile organic compounds that may form as a result of incomplete combustion of organic materials. After they are produced in combustion systems, this class of chemicals can be emitted with flue gas or adsorbed in combustion residues such as fly ash and bed ash. The purpose of this study is to develop a thermal extraction (TE) method for the determination of the 16 U.S. Environmental Protection Agency specified priority PAH pollutants in fly ash. The commonly used method for determining PAHs in solid wastes is solvent extraction followed by gas chromatography (GC) or GC-mass spectrometry (MS) analysis. This method is work- and time-intensive and produces solvent waste. In this study, the samples are analyzed using TE and fast GC-time-of-flight (TOF)-MS. The complete process from extraction to analysis can be achieved in less than one hour. The results indicate that the TE-GC-TOF-MS method has good linear range from 1.5 to 60 micro g/g for all 16 PAHs. The recoveries for the 16 target PAHs vary between 83% and 94%. PMID:12841952

Zou, Daozhong; Liu, Kunlei; Pan, Wei-Ping; Riley, John T; Xu, Yiqan

104

Low temperature followed by matrix solid-phase dispersion-sonication procedure for the determination of multiclass pesticides in palm oil using LC-TOF-MS  

Microsoft Academic Search

A simple and effective multiresidue method based on precipitation at low temperature followed by matrix solid-phase dispersion-sonication was developed and validated to determine dimethoate, malathion, carbaryl, simazine, terbuthylazine, atrazine and diuron in palm oil using liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS). Liquid–liquid extraction (LLE) followed by low temperature method were optimized by studying the effect of type and volume of

Elham Sobhanzadeh; Nor Kartini Abu Bakar; Mhd Radzi Bin Abas; Keivan Nemati

2011-01-01

105

Comparison of different extraction methods for the determination of statin drugs in wastewater and river water by HPLC\\/Q-TOF-MS  

Microsoft Academic Search

Three preconcentration techniques including solid phase extraction (SPE), dispersive liquid–liquid microextraction (DLLME) and stir-bar sorptive extraction (SBSE) have been optimized and compared for the analysis of six hypolipidaemic statin drugs (atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin) in wastewater and river water samples by high performance liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (HPLC\\/Q-TOF-MS). Parameters that affect the efficiency of

Julia Martín; Wolfgang Buchberger; Esteban Alonso; Markus Himmelsbach; Irene Aparicio

2011-01-01

106

Rapid determination of total solanesol in tobacco leaf by ultrasound-assisted extraction with RP-HPLC and ESI-TOF\\/MS  

Microsoft Academic Search

A reliable and rapid method based on high-performance liquid chromatography (HPLC-UV) and positive ion electrospray-time of flight mass spectrometry (ESI-TOF\\/MS) has been developed for the characterization and quantification of solanesol in extracts of tobacco leaves from different sources. The solanesol was extracted from tobacco leaf via saponification and ultrasonic-assist extraction, and the extraction conditions were optimized. The HPLC conditions are

Junhui Chen; Xianping Liu; Xiaoqin Xu; Frank Sen-Chun Lee; Xiaoru Wang

2007-01-01

107

Rapid Identification of Staphylococci Isolated in Clinical Microbiology Laboratories by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) of intact bacteria yields a reproducible spectrum depending upon growth conditions, strain, or species. Using whole viable bacteria we describe here the application of MALDI-TOF-MS to the identification of coag- ulase-negative staphylococci (CoNS). Our aim was, once a bacterium has been recognized as Micrococ- caceae, to identify peaks in the spectrum

Etienne Carbonnelle; Jean-Luc Beretti; Stephanie Cottyn; Gilles Quesne; Patrick Berche; Xavier Nassif; Agnes Ferroni; Hopital Necker-Enfants Malades

2007-01-01

108

Angiotensin II-Acetylcholine Noncovalent Complexes Analyzed With MALDI-Ion Mobility-TOF MS  

PubMed Central

Matrix-assisted laser desorption ionization–ion mobility–orthogonal time-of-flight mass spectrometry (MALDI-IM-oTOF MS) is a new technique that allows laser desorbed ions to be preseparated on the basis of their shape prior to mass analysis. Using this instrument, we tested the postulate that addition of a quaternary ammonium compound such as acetylcholine to the model phosphorylated peptide angiotensin II would enhance its detection by MALDI in two ways. First of all, the acetylcholine–peptide complex could ionize more efficiently than the bare phosphopeptide. Furthermore, the ion mobility could separate the complex ion on the basis of its charge/volume from isobaric interferences, which would otherwise limit detection sensitivity.

Woods, Amina S.; Fuhrer, Katrin; Gonin, Marc; Egan, Tom; Ugarov, Michael; Gillig, Kent J.; Schultz, J. Albert

2003-01-01

109

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS  

SciTech Connect

Combustion chamber deposits (CCDs) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components [1]. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recent advances in MS have opened new possibilities for analysis of CCDs. Here we report initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.

Reynolds, J G; Shields, S J; Roos, J W

2001-06-14

110

The MALDI-TOF Mass Spectrometric View of the Plasma Proteome and Peptidome  

Microsoft Academic Search

Background: Matrix-assisted laser desorption\\/ioniza- tion time-of-flight mass spectrometry (MALDI-TOF MS) and the related technique, surface-enhanced laser desorption\\/ionization (SELDI)-TOF MS, are being ap- plied widely to analyze serum or plasma specimens for potential disease markers. Methods: Reports on the basic principles and applica- tions of MALDI-TOF MS were reviewed and related to information on abundance and masses of major plasma proteins.

Glen L. Hortin

2006-01-01

111

Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry  

ERIC Educational Resources Information Center

|Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

2007-01-01

112

Advances in quantitative hepcidin measurements by time-of-flight mass spectrometry  

Microsoft Academic Search

Assays for the detection of the iron regulatory hormone hepcidin in plasma or urine have not yet been widely available, whereas quantitative comparisons between hepcidin levels in these different matrices were thus far even impossible due to technical restrictions. To circumvent these limitations, we here describe several advances in time-of flight mass spectrometry (TOF MS), the most important of which

Dorine W. Swinkels; Domenico Girelli; Coby Laarakkers; Joyce Kroot; Natascia Campostrini; Erwin H. J. M. Kemna; Harold Tjalsma

2008-01-01

113

OLIGOSACCHARIDE STRUCTURES STUDIED BY HYDROGEN-DEUTERIUM EXCHANGE (HX) AND MALDI-TOF MASS SPECTROMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydrogen-deuterium exchange matrix-assisted laser desorption/ionization - time-of-flight mass spectrometry (HX-MALDI-TOF MS) is reported for the first time for the determination of exchangeable protons in diverse oligosaccharide and glycoconjugate structures. The method is generally analogous to th...

114

Novel Mass Spectrometry-Based Tool for Genotypic Identification of Mycobacteria  

Microsoft Academic Search

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) after base-specific cleavage of PCR amplified and in vitro-transcribed 16S rRNA gene (rDNA) was used for the identification of mycobacteria. Full-length 16S rDNA reference sequences of 12 type strains of Mycobacterium spp. frequently isolated from clinical specimens were determined by PCR, cloning, and sequencing. For MALDI-TOF MS-based comparative sequence analysis,

Michael Lefmann; Christiane Honisch; Sebastian Bocker; Niels Storm; Cord Schlotelburg; Annette Moter; Dirk van den Boom; Ulf B. Gobel

2004-01-01

115

Mass spectrometry: a revolution in clinical microbiology?  

PubMed

Recently, different bacteriological laboratory interventions that decrease reporting time have been developed. These promising new broad-based techniques have merit, based on their ability to identify rapidly many bacteria, organisms difficult to grow or newly emerging strains, as well as their capacity to track disease transmission. The benefit of rapid reporting of identification and/or resistance of bacteria can greatly impact patient outcomes, with an improvement in the use of antibiotics, in the reduction of the emergence of multidrug resistant bacteria and in mortality rates. Different techniques revolve around mass spectrometry (MS) technology: matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), PCR combined with electrospray ionization-mass spectrometry (PCR/ESIMS), iPLEX MassArray system and other new evolutions combining different techniques. This report emphasizes the (r)evolution of these technologies in clinical microbiology. PMID:23072853

Lavigne, Jean-Philippe; Espinal, Paula; Dunyach-Remy, Catherine; Messad, Nourredine; Pantel, Alix; Sotto, Albert

2013-02-01

116

Metabolomics of transgenic maize combining Fourier transform-ion cyclotron resonance-mass spectrometry, capillary electrophoresis-mass spectrometry and pressurized liquid extraction  

Microsoft Academic Search

In this work, the potential of combining capillary electrophoresis-time-of-flight-mass spectrometry (CE-TOF-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) for metabolomics of genetically modified organisms (GMOs) is demonstrated. Thus, six different varieties of maize, three of them transgenic (PR33P66 Bt, Tietar Bt and Aristis Bt) and their corresponding isogenic lines (PR33P66, Tietar and Aristis) grown under the same field conditions, were

Carlos Leon; Irene Rodriguez-Meizoso; Marianna Lucio; Virginia Garcia-Cañas; Elena Ibañez; Philippe Schmitt-Kopplin; Alejandro Cifuentes

2009-01-01

117

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS  

SciTech Connect

Combustion chamber deposits (CCD) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recently, we have reported on the metal structure by XPS and XAS of several deposits from a GM 3800 engine generated using a standard fuel and one that contains low levels of the gasoline anti-knock additive, MMT. Here we report the initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.

Reynolds, J G; Shields, S J; Roos, J W

2001-06-14

118

Direct screening of herbal blends for new synthetic cannabinoids by MALDI-TOF MS.  

PubMed

Since 2004, a number of herbal blends containing different synthetic compounds mimicking the pharmacological activity of cannabinoids and displaying a high toxicological potential have appeared in the market. Their availability is mainly based on the so-called "e-commerce", being sold as legal alternatives to cannabis and cannabis derivatives. Although highly selective, sensitive, accurate, and quantitative methods based on GC-MS and LC-MS are available, they lack simplicity, rapidity, versatility and throughput, which are required for product monitoring. In this context, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) offers a simple and rapid operation with high throughput. Thus, the aim of the present work was to develop a MALDI-TOF MS method for the rapid qualitative direct analysis of herbal blend preparations for synthetic cannabinoids to be used as front screening of confiscated clandestine preparations. The sample preparation was limited to herbal blend leaves finely grinding in a mortar and loading onto the MALDI plate followed by addition of 2 µl of the matrix/surfactant mixture [?-cyano-4-hydroxy-cinnamic acid/cetyltrimethylammonium bromide (CTAB)]. After drying, the sample plate was introduced into the ion source for analysis. MALDI-TOF conditions were as follows: mass spectra were analyzed in the range m/z 150-550 by averaging the data from 50 laser shots and using an accelerating voltage of 20?kV. The described method was successfully applied to the screening of 31 commercial herbal blends, previously analyzed by GC-MS. Among the samples analyzed, 21 contained synthetic cannabinoids (namely JWH-018, JWH-073, JWH-081, JWH-250, JWH-210, JWH-019, and AM-694). All the results were in agreement with GC-MS, which was used as the reference technique. PMID:22282100

Gottardo, Rossella; Chiarini, Anna; Dal Prà, Ilaria; Seri, Catia; Rimondo, Claudia; Serpelloni, Giovanni; Armato, Ubaldo; Tagliaro, Franco

2012-01-01

119

Characterization of Nucleosides and Nucleobases in Natural Cordyceps by HILIC-ESI/TOF/MS and HILIC-ESI/MS.  

PubMed

A method combining hydrophilic interaction chromatography (HILIC) and electrospray ionization mass spectrometry (ESI-MS) was developed for the characterization and determination of natural Cordyceps. Separation was achieved on a Waters Xbridge Amide column with gradient elution. Identification of 15 target nucleosides and nucleobases was based on retention time, UV spectra and mass measurements of the protonated molecules ([M+H]+) and main fragment ions (ESI-TOF/MS). Eight non-target compounds were tentatively identified by ESI-TOF/MS. The 15 target compounds were quantified by HILIC-ESI-MS/MS using time-programmed selective ion monitoring or multiple reaction monitoring in positive-ion mode under optimized mass conditions. This technique showed good linearity, repeatability and recovery. This approach was also successfully implemented in the analysis of nucleosides and nucleobases in 12 batches of natural Cordyceps samples that were collected from different regions in China. The developed HILIC-ESI-MS method exhibited clear advantages in identifying and determining highly polar bioactive components in Cordyceps, as well as their quality control. PMID:23955321

Zhao, Heng-Qiang; Wang, Xiao; Li, Hong-Mei; Yang, Bin; Yang, Hong-Jun; Huang, Luqi

2013-08-15

120

MALDI TOF MS profiling of bacteria at the strain level: a review.  

PubMed

Since the advent of the use of matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS) as a tool for microbial characterization, efforts to increase the taxonomic resolution of the approach have been made. The rapidity and efficacy of the approach have suggested applications in counter-bioterrorism, prevention of food contamination, and monitoring the spread of antibiotic-resistant bacteria. Strain-level resolution has been reported with diverse bacteria, using library-based and bioinformatics-enabled approaches. Three types of characterization at the strain level have been reported: strain categorization, strain differentiation, and strain identification. Efforts to enhance the library-based approach have involved sample pre-treatment and data reduction strategies. Bioinformatics approaches have leveraged the ever-increasing amount of publicly available genomic and proteomic data to attain strain-level characterization. Bioinformatics-enabled strategies have facilitated strain characterization via intact biomarker identification, bottom-up, and top-down approaches. Rigorous quantitative and advanced statistical analyses have fostered success at the strain level with both approaches. Library-based approaches can be limited by effects of sample preparation and culture conditions on reproducibility, whereas bioinformatics-enabled approaches are typically limited to bacteria, for which genetic and/or proteomic data are available. Biological molecules other than proteins produced in strain-specific manners, including lipids and lipopeptides, might represent other avenues by which strain-level resolution might be attained. Immunological and lectin-based chemistries have shown promise to enhance sensitivity and specificity. Whereas the limits of the taxonomic resolution of MALDI TOF MS profiling of bacteria appears bacterium-specific, recent data suggest that these limits might not yet have been reached. PMID:22996584

Sandrin, Todd R; Goldstein, Jason E; Schumaker, Stephanie

2012-09-19

121

High Throughput Detection of Tetracycline Residues in Milk Using Graphene or Graphene Oxide as MALDI-TOF MS Matrix  

NASA Astrophysics Data System (ADS)

In this work, a new pre-analysis method for tetracyclines (TCs) detection from the milk samples was established. As a good accomplishment for the existing accurate quantification strategies for TCs detection, the new pre-analysis method was demonstrated to be simple, sensitive, fast, cost effective, and high throughput, which would do a great favor to the routine quality pre-analysis of TCs from milk samples. Graphene or graphene oxide was utilized, for the first time, as a duel-platform to enrich and detect the TCs by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). All together, four TCs were chosen as models: tetracycline, oxytetracycline, demeclocycline, and chlortetracycline. Due to the excellent electronic, thermal, and mechanical properties, graphene and graphene oxide were successfully applied as matrices for MALDI-TOF MS with free background inference in low mass range. Meanwhile, graphene or graphene oxide has a large surface area and strong interaction force with the analytes. By taking the advantage of these features, TCs were effectively enriched with the limit of detection (LOD) as low as 2 nM.

Liu, Junyan; Liu, Yang; Gao, Mingxia; Zhang, Xiangmin

2012-08-01

122

MULTIPLEXED ION MOBILITY SPECTROMETRY - ORTHOGONAL TIME-OF-FLIGHT MASS SPECTROMETRY  

PubMed Central

Ion mobility spectrometry (IMS) coupled to orthogonal time-of-flight mass spectrometry (oTOF) has shown significant promise for the characterization of complex biological mixtures. The enormous complexity of biological samples (e.g. from proteomics) and the need for both biological and technical analysis replicates imposes major challenges for multidimensional separation platforms in regard to both sensitivity and sample throughput. A major attraction of the IMS-TOF MS platform is separation speeds exceeding that of conventional condensed-phase separations by orders of magnitude. Known limitations of the IMS-TOF MS platforms include the need for extensive signal averaging due to factors that include significant ion losses in the IMS-TOF interface and an ion utilization efficiency of less than ~1% with continuous ion sources (e.g. ESI). We have developed a new multiplexed ESI-IMS-TOF mass spectrometer that enables lossless ion transmission through the IMS-TOF as well as a utilization efficiency of >50% for ions from the ESI source. Initial results with a mixture of peptides show a ~10-fold increase in signal-to-noise ratio with the multiplexed approach compared to a signal averaging approach, with no reduction in either IMS or TOF MS resolution.

Belov, Mikhail E.; Buschbach, Michael A.; Prior, David C.; Tang, Keqi; Smith, Richard D.

2012-01-01

123

Multiplexed Ion Mobility Spectrometry - Orthogonal Time-Of-Flight Mass Spectrometry  

SciTech Connect

Ion mobility spectrometry (IMS) coupled to orthogonal time-of-flight mass spectrometry (TOF) has shown significant promise for the characterization of complex biological mixtures. The enormous complexity of biological samples (e.g. from proteomics) and the need for both biological and technical analysis replicates imposes major challenges for multidimensional separation platforms in regard to both sensitivity and sample throughput. A major potential attraction of the IMS-TOF MS platform is separation speeds exceeding that of conventional condensed-phase separations by orders of magnitude. Known limitations of the IMS-TOF MS platforms that presently mitigate this attraction include the need for extensive signal averaging due to factors that include significant ion losses in the IMS-TOF interface and an ion utilization efficiency of less than ~1% with continuous ion sources (e.g. ESI). We have developed a new multiplexed ESI-IMS-TOF mass spectrometer that enables lossless ion transmission through the IMS-TOF as well as a utilization efficiency of >50% for ions from the ESI source. Initial results with a mixture of peptides show a ~10-fold increase in signal-to-noise ratio with the multiplexed approach compared to a signal averaging approach, with no reduction in either IMS or TOF MS resolution.

Belov, Mikhail E.; Buschbach, Michael A.; Prior, David C.; Tang, Keqi; Smith, Richard D.

2007-03-15

124

Partially oxidised organic components in urban aerosol using GCXGC-TOF/MS  

NASA Astrophysics Data System (ADS)

Partially oxidised organic compounds associated with PM2.5 aerosol collected in London, England, have been analysed using direct thermal desorption coupled to comprehensive gas chromatography-time of flight mass spectrometry (GCXGC-TOF/MS). Over 10000 individual organic components were isolated from around 10µg of aerosol material in a single procedure and with no sample pre-treatment. Chemical functionalities observed using this analytical technique ranged from alkanes to poly-oxygenated species. The chemical band structures commonly used in GCXGC for group type identifications overlap for this sample type, and have required mass spectrometry as an additional level of instrument dimensionality. An investigation of oxygenated volatile organic compounds (o-VOC) contained within urban aerosol has been performed and in a typical sample around 130 o-VOCs were identified based on retention behaviour and spectral match. In excess of 100 other oxygenated species were also observed but lack of mass spectral library or pure components prevents positive identification. Many of the carbonyl species observed could be mechanistically linked to gas phase aromatic hydrocarbon oxidation and there is good agreement in terms of speciation between the urban samples analysed here and those degradation products observed in smog chamber experiments of aromatic oxidation. The presence of partially oxidised species such as linear chain aldehydes and ketones and cyclic products such as furanones suggests that species generated early in the oxidative process may undergo gas to particle partitioning despite their relatively high volatility.

Hamilton, J. F.; Webb, P. J.; Lewis, A. C.; Hopkins, J. R.; Smith, S.; Davy, P.

2004-08-01

125

Leptospira spp. strain identification by MALDI TOF MS is an equivalent tool to 16S rRNA gene sequencing and multi locus sequence typing (MLST)  

PubMed Central

Background In this study mass spectrometry was used for evaluating extracted leptospiral protein samples and results were compared with molecular typing methods. For this, an extraction protocol for Leptospira spp. was independently established in two separate laboratories. Reference spectra were created with 28 leptospiral strains, including pathogenic, non-pathogenic and intermediate strains. This set of spectra was then evaluated on the basis of measurements with well-defined, cultured leptospiral strains and with 16 field isolates of veterinary or human origin. To verify discriminating peaks for the applied pathogenic strains, statistical analysis of the protein spectra was performed using the software tool ClinProTools. In addition, a dendrogram of the reference spectra was compared with phylogenetic trees of the 16S rRNA gene sequences and multi locus sequence typing (MLST) analysis. Results Defined and reproducible protein spectra using MALDI-TOF MS were obtained for all leptospiral strains. Evaluation of the newly-built reference spectra database allowed reproducible identification at the species level for the defined leptospiral strains and the field isolates. Statistical analysis of three pathogenic genomospecies revealed peak differences at the species level and for certain serovars analyzed in this study. Specific peak patterns were reproducibly detected for the serovars Tarassovi, Saxkoebing, Pomona, Copenhageni, Australis, Icterohaemorrhagiae and Grippotyphosa. Analysis of the dendrograms of the MLST data, the 16S rRNA sequencing, and the MALDI-TOF MS reference spectra showed comparable clustering. Conclusions MALDI-TOF MS analysis is a fast and reliable method for species identification, although Leptospira organisms need to be produced in a time-consuming culture process. All leptospiral strains were identified, at least at the species level, using our described extraction protocol. Statistical analysis of the three genomospecies L. borgpetersenii, L. interrogans and L. kirschneri revealed distinctive, reproducible differentiating peaks for seven leptospiral strains which represent seven serovars. Results obtained by MALDI-TOF MS were confirmed by MLST and 16S rRNA gene sequencing.

2012-01-01

126

Real-Time Identification of Bacteria and Candida Species in Positive Blood Culture Broths by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry?  

PubMed Central

Delays in the identification of microorganisms are a barrier to the establishment of adequate empirical antibiotic therapy of bacteremia. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) allows the identification of microorganisms directly from colonies within minutes. In this study, we have adapted and tested this technology for use with blood culture broths, thus allowing identification in less than 30 min once the blood culture is detected as positive. Our method is based on the selective recovery of bacteria by adding a detergent that solubilizes blood cells but not microbial membranes. Microorganisms are then extracted by centrifugation and analyzed by MALDI-TOF-MS. This strategy was first tested by inoculating various bacterial and fungal species into negative blood culture bottles. We then tested positive patient blood or fluid samples grown in blood culture bottles, and the results obtained by MALDI-TOF-MS were compared with those obtained using conventional strategies. Three hundred twelve spiked bottles and 434 positive cultures from patients were analyzed. Among monomicrobial fluids, MALDI-TOF-MS allowed a reliable identification at the species, group, and genus/family level in 91%, 5%, and 2% of cases, respectively, in 20 min. In only 2% of these samples, MALDI-TOF MS did not yield any result. When blood cultures were multibacterial, identification was improved by using specific databases based on the Gram staining results. MALDI-TOF-MS is currently the fastest technique to accurately identify microorganisms grown in positive blood culture broths.

Ferroni, Agnes; Suarez, Stephanie; Beretti, Jean-Luc; Dauphin, Brunhilde; Bille, Emmanuelle; Meyer, Julie; Bougnoux, Marie-Elisabeth; Alanio, Alexandre; Berche, Patrick; Nassif, Xavier

2010-01-01

127

Evaluation of Fructooligosaccharides and Inulins as Potentially Health Benefiting Food Ingredients by HPAEC-PED and MALDI-TOF MS.  

PubMed

This paper describes the complementarity of high-performance anion exchange chromatography coupled with pulsed electrochemical detection (HPAEC-PED) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) to evaluate commercial available fructans (fructooligosaccharides (FOS) and inulins), having different degrees of polymerization (DP) which are usually employed by food industry as functional ingredients either for their prebiotic properties or as a fat replacer, giving a fat-like mouth feel and texture. The developed HPAEC-PED methods are able to analyze FOS (fructans with DP 3-10) and inulins (DP ranging from 3 to 80) with a good resolution and relatively short retention times to evaluate structural differences between fructooligosaccharide and inulins and the possible presence of inulooligosaccharides as well as of branching. To characterize FOS and inulin at different degrees of polymerization and to assure correct molecular assignment, MALDI-TOF MS analysis was also investigated. The 2,5-dihydroxy benzoic acid (2,5-DHB) was found to be the best matrix for FOS analysis as Actilight and Raftilose P95 products, while 3-aminoquinoline (3-AQ) seems to be the best matrix for inulin with higher DP. The applicability of the optimized methods to the identification and determination of FOS contained in a symbiotic milk as well as a type of inulin added as functional ingredient to a cooked ham is demonstrated. PMID:20140077

Borromei, Chiara; Careri, Maria; Cavazza, Antonella; Corradini, Claudio; Elviri, Lisa; Mangia, Alessandro; Merusi, Cristiana

2009-03-18

128

Evaluation of Fructooligosaccharides and Inulins as Potentially Health Benefiting Food Ingredients by HPAEC-PED and MALDI-TOF MS  

PubMed Central

This paper describes the complementarity of high-performance anion exchange chromatography coupled with pulsed electrochemical detection (HPAEC-PED) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) to evaluate commercial available fructans (fructooligosaccharides (FOS) and inulins), having different degrees of polymerization (DP) which are usually employed by food industry as functional ingredients either for their prebiotic properties or as a fat replacer, giving a fat-like mouth feel and texture. The developed HPAEC-PED methods are able to analyze FOS (fructans with DP 3–10) and inulins (DP ranging from 3 to 80) with a good resolution and relatively short retention times to evaluate structural differences between fructooligosaccharide and inulins and the possible presence of inulooligosaccharides as well as of branching. To characterize FOS and inulin at different degrees of polymerization and to assure correct molecular assignment, MALDI-TOF MS analysis was also investigated. The 2,5-dihydroxy benzoic acid (2,5-DHB) was found to be the best matrix for FOS analysis as Actilight and Raftilose P95 products, while 3-aminoquinoline (3-AQ) seems to be the best matrix for inulin with higher DP. The applicability of the optimized methods to the identification and determination of FOS contained in a symbiotic milk as well as a type of inulin added as functional ingredient to a cooked ham is demonstrated.

Borromei, Chiara; Careri, Maria; Cavazza, Antonella; Corradini, Claudio; Elviri, Lisa; Mangia, Alessandro; Merusi, Cristiana

2009-01-01

129

Peptidomic analysis of Chinese shrimp ( Fenneropenaeus chinensis) hemolymph by magnetic bead-based MALDI-TOF MS  

NASA Astrophysics Data System (ADS)

Peptides in shrimp hemolymph play an important role in the innate immune response. Analysis of hemolymph will help to detect and identify potential novel biomarkers of microbial infection. We used magnetic bead-based purification (ClinProt system) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) to characterize shrimp hemolymph peptides. Shrimp serum and plasma were used as the source of samples for comparative analysis, and it was found that serum was more suitable for shrimp hemolymph peptidomic analysis. To screen potential specific biomarkers in serum of immune-challenged shrimps, we applied magnetic bead-based MALDI-TOF MS to serum samples from 10 immune-challenged and 10 healthy shrimps. The spectra were analyzed using FlexAnalysis 3.0 and ClinProTools 2.1 software. Thirteen peptide peaks significantly different between the two groups were selected as candidate biomarkers of lipopolysaccharide (LPS)-infection. The diagnostic model established by genetic algorithm using five of these peaks was able to discriminate LPS-challenged shrimps from healthy control shrimps with a sensitivity of 90% and a specificity of 100%. Our approach in MALDITOF MS-based peptidomics is a powerful tool for screening bioactive peptides or biomarkers derived from hemolymph, and will help to enable a better understanding of the innate immune response of shrimps.

Wang, Baojie; Liu, Mei; Jiang, Keyong; Zhang, Guofan; Wang, Lei

2013-03-01

130

Characterization of the cultivable microbial community in a spinach-processing plant using MALDI-TOF MS.  

PubMed

A better and regular control of the production chain of fresh fruits and vegetables is necessary, because a contamination of the product by human- and phyto-pathogenic microorganisms may result in high losses during storage and poses a threat to human health. Therefore, detailed knowledge about the occurrence and the diversity of microorganisms within single processing steps is required to allow target-oriented produce safety control. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was successfully used to identify bacterial colonies. Bacteria can be identified with high accuracy by comparing them with generated spectra of a reference database. In this study, spinach and wash water samples were taken of the complete process line of a spinach-washing plant. Bacteria in the samples were grown on plate-count, Arcobacter selective, marine and blood agar. In total, 451 colonies were evaluated by MALDI-TOF MS, 16S rRNA gene sequence and phylogenetic analysis. 50% of the detected species belonged to the class of Gammaproteobacteria. Firmicutes were present with 22%. Mostly, the detected species showed 16S rRNA gene sequence dissimilarities larger than 1% to known reference species and, hence, could not be assigned to a distinct species. However, many isolated species belonged to genera which contain pathogenic or opportunistic pathogenic bacteria. In addition, the bacterial diversity on the spinach surface increased after the first washing step indicating a process-borne contamination of the spinach. PMID:23541209

Hausdorf, Lena; Mundt, Kerstin; Winzer, Michaela; Cordes, Christiana; Fröhling, Antje; Schlüter, Oliver; Klocke, Michael

2012-11-07

131

Mono-aromatic complexity in urban air and gasoline assessed using comprehensive GC and fast GC-TOF/MS.  

NASA Astrophysics Data System (ADS)

Two state-of-the-art analytical techniques have been used to assess mono-aromatic complexity in gasoline, gasoline vapors and polluted urban air. A comparison of comprehensive gas chromatography (GCxGC) and fast gas chromatography - time-of-flight mass spectrometry (GC-TOF-MS) has been made, with emphasis on the ability of each technique to speciate at high isomeric complexity. The high spectral acquisition rates from TOF-MS gave improved peak deconvolution of overlapping analytes when compared to standard quadrupole configurations, with 89 mono-aromatic isomers isolated in gasoline in a 200 s GC separation. Highest resolution was obtained using GCxGC, isolating 140 mono-aromatics, using combined column retention behavior for analyte identification. Analysis of urban air using GCxGC indicated the presence of 136 mono-aromatic species with up to 7 carbon substituents on the ring. Comparison of 3D GCxGC chromatograms for air and gasoline vapors demonstrated visually the impact of evaporative emission sources in urban environments. The potential contribution of larger mono-aromatic compounds as precursors to both photochemical ozone and secondary organic aerosol is discussed along with the implications on modeling OH chemistry in polluted air.

Hamilton, J. F.; Lewis, A. C.; Lewis, A. C.

2001-12-01

132

Multilocus Sequence Typing of Streptococcus pneumoniae by Use of Mass Spectrometry ?  

PubMed Central

Multilocus sequence typing (MLST) is an important tool for the global surveillance of bacterial pathogens that is performed by comparing the sequences of designated housekeeping genes. We developed and tested a novel mass spectrometry-based method for MLST of Streptococcus pneumoniae. PCR amplicons were subjected to in vitro transcription and base-specific cleavage, followed by analysis of the resultant fragments by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Comparison of the cleavage fragment peak patterns to a reference sequence set permitted automated identification of alleles. Validation experiments using 29 isolates of S. pneumoniae revealed that the results of MALDI-TOF MS MLST matched those obtained by traditional sequence-based MLST for 99% of alleles and that the MALDI-TOF MS method accurately identified two single-nucleotide variations. The MADLI-TOF MS method was then used for MLST analysis of 43 S. pneumoniae isolates from Papua New Guinean children. The majority of the isolates present in this population were not clonal and contained seven new alleles and 30 previously unreported sequence types.

Dunne, Eileen M.; Ong, Eng Kok; Moser, Ralf J.; Siba, Peter M.; Phuanukoonnon, Suparat; Greenhill, Andrew R.; Robins-Browne, Roy M.; Mulholland, E. Kim; Satzke, Catherine

2011-01-01

133

Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Identification of Mycobacteria in Routine Clinical Practice  

PubMed Central

Background Non-tuberculous mycobacteria recovered from respiratory tract specimens are emerging confounder organisms for the laboratory diagnosis of tuberculosis worldwide. There is an urgent need for new techniques to rapidly identify mycobacteria isolated in clinical practice. Matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS) has previously been proven to effectively identify mycobacteria grown in high-concentration inocula from collections. However, a thorough evaluation of its use in routine laboratory practice has not been performed. Methodology We set up an original protocol for the MALDI-TOF MS identification of heat-inactivated mycobacteria after dissociation in Tween-20, mechanical breaking of the cell wall and protein extraction with formic acid and acetonitrile. By applying this protocol to as few as 105 colony-forming units of reference isolates of Mycobacterium tuberculosis, Mycobacterium avium, and 20 other Mycobacterium species, we obtained species-specific mass spectra for the creation of a local database. Using this database, our protocol enabled the identification by MALDI-TOF MS of 87 M. tuberculosis, 25 M. avium and 12 non-tuberculosis clinical isolates with identification scores ?2 within 2.5 hours. Conclusions Our data indicate that MALDI-TOF MS can be used as a first-line method for the routine identification of heat-inactivated mycobacteria. MALDI-TOF MS is an attractive method for implementation in clinical microbiology laboratories in both developed and developing countries.

El Khechine, Amel; Couderc, Carine; Flaudrops, Christophe; Raoult, Didier; Drancourt, Michel

2011-01-01

134

Precise identification of photosynthetic glycerolipids in microalga Tetraselmis chuii by UPLC-ESI-Q-TOF-MS.  

PubMed

Precise structural identification of photosynthetic polar glycerolipids in microalga Tetraselmis chuii has been established using Ultra Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF-MS) by direct analysis of the total lipids extract. The mass spectrometry was performed in reflective time-of-flight using electron spraying ionization in both positive and negative modes. The structural determination was based on the characteristic product ions yielded by different glycerolipids under ESI-MS/MS mode, and confirmed the molecular species by the carboxylate anions produced by glycerolipids in the negative mode. As a result, more than 40 lipid molecular species, including 11 monogalactosyldiacylglycerols (MGDG), 7 digalactosyldiacylglycerols (DGDG), 16 sulfoquinovosyldiacylglycerols (SQDG), and 9 phosphatidylglycerols (PG), were detected in Tetraselmis chuii, which had never been identified before in this microalga. Furthermore, some intact lipid molecules with hydroxylated fatty acids that could not be detected by the traditional GC-MS method were found this time, providing novel information for the photosynthetic lipidome of Tetraselmis chuii. Comparative studies on fatty acids at the sn-2 position showed that SQDG and MGDG are dominantly biosynthesized through the prokaryotic pathway, PG is a typically mixed biosynthetic pathway, while DGDG is somewhat peculiar with C14:0 and C16:0 at its sn-2 position. This method could provide a full structural profile of intact photosynthetic lipid molecular species, which may be applied to study the physiological and ecological functions of lipid by monitoring their individual changes. PMID:19093084

Li, HaiYing; Yan, XiaoJun; Xu, JiLin; Zhou, ChengXu

2008-12-18

135

Identification of protein biomarkers for schizophrenia and bipolar disorder in the postmortem prefrontal cortex using SELDI-TOF-MS ProteinChip profiling combined with MALDI-TOF-PSD-MS analysis  

Microsoft Academic Search

This paper describes the high-throughput proteomic analysis of the dorsolateral prefrontal cortex (DLPFC) from schizophrenia (SCHIZ), bipolar (BD), and normal control cohorts from the Harvard Brain Tissue Resource Center performed using ProteinChip technology based on the surface-enhanced laser desorption\\/ionization time of flight mass spectrometry (SELDI-TOF-MS). The resultant profiles were utilized in classification-tree algorithms for selection of protein biomarker peaks contributing

Svetlana I. Novikova; Fang He; Nicholas J. Cutrufello; Michael S. Lidow

2006-01-01

136

Identification and Cluster Analysis of Streptococcus pyogenes by MALDI-TOF Mass Spectrometry  

PubMed Central

Background Whole-cell matrix–assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has been successfully applied for bacterial identification and typing of many pathogens. The fast and reliable qualities of MALDI-TOF MS make it suitable for clinical diagnostics. MALDI-TOF MS for the identification and cluster analysis of Streptococcus pyogenes, however, has not been reported. The goal of our study was to evaluate this approach for the rapid identification and typing of S. pyogenes. Methods 65 S. pyogenes isolates were obtained from the hospital. The samples were prepared and MALDI-TOF MS measurements were conducted as previously reported. Identification of unknown spectra was performed via a pattern recognition algorithm with a reference spectra and a dendrogram was constructed using the statistical toolbox in Matlab 7.1 integrated in the MALDI Biotyper 2.0 software. Results For identification, 61 of 65 S. pyogenes isolates could be identified correctly by MALDI-TOF MS with BioType 2.0 when compared to biochemical identification (API Strep), with an accuracy of 93.85%. In clustering analysis, 44 of 65 isolates were in accordance with those established by M typing, with a matching rate of 67.69%. When only the M type prevalence in China was considered, 41 of 45 isolates were in agreement with M typing, with a matching rate of 91.1%. Conclusions It was here shown that MALDI-TOF MS with Soft Biotype 2.0 and its database could facilitate rapid identification of S. pyogenes. It may present an attractive alternative to traditional biochemical methods of identification. However, for classification, more isolates and advances in the MALDI-TOF MS technology are needed to improve accuracy.

Hao, Huaijie; Kang, Lin; Zheng, Yuling; Jiang, Yongqiang; Jiang, Hua

2012-01-01

137

ESI-QqTOF-MS/MS and APCI-IT-MS/MS analysis of steroid saponins from the rhizomes of Dioscorea panthaica.  

PubMed

Using high-resolution quadrupole time-of-flight mass spectrometry along with an electrospray ionization source (ESI-QqTOF-MS), accurate molecular weights of 13 steroid saponins extracted from the rhizomes of Dioscorea panthaica were acquired and the corresponding molecular formulae obtained. In order to elucidate the fragmentation pathways of steroid saponins in D. panthaica, 10 authentic samples were investigated using ESI-QqTOF-MS/MS. In addition, atmospheric pressure chemical ionization mass spectrometry combined with ion trap tandem mass spectrometry (APCI-IT-MS/MS) was used to analyze the structures of 13 steroid saponins in D. panthaica. Through the analysis of their tandem mass data, diagnostic fragment ions of the spirostanol and furostanol steroid saponins in D. panthaica were detected as m/z 271.2056 and 253.1951. In addition, four pairs of isomers were detected and the possible structures of four unknown steroid saponins in D. panthaica speculated. ESI-TOF and APCI-MS(n) have proved to be effective tools for research on fragmentation mechanism of steroid saponins and the rapid determination of native steroid saponins in extract mixture, thereby avoiding tedious derivation and separation steps. PMID:16402411

Li, Rui; Zhou, Yan; Wu, Zhijun; Ding, Lisheng

2006-01-01

138

Detection of an Extended Human Volatome with Comprehensive Two-Dimensional Gas Chromatography Time-of-Flight Mass Spectrometry  

PubMed Central

Background Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOF MS) has been proposed as a powerful new tool for multidimensional analysis of complex chemical mixtures. We investigated GCxGC-TOF MS as a new method for identifying volatile organic compounds (VOCs) in normal human breath. Methods Samples of alveolar breath VOCs and ambient room air VOC were collected with a breath collection apparatus (BCA) onto separate sorbent traps from 34 normal healthy volunteers (mean age = 40 yr, SD = 17 yr, male/female = 19/15). VOCs were separated on two serial capillary columns separated by a cryogenic modulator, and detected with TOF MS. The first and second dimension columns were non-polar and polar respectively. Results BCA collection combined with GC×GC-TOF MS analysis identified approximately 2000 different VOCs in samples of human breath, many of which have not been previously reported. The 50 VOCs with the highest alveolar gradients (abundance in breath minus abundance in ambient room air) mostly comprised benzene derivatives, acetone, methylated derivatives of alkanes, and isoprene. Conclusions Collection and analysis of breath VOCs with the BCA-GC×GC-TOF MS system extended the size of the detectable human volatile metabolome, the volatome, by an order of magnitude compared to previous reports employing one-dimensional GC-MS. The size of the human volatome has been under-estimated in the past due to coelution of VOCs in one-dimensional GC analytical systems.

Phillips, Michael; Cataneo, Renee N.; Chaturvedi, Anirudh; Kaplan, Peter D.; Libardoni, Mark; Mundada, Mayur; Patel, Urvish; Zhang, Xiang

2013-01-01

139

Reliable genotyping of short tandem repeat loci without an allelic ladder using time-of-flight mass spectrometry  

Microsoft Academic Search

DNA separations which traditionally have been performed by slab gel or capillary electrophoresis, may now be conducted via\\u000a time-of-flight mass spectrometry (TOF-MS). The advantages of using a mass spectrometry approach for short tandem repeat (STR)\\u000a characterization include a dramatic increase in both the speed of analysis and the accuracy of mass measurements. We report\\u000a here typing of the STR loci

J. M. Butler; J. Li; T. A. Shaler; J. A. Monforte; C. H. Becker

1998-01-01

140

On data analysis in PTR-TOF-MS: From raw spectra to data mining  

Microsoft Academic Search

Recently the coupling of proton transfer reaction ionization with a time-of-flight mass analyser (PTR-TOF-MS) has been proposed to realise a volatile organic compound (VOC) detector that overcomes the limitations in terms of time and mass resolution of the previous instrument based on a quadrupole mass analysers (PTR-Quad-MS). This opens new horizons for research and allows for new applications in fields

Luca Cappellin; Franco Biasioli; Pablo M. Granitto; Erna Schuhfried; Christos Soukoulis; Fabrizio Costa; Tilmann D. Märk; Flavia Gasperi

2011-01-01

141

Quantification of proteins on gold nanoparticles by combining MALDI-TOF MS and proteolysis  

NASA Astrophysics Data System (ADS)

Protein-coated nanoparticles have been used in many studies, including those related to drug delivery, disease diagnosis, therapeutics, and bioassays. The number and density of proteins on the particles’ surface are important parameters that need to be calculable in most applications. While quantification methods for two-dimensional surface-bound proteins are commonly found, only a few methods for the quantification of proteins on three-dimensional surfaces such as nanoparticles have been reported. In this paper, we report on a new method of quantifying proteins on nanoparticles using matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS). In this method, the nanoparticle-bound proteins are digested by trypsin and the resulting peptide fragments are analyzed by MALDI-TOF MS after the addition of an isotope-labeled internal standard (IS) which has the same sequence as a reference peptide of the surface-bound protein. Comparing the mass intensities between the reference peptide and the IS allows the absolute quantification of proteins on nanoparticles, because they have the same molecular milieu. As a model system, gold nanoparticles were examined using bovine serum albumin (BSA) as a coating protein. We believe that our strategy will be a useful tool that can provide researchers with quantitative information about the proteins on surfaces of three-dimensional materials.

Ju, Soomi; Yeo, Woon-Seok

2012-04-01

142

UPLC-Q-TOF-MS analysis of non-volatile migrants from new active packaging materials.  

PubMed

Ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (MS) is a useful tool in the analysis of non-volatile compounds, and the use of a quadrupole-time-of-flight (Q-TOF) mass analyzer allows a high sensitivity and accuracy when acquiring full fragment mode, providing a high assurance of correct identification of unknown compounds. In this work, UPLC-Q-TOF-MS technology has been applied to the analysis of non-volatile migrants from new active packaging materials. The materials tested were based on polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), and poly(ethylene terephthalate) (PET). The active packaging materials studied were one PP film containing a natural antioxidant, and two PP/EVOH films, two PET/EVOH films and one coextruded PP/EVOH/PP film containing natural antimicrobials. The chemical structure of several compounds was unequivocally identified. The analysis revealed the migration of some of the active substances used in the manufacture of active packaging, such as caffeine (0.07 ± 0.01 ?g/g), carvacrol (0.31 ± 0.03 ?g/g) and citral (0.20 ± 0.01 ?g/g). Unintentionally added substances were also found, such as citral reaction compounds, or citral impurities present in the raw materials. PMID:22836481

Aznar, M; Rodriguez-Lafuente, A; Alfaro, P; Nerin, C

2012-07-27

143

A calibration strategy in bioimaging trace elements in rat brain tissue by LA ICP-TOF-MS method.  

PubMed

A calibration step in an analytical procedure is often not adequately treated, although it is a very important step in the analysis. Also, the approach to the nomenclature seems to be disrespectful. In order to resolve this problem we chose a new classification based on both how the calibration dependence is reconstructed, and how the measurement data is then transformed. In this paper we discussed the steps of a developed calibration procedure in the determination of trace elements in rat brain tissues by the Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry (LA ICP-TOF-MS) method. The developed calibration procedure uses the long established calibration method - the method of standard addition - although the standard samples are in this case the rat brain tissue samples. The results show the usefulness of the procedure developed in the presented analytical problem related to the analysis of solid samples, which is where the work is original. PMID:24054579

Jurowski, Kamil; Walas, Stanislaw; Piekoszewski, Wojciech

2013-05-02

144

Intact cell mass spectrometry (ICMS) used to type methicillin-resistant Staphylococcus aureus: media effects and inter-laboratory reproducibility  

Microsoft Academic Search

Intact cell mass spectrometry (ICMS) rapidly analyses the surface composition of microorganisms providing rapid, discriminatory fingerprints for identification and subtyping of important nosocomial pathogens such as methicillin resistant Staphylocccus aureus (MRSA). In this study, ICMS using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI TOF\\/MS) was assessed for the identification and subtyping of MRSA. An intra- and inter-laboratory reproducibility study

J. Walker; A. J. Fox; V. Edwards-Jones; D. B. Gordon

2002-01-01

145

Sensitive high-resolution analysis of biological molecules by capillary zone electrophoresis coupled with reflecting time-of-flight mass spectrometry  

Microsoft Academic Search

Off-line and on-line capillary zone electrophoresis–electrospray ionization time-of-flight mass spectrometry (CZE–ESI-TOF-MS) experiments were conducted using uncoated fused-silica capillaries coupled to a reflecting TOF mass spectrometer via a gold-coated sheathless interface. Off-line and on-line experiments were performed on standard mixtures of proteins and peptides. Samples collected off-line electrokinetically in plastic vials were analyzed by standard ESI–TOF-MS at the pmol level. Sheathless

Mark E. McComb; Andrew N. Krutchinsky; Werner Ens; Kenneth G. Standing; Hélène Perreault

1998-01-01

146

Discrimination of Enterobacteriaceae and Non-fermenting Gram Negative Bacilli by MALDI-TOF Mass Spectrometry  

PubMed Central

Discrimination of Enterobacteriaceae and Non-fermenting Gram Negative Bacilli by MALDI-TOF Mass Spectrometry Matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) has proven to be an effective identification tool in medical microbiology. Discrimination to subspecies or serovar level has been found to be challenging using commercially available identification software. By forming our own reference database and using alternative analysis methods, we could reliably identify all implemented Enterobacteriaceae and non-fermenting gram negative bacilli by MALDI-TOF MS and even succeeded to distinguish Shigella sonnei from Escherichia coli (E. coli) and Salmonella enterica spp. enterica serovar Enteritidis from Salmonella enterica spp. enterica serovar Typhimurium. Furthermore, the method showed the ability to separate Enterohemorrhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC) from non-enteropathogenic E. coli.

Schaumann, Reiner; Knoop, Nicolas; Genzel, Gelimer H; Losensky, Kevin; Rosenkranz, Christiane; Stingu, Catalina S; Schellenberger, Wolfgang; Rodloff, Arne C; Eschrich, Klaus

2013-01-01

147

Discrimination of Enterobacteriaceae and Non-fermenting Gram Negative Bacilli by MALDI-TOF Mass Spectrometry.  

PubMed

Discrimination of Enterobacteriaceae and Non-fermenting Gram Negative Bacilli by MALDI-TOF Mass Spectrometry Matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) has proven to be an effective identification tool in medical microbiology. Discrimination to subspecies or serovar level has been found to be challenging using commercially available identification software. By forming our own reference database and using alternative analysis methods, we could reliably identify all implemented Enterobacteriaceae and non-fermenting gram negative bacilli by MALDI-TOF MS and even succeeded to distinguish Shigella sonnei from Escherichia coli (E. coli) and Salmonella enterica spp. enterica serovar Enteritidis from Salmonella enterica spp. enterica serovar Typhimurium. Furthermore, the method showed the ability to separate Enterohemorrhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC) from non-enteropathogenic E. coli. PMID:23919091

Schaumann, Reiner; Knoop, Nicolas; Genzel, Gelimer H; Losensky, Kevin; Rosenkranz, Christiane; Stîngu, Catalina S; Schellenberger, Wolfgang; Rodloff, Arne C; Eschrich, Klaus

2013-06-28

148

Structural deviations in poly(amidoamine) dendrimers: a MALDI-TOF MS analysis  

Microsoft Academic Search

A step-by-step synthesis\\/purification (CC, HILIC, HPLC) of poly(amidoamine) PAMAM dendrimers was performed. MALDI-TOF MS in the linear and reflectron mode was used to analyze the purified samples and byproduct samples of G0–G5 generations of the dendrimers up to the mass of 35000 Da. DHB\\/fucose was found to give the best resolution, causing the least fragmentation of the samples. The precise

J Peterson; V Allikmaa; J Subbi; T Pehk; M Lopp

2003-01-01

149

Partially oxidised organic components in urban aerosol using GCXGC-TOF\\/MS  

Microsoft Academic Search

Partially oxidised organic compounds associated with PM2.5 aerosol collected in London, England, have been analysed using direct thermal desorption coupled to compre- hensive gas chromatography-time of flight mass spectrom- etry (GCXGC-TOF\\/MS). Over 10 000 individual organic components were isolated from around 10µg of aerosol ma- terial in a single procedure and with no sample pre-treatment. Chemical functionalities observed using this

J. F. Hamilton; P. J. Webb; A. C. Lewis; J. R. Hopkins; S. Smith; P. Davy

2004-01-01

150

Rapid demonstration of diversity of sulfatide molecular species from biological materials by MALDI-TOF MS  

Microsoft Academic Search

Abstract Bycombining,the partition ,method ,for enrichment ,of sulfatides ,without ,any chromatographic procedures and the preparation method of lysosulfatides, we succeeded,in analyzing ,these ,sulfated ,glycosphingolipids from ,biological materials by MALDI-TOF MS, to reduce the complexity of mass fragmentation patterns,within,a day. Wefound,that SM4s (galactosylsulfatide) was,composed,of different,species. While ,composition ,of SM4s specifically ,depended ,on source

Mamoru Kyogashima; Keiko Tamiya-Koizumi; Takashi Ehara; Gang Li; Rui Hu; Atsushi Hara; Toshifumi Aoyama; Reiji Kannagi

2006-01-01

151

Identification of serum proteins discriminating colorectal cancer patients and healthy controls using surface-enhanced laser desorption ionisation-time of fl ight mass spectrometry  

Microsoft Academic Search

AIM: To detect the new serum biomarkers for colorectal cancer (CRC) by serum protein profiling with surface- enhanced laser desorption ionisation - time of fl ight mass spectrometry (SELDI-TOF MS). METHODS: Two independent serum sample sets were analysed separately with the ProteinChip technology (set A: 40 CRC + 49 healthy controls; set B: 37 CRC + 31 healthy controls), using

Judith YMN Engwegen; Helgi H Helgason; Annemieke Cats; Nathan Harris; Johannes MG Bonfrer; Jan HM Schellens; Jos H Beijnen

152

Evaluation of automated direct sample introduction with comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry for the screening analysis of dioxins of fish oil  

Technology Transfer Automated Retrieval System (TEKTRAN)

An automated direct sample introduction technique coupled to comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (DSI-GC×GC/TOF-MS) was applied for the development of a relatively fast and easy analytical screening method for 17 polychlorinated dibenzo-p-dioxins/dibenzo...

153

Rapid Identification of Protein Biomarkers of E. coli O157:H7 by MALDI-TOF-TOF Mass Spectrometry and Top-Down Proteomics  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have identified six protein biomarkers from two strains of E. coli O157:H7 and one non-pathogenic E. coli strain by matrix-assisted laser desorption/ionization (MALDI) time-of-flight/time-of-flight tandem mass spectrometry (TOF/TOF-MS/MS) and top-down proteomics. Mature, intact proteins were ext...

154

Potential Pitfalls in MALDI-TOF MS Analysis of Abiotically Synthesized RNA Oligonucleotides  

NASA Astrophysics Data System (ADS)

Demonstration of the abiotic polymerization of ribonucleotides under conditions consistent with conditions that may have existed on the prebiotic Earth is an important goal in "RNA world" research. Recent reports of abiotic RNA polymerization with and without catalysis rely on techniques such as HPLC, gel electrophoresis, and MALDI-TOF MS to analyze the reaction products. It is essential to understand the limitations of these techniques in order to accurately interpret the results of these analyses. In particular, techniques that rely on mass for peak identification may not be able to distinguish between a single, linear RNA oligomer and stable aggregates of smaller linear and/or cyclic RNA molecules. In the case of MALDI-TOF MS, additional complications may arise from formation of salt adducts and MALDI matrix complexes. This is especially true for abiotic RNA polymerization reactions because the concentration of longer RNA chains can be quite low and RNA, as a polyelectrolyte, is highly susceptible to adduct formation and aggregation. Here we focus on MALDI-TOF MS analysis of abiotic polymerization products of imidazole-activated AMP in the presence and absence of montmorillonite clay as a catalyst. A low molecular weight oligonucleotide standard designed for use in MALDI-TOF MS and a 3'-5' polyadenosine monophosphate reference standard were also run for comparison and calibration. Clay-catalyzed reaction products of activated GMP and UMP were also examined. The results illustrate the ambiguities associated with assignment of m/z values in MALDI mass spectra and the need for accurate calibration of mass spectra and careful sample preparation to minimize the formation of adducts and other complications arising from the MALDI process.

Burcar, Bradley T.; Cassidy, Lauren M.; Moriarty, Elizabeth M.; Joshi, Prakash C.; Coari, Kristin M.; McGown, Linda B.

2013-06-01

155

Identification of Gram-positive anaerobic cocci by MALDI-TOF mass spectrometry  

Microsoft Academic Search

Gram-positive anaerobic cocci (GPAC) are part of the commensal microbiota of humans and are a phylogenetically heterogeneous group of organisms. To evaluate the suitability of matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of GPAC, a database was constructed, using reference strains of commonly encountered GPAC and clinical isolates of which the sequence of the 16S rRNA

A. C. M. Veloo; M. Erhard; M. Welker; G. W. Welling; J. E. Degener

2011-01-01

156

Mass spectrometry-based hepcidin measurements in serum and urine: analytical aspects and clinical implications  

Microsoft Academic Search

BACKGROUND: Discovery of the central role of hepcidin in body iron regulation has shed new light on the pathophysiology of iron disorders. Information is lacking on newer analytical approaches to measure hepcidin in serum and urine. Recent reports on the measurement of urine and serum hepcidin by surface-enhanced laser-desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) necessitate analytical and clinical evaluation of

Erwin H. J. M. Kemna; Harold Tjalsma; Vladimir N. Podust; Dorine W. Swinkels

2007-01-01

157

Characterization of cyclic ?-glucans of Bradyrhizobium by MALDI-TOF mass spectrometry  

Microsoft Academic Search

Periplasmic, cyclic ?-glucans isolated from Bradyrhizobium elkanii, Bradyrhizobium liaoningense, and Bradyrhizobium yuanmingense strains have been investigated by means of Matrix-Assisted Laser Desorption\\/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS), 1D and 2D nuclear magnetic resonance (NMR), as well as standard chemical methods. These compounds are built of 10–13 d-glucose residues. The main fractions contain molecules assembled of 12 hexose units (Mw=1945.363Da). Glucose

Adam Choma; Iwona Komaniecka

2011-01-01

158

Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry  

Microsoft Academic Search

The properties of several cinnamic acid compounds used as matrices for matrix-assisted laser desorption ionization time-of-flight\\u000a mass spectrometry (MALDI-TOF MS) were investigated as standard dried droplet (DD) and vacuum sublimed preparations. The differences\\u000a between both preparation methods were analyzed with regard to matrix grain size, internal ion energy, initial velocity, analyte\\u000a intensity, and analyte incorporation depth. Some of the used

Thorsten W. Jaskolla; Michael Karas; Udo Roth; Kerstin Steinert; Christoph Menzel; Karsten Reihs

2009-01-01

159

Rapid qualitative and quantitative analyses of Asian ginseng in adulterated American ginseng preparations by UPLC/Q-TOF-MS.  

PubMed

A new method using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was developed for the rapid qualitative and quantitative analyses of Asian ginseng (Panax ginseng C.A.Meyer) in adulterated American ginseng (Panax quinquefolium L.) preparations within 2min. The method was based on the baseline chromatographic separation of isomeric compounds of ginsenoside Rf and 24(R)-pseudoginsenoside F(11), two potential chemical markers present in Panax ginseng C.A.Meyer and P. quinquefolium L. methanolic extracts. The chromatographic separation was achieved by UPLC, which used a column with 1.7microm particle packing which enabled the higher peak capacity, greater resolution, increased sensitivity and higher speed of analysis. Ginsenoside Rf and 24(R)-pseudoginsenoside F(11) were separated on baseline with retention times of 1.5 and 1.7min, respectively. Ginsenoside Rf and 24(R)-pseudoginsenoside F(11) were identified and conformed unambiguously by accurate mass measurement and their different fragmentation pathways were performed on Q-TOF-MS. Quantitative analysis was carried out under selective ion monitoring (SIM) mode. The limit of detection (LOD) of this UPLC/Q-TOF-MS analysis for ginsenoside Rf and 24(R)-pseudoginsenoside F(11) was 0.05 and 0.08ng, respectively. Ginsenoside Rf was linear over the range of 0.164-16.4ng with a correlation coefficient (R(2)) of 0.9997, while 24(R)-pseudoginsenoside F(11) was linear from 0.243 to 24.3ng with an R(2) of 0.9989. Furthermore, inter-day and intra-day precisions were obtained below 4.0% and the analytical method was fully validated. 12 batches of self-prepared adulterated samples, 11 batches of Asian ginseng, 16 batches of American ginseng and 13 batches of commercial American ginseng preparations were tested. The method developed is rapid, accurate, reliable and highly sensitive for qualitative and quantitative analyses of Asian ginseng and American ginseng. PMID:20079592

Li, Li; Luo, Guo-An; Liang, Qiong-Lin; Hu, Ping; Wang, Yi-Ming

2009-12-29

160

Direct determination of pregabalin in human urine by nonaqueous CE-TOF-MS.  

PubMed

Determination of pregabalin in urine samples was carried out by nonaqueous CE with TOF-MS via ESI, with a mixture of 10 mM ammonium formate and 0.05% acetic acid in methanol. By using TOF-MS, accurate mass information was obtained, thus causing a great improvement in qualitative ability. In order to avoid ionic suppression, urine samples dilution 1:10 was used. This was the only treatment to urine samples before the injection. Despite this dilution, the detection limit was as low as 0.03 ?g/mL for pregabalin. The method was validated with respect to accuracy, precision, and linearity, LOD, and LOQ. This method was applied to the analysis of urine samples from seven different cancer patients undergoing treatment with pregabalin. The developed method may find wide application for the routine determination of pregabalin in biological samples in order to establish a more efficient and safe dosage. PMID:23463484

Rodríguez, Juana; Castañeda, Gregorio; Muñoz, Lorena

2013-04-16

161

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry-Based Method for Discrimination between Molecular Types of Cryptococcus neoformans and Cryptococcus gattii  

PubMed Central

We evaluated the usefulness of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for Cryptococcus identification at the species and subspecies levels by using an in-house database of 25 reference cryptococcal spectra. Eighty-one out of the 82 Cryptococcus isolates (72 Cryptococcus neoformans and 10 Cryptococcus gattii) tested were correctly identified with respect to their molecular type designations. We showed that MALDI-TOF MS is a practicable alternative to conventional mycology or DNA-based methods.

Posteraro, Brunella; Vella, Antonietta; Cogliati, Massimo; De Carolis, Elena; Florio, Ada Rita; Posteraro, Patrizia; Tortorano, Anna Maria

2012-01-01

162

Isobar separation by time-of-flight mass spectrometry for low-energy radioactive ion beam facilities  

Microsoft Academic Search

A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) system for low-energy radioactive ion beam facilities has been developed, which can be used for (i) isobar separation and (ii) direct mass measurements of very short-lived nuclei with half-lives of about 1ms or longer, and (iii) for identification and diagnosis of the ion beam by mass spectrometry. The system has been designed and simulated,

Wolfgang R. Plaß; Timo Dickel; Ulrich Czok; Hans Geissel; Martin Petrick; Katrin Reinheimer; Christoph Scheidenberger; Mikhail I. Yavor

2008-01-01

163

Why is Al11B2- not a magic number in TOF-MS?  

NASA Astrophysics Data System (ADS)

Bimetallic anionic and neutral clusters, consisting of group III elements (Aln-1B1, Aln-2B2, Aln-1In1, and Inn-1Al1, n=11-14), have been theoretically investigated by density functional theory at the B3LYP/6-31G* (LanL2DZ for the In element) level. The calculated optimized equilibrium geometries and total energies of neutral and anionic clusters give a satisfactory interpretation of magic number clusters observed in time of flight mass spectra (TOF-MS). Our results show that Al11B2- is the most stable among Aln-2B2- (n=11-14) cluster anions and keeps an icosahedronlike structure, contrary to what had been suggested previously. Whether a magic number turns out in TOF-MS likely depends more on the stability of the neutral clusters than on the stability of the anions. The Al11B2 neutral cluster is less stable than Al12B2, and this is why Al11B2- does not appear as a magic number in TOF-MS. In addition, we found that icosahedral structures do not always hold for the magic cluster anions considered in the present study.

Wan, Jian; Fournier, René

2003-09-01

164

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Clinically Important Yeast Species ?  

PubMed Central

We evaluated the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of yeast species. Using Bruker Daltonics MALDI BioTyper software, we created a spectral database library with m/z ratios of 2,000 to 20,000 Da for 109 type and reference strains of yeast (44 species in 8 genera). The database was tested for accuracy by use of 194 clinical isolates (23 species in 6 genera). A total of 192 (99.0%) of the clinical isolates were identified accurately by MALDI-TOF MS. The MALDI-TOF MS-based method was found to be reproducible and accurate, with low consumable costs and minimal preparation time.

Stevenson, Lindsay G.; Drake, Steven K.; Shea, Yvonne R.; Zelazny, Adrian M.; Murray, Patrick R.

2010-01-01

165

Ion Mobility SpectrometryMass Spectrometry Performance Using Electrodynamic Ion Funnels and Elevated Drift Gas Pressures  

SciTech Connect

The ability of ion mobility spectrometry coupled with mass spectrometry (IMS-MS) to characterize biological mixtures has been illustrated over the past eight years. However, the challenges posed by the extreme complexity of many biological samples have demonstrated the need for higher resolution IMS-MS measurements. We have developed a higher resolution ESI-IMS-TOF MS by utilizing high pressure electrodynamic ion funnels at both ends of the IMS drift cell and operating the drift cell at an elevated pressure compared to a previous design. The ESI-IMS-TOF MS instrument consists of an ESI source, an hourglass ion funnel used for ion accumulation/injection into an 88 cm drift cell followed by a 10 cm ion funnel and a commercial orthogonal time-of-flight mass spectrometer providing high mass measurement accuracy. It was found that the rear (exit) ion funnel could be effectively operated as an extension of the drift cell when the DC fields were matched, allowing the instrument to have an effective drift region of 98 cm. Two differentially pumped quadrupole regions were used to couple the IMS and TOF MS to focus and minimize the ion transient time between the stages. The resolution of the instrument was evaluated at pressures ranging from 4 to12 Torr and ion mobility drift voltages of 16 V/cm (4 Torr) to 43 V/cm (12 Torr). An increase in resolution from 55 to 80 was observed from 4 to 12 Torr nitrogen drift gas with no loss in sensitivity. Given the increased usage of ion funnels prior to ion mobility separations, additional attention was directed towards the influence of drift gas on the observed ion populations trapped and transmitted using an electrodynamic ion funnel. The choice of drift gas was shown to influence the degree of ion heating and relative trapping efficiency within the ion funnel.

Baker, Erin Shammel; Clowers, Brian H.; Li, Fumin; Tang, Keqi; Tolmachev, Aleksey V.; Prior, David C.; Belov, Mikhail E.; Smith, Richard D.

2007-06-28

166

Multiplex Detection of Human Herpesviruses from Archival Specimens by Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry?  

PubMed Central

The human herpesviruses are involved in a variety of diseases. Large-scale evaluation of the clinical and epidemiological importance of different herpesviruses requires high-throughput methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a method that has a multiplex capacity enabling simultaneous detection of several viruses in a single sample. PCR-based methods for the multiplex detection of all known human herpesviruses were developed on the MALDI-TOF MS system. A variety of 882 archival samples, including bronchoalveolar lavage, conjunctival fluid, sore secretion, blister material, plasma, serum, and urine, analyzed for herpesviruses using PCR-based reference methods, were used to evaluate the MALDI-TOF MS method. The overall concordance rate between the MALDI-TOF MS method and the reference methods was 95.6% (? = 0.90). In summary, the MALDI-TOF MS method is well suited for large-scale detection of all known human herpesviruses in a wide variety of archival biological specimens.

Sjoholm, Malin I. L.; Dillner, Joakim; Carlson, Joyce

2008-01-01

167

Matrix-assisted laser desorption ionization-time of flight mass spectrometry: a fundamental shift in the routine practice of clinical microbiology.  

PubMed

Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the "nuts and bolts" of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care. PMID:23824373

Clark, Andrew E; Kaleta, Erin J; Arora, Amit; Wolk, Donna M

2013-07-01

168

High Throughput Enzyme Inhibitor Screening by Functionalized Magnetic Carbonaceous Microspheres and Graphene Oxide-Based MALDI-TOF-MS  

NASA Astrophysics Data System (ADS)

In this work, a high throughput methodology for screening enzyme inhibitors has been demonstrated by combining enzyme immobilized magnetic carbonaceous microspheres and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with grapheme oxide as matrix. First, model enzyme acetylcholinesterase (AChE) was immobilized onto the 3-glycidoxypropyltrimethoxysilane (GLYMO)-modified magnetic carbonaceous (MC) microspheres, displaying a high enzyme activity and stability, and also facilitating the separation of enzyme from substrate and product. The efficiency of immobilized AChE was monitored by biochemical assay, which was carried out by mixing enzyme-immobilized MC microspheres with model substrate acetylcholine (ACh), and subsequent quantitative determination of substrate ACh and product choline using graphene oxide-based MALDI-TOF-MS with no background inference. The limit of detection (LOD) for ACh was 0.25 fmol/?L, and excellent linearity (R2 = 0.9998) was maintained over the range of 0.5 and 250 fmol/?L. Choline was quantified over the range of 0.05 and 15 pmol/?L, also with excellent linearity (R2 = 0.9994) and low LOD (0.15 fmol/?L). Good accuracy and precision were obtained for all concentrations within the range of the standard curves. All together, eight compounds (four known AChE inhibitors and four control chemical compounds with no AChE inhibit effect) were tested with our promoted methodology, and the obtained results demonstrated that our high throughput screening methodology could be a great help to the routine enzyme inhibitor screening.

Liu, Yang; Li, Yan; Liu, Junyan; Deng, Chunhui; Zhang, Xiangmin

2011-12-01

169

Biochemical assays of immobilized oligonucleotides with mass spectrometry.  

PubMed

This paper reports the use of mass spectrometry to characterize oligonucleotides immobilized to the surfaces of biochips. Biotinylated oligonucleotides were immobilized to self-assembled monolayers that present a streptavidin layer and then treated with a complementary strand to present short duplexes. Treatment of the surface with 5-methoxysalicylic acid and ammonium citrate matrix allows the individual oligonucleotides to be observed by matrix-assisted laser desorption/iozation and time-of-flight mass spectrometry (MALDI-TOF MS). Examples are shown wherein this method is applied to assays of hybridization, of cleavage by a deoxyribozyme, of a dephosphorylation reaction, and of the adducts formed on treatment of DNA with cis-platin. This work provides an early example of the application of mass spectrometry to DNA biochips and may substantially expand the applications of the now common oligonucleotide arrays. PMID:18407676

Tsubery, Haim; Mrksich, Milan

2008-04-12

170

Evaluation of the combination of bead technology with SELDI-TOF-MS and 2-D DIGE for detection of plasma proteins.  

PubMed

Today biomarker discovery is one of the most active aspects of proteomic investigations. However, the wide dynamic range of plasma proteins makes the analysis very challenging because high abundance proteins tend to mask those of lower abundance. Using a large bead-based library of combinatorial peptide ligands (Equalizer beads or ProteoMiner), the dynamic range of the protein concentration is compressed, the high abundance proteins present in the sample are reduced and the low abundance proteins are enriched, while retaining representatives of all proteins within the sample. In the present study, the combination of beads with surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS) and two-dimensional differential gel electrophoresis (2-D DIGE) technology were evaluated considering efficiency, reproducibility, sensitivity, and compatibility. The bead technology is easily compatible with both SELDI-TOF-MS and 2-D DIGE and the samples can be analyzed directly without any processing of the sample. The use of the beads prior SELDI-TOF-MS and 2-D DIGE enabled detection of many new protein spots/peaks and increased resolution and improved intensity of low abundance proteins in a reproducible fashion compared with the depletion technique. Several proteins have been identified by the combination of beads, 2-D DIGE and MS for example different kinds of complement factors and cytoskeletal proteins. Our data suggest that integration of the bead technology with our current proteomic technologies will enhance the possibility to deliver new peptide/protein biomarker candidates in our projects. PMID:18690747

Sihlbom, Carina; Kanmert, Ida; Bahr, Helena von; Davidsson, Pia

2008-08-09

171

LC/TOF-MS Identification of Organic Components in Cloud and Fog Water Samples  

NASA Astrophysics Data System (ADS)

The nature and identity of organic compounds in cloud and fog droplets are not well understood. Approximately 80 percent of the total organic carbon remains unidentified due to several confounding factors. Traditionally, many of the organic compound analyses have been accomplished by the use of gas chromatography (GC) / mass spectrometry (MS) methods. These methods require analytes to be extracted from water and introduced into the GC by the use of organic solvents. Extraction efficiencies of the water- soluble organic components vary widely depending upon molecular size and polarity. Additionally, many polar compounds are thermally labile and require derivatization to make them more amenable for GC/MS analysis. Liquid chromatography (LC) methods which allow for sample introduction in water have also been used widely for organic analyses. However, commonly used detection methods such as conductivity, UV absorbance, and fluorescence limit the identification of organic components based on detection specific associated physical properties. Recently, electrospray ionization has allowed for MS detection to be paired with LC. There exist several types of MS each with their own specific advantages and disadvantages. In this study, we used LC with accurate mass time of flight (TOF) MS. The distinct advantage of accurate mass TOF is that it may be used to identify unknown organic compounds. Here we present results from our search for novel organic components (including organic nitrogen and organosulfates) in a variety of cloud and fog water samples from polluted and rural environments. These results are paired with established measurement methods for liquid water content, pH, and concentrations of total organic carbon (TOC), dissolved organic carbon (DOC), carbohydrates, formaldehyde, low molecular weight organic acids, carbonyls, and organic nitrogen.

Rinehart, L. R.; Shen, X.; Collett, J. L.

2006-12-01

172

Robust Hepatitis B Virus Genotyping by Mass Spectrometry ?  

PubMed Central

Genotyping of hepatitis B virus (HBV) is important for tracking HBV infections, prognosticating the development of severe liver disease, and predicting outcomes of therapy. Current genotyping methods can be laborious and costly and rely on subjective data interpretation. To identify less expensive but equally reliable alternatives, we compared “gold standard” sequencing to a novel mass spectrometry approach. Sera from individuals with acute or chronic HBV infection (n = 756), representing all genotypes, were used to PCR amplify the HBV S gene. All amplicons were subjected to base-specific cleavage and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The resulting mass peak patterns were used to identify HBV genotype by automated comparison to peak patterns simulated from reference sets of HBV sequences of known genotypes. The MALDI-TOF MS data and phylogenetic analysis of HBV sequences produced completely concordant results. Several parameters such as genetic relatedness of tested HBV variants to the reference set, chronic infections, and the quality of PCR products can lower the MS score but never affected the accuracy of the genotype call. This new streamlined MS-based method provides for rapid and accurate HBV genotyping, produces automated data reports, and is therefore suitable for routine use in diagnostic settings.

Ganova-Raeva, L.; Ramachandran, S.; Honisch, C.; Forbi, J. C.; Zhai, X.; Khudyakov, Y.

2010-01-01

173

Characterization of the microheterogeneity of transthyretin in plasma and urine using SELDI-TOF-MS immunoassay  

PubMed Central

Background It has been shown that transthyretin (TTR) exists in different molecular variants. Besides point mutations associated with different diseases such as amyloidosis, other posttranslational modifications occur that might be of diagnostic interest. Results TTR levels as determined by ELISA in plasma and urine of healthy individuals were 489 ± 155 ?g/ml plasma and 46 ± 24 ng/g creatinine, respectively. Average levels in urine of pregnant women were 45 ± 65 ?g/g creatinine. The molecular heterogeneity of TTR was analyzed using a high-throughput mass spectrometric immunoassay system. TTR was extracted from plasma or urine onto an antibody-coated (via protein A) affinity chip surface (PS20) using the surface-enhanced laser desorption/ionization (SELDI) technique. Subsequently samples were subjected to time-of-flight mass spectrometry (TOF-MS). In healthy individuals, TTR in plasma occurred rather consistently in two variants of 13732 ± 12 and 13851 ± 9 Da for the native and S-cysteinylated forms and at a smaller signal of 14043 ± 17 Da for the S-glutathionylated form. In urine of pregnant women, various signals were observed with a dominant signal at 13736 ± 10 Da and a varying number of smaller immunoreactive fragments. These fragments are possibly the consequence of metabolism in plasma or kidney. Conclusion This chip-based approach represents a rapid and accurate method to characterize the molecular variants of TTR including protein or peptide fragments which are either related to TTR or have resulted from its catabolism. These molecular variants may be of diagnostic importance as alternative or novel biomarkers due to their predominant relation to the TTR metabolism both in healthy and diseased individuals.

Schweigert, Florian J; Wirth, Kerstin; Raila, Jens

2004-01-01

174

The Use of Principal Component Analysis in MALDI-TOF MS: a Powerful Tool for Establishing a Mini-optimized Proteomic Profile  

PubMed Central

Background Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technology has been applied to the exploration of biomarkers for early cancer diagnosis, but more effort is required to identify a single sensitive and specific biomarker. For early diagnosis, a proteomic profile is the gold standard, but inconvenient for clinical use since the profile peaks are quantitative. It would therefore be helpful to find a minimized profile, comprising fewer peaks than the original using an existing algorithm and compare it with other traditional statistical methods. Methods In the present study, principal component analysis (PCA) in the ClinProt-Tools of MALDI-TOF MS was used to establish a mini-optimized proteomic profile from gastric cancer patients and healthy controls, and the result was compared with t-test and Flexanalysis software. Results Eight peaks were selected as the mini-optimized proteomic profile to help differentiate between gastric cancer patients and healthy controls. The peaks at m/z 4212 were regarded as the most important peak by the PCA algorithm. The peaks at m/z 1866 and 2863 were identified as deriving from complement component C3 and apolipoprotein A1, respectively. Conclusions PCA enabled us to identify a mini-optimized profile consisting of significantly differentiating peaks and offered the clue for further research.

Shao, Changli; Tian, Yaping; Dong, Zhennan; Gao, Jing; Gao, Yanhong; Jia, Xingwang; Guo, Guanghong; Wen, Xinyu; Jiang, Chaoguang; Zhang, Xueji

2011-01-01

175

Evaluation of different extraction approaches for the determination of phenolic compounds and their metabolites in plasma by nanoLC-ESI-TOF-MS.  

PubMed

Sample preparation is an important step for the determination of phenolic compounds in biological samples. Different extraction methods have been tested to determine phenolic compounds and their metabolites in plasma by nano-liquid chromatography coupled to electrospray ionisation-time-of-flight mass spectrometry (nanoLC-ESI-TOF-MS). The sample treatment optimisation was performed using commercial foetal bovine serum spiked with representative phenolic standards, namely naringenin, luteolin, verbascoside, apigenin, rutin, syringic acid and catechin. Different protein-precipitation conditions were evaluated as well as enzymatic digestion with trypsin and solid-phase extraction using different phases such as C-18, ABN and ENV+, working at different pH values. The optimum extraction procedure consisted of a previous protein-precipitation step using HCl 200 mmol/L in methanol for 2.5 h at 50 °C followed by a solid-phase extraction using C-18 cartridges at pH 2.5. This procedure was finally applied to the plasma of rats overfed with a phenolic-rich Lippia citriodora extract. These samples were analysed by nanoLC-ESI-TOF-MS, enabling the identification of five compounds previously found in the administered L. citriodora extract and one metabolite. PMID:23064706

Quirantes-Piné, R; Verardo, V; Arráez-Román, D; Fernández-Arroyo, S; Micol, V; Caboni, M F; Segura-Carretero, A; Fernández-Gutiérrez, A

2012-10-13

176

The Effect of Culture Conditions on Microorganism Identification by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry  

SciTech Connect

Abstract Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to identify bacteria based upon protein signatures. This research shows that while some different proteins are produced by vegetative bacteria when they are cultured in different growth media, positive identification with MALDI-TOF MS is still possible with the protocol established at Pacific Northwest National Laboratory (PNNL)(11). A core set of small proteins remain constant under at least four different culture media conditions including minimal medium -M9, rich media - tryptic soy broth (TSB) or Luria-Bertani (LB) broth and blood agar plates such that analysis of the intact cells by matrix-assisted laser desorption/ionization mass spectrometry allows for consistent identification.

Valentine, Nancy B.; Wunschel, Sharon C.; Wunschel, David S.; Petersen, Catherine E.; Wahl, Karen L.

2005-01-01

177

Endosulfan-induced biomarkers in Japanese rice fish (Oryzias latipes) analyzed by SELDI-TOF-MS.  

PubMed

The objective of this study was to find and validate estrogen-related biomarkers from plasma proteins in Oryzias latipes after exposure to an estrogen disrupting compound, ?-endosulfan. The acute toxicity of ?-endosulfan on O. latipes after 96 h of exposure was 13.72, 16.18, and 22.18 ?g L(-1) for the LC10, LC20, and LC50 values, respectively. To confirm estrogenic disturbance by ?-endosulfan, the expression level of vitellogenin in the liver of male fishes was measured at the LC10 value, and it was found to be significantly different from the reference group, confirming the estrogenic effect of endosulfan in this concentration range. Proteinchip® array techniques using a weak cation exchange (CM10) and a strong anion exchange proteinchip (Q10) in conjunction with surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) were used to determine plasma proteins of O. latipes differently expressed in response to endosulfan exposure at LC10 and LC20 concentrations. Analysis of protein profiling of the male fish exposed to ?-endosulfan detected 48 significantly different protein peaks and the proteins at m/z 2819, 8462, 8860, and 9462 were significantly different (p<0.05). The protein peaks at m/z 2819, 8860, and 9462 were up-regulated and the peak at m/z 8462 was down-regulated. Therefore, these four differentially expressed proteins could be used as biomarkers to rapidly determine a possible risk of endosulfan on aquatic ecosystems, although these are not necessarily produced as a result of endocrine disruption. PMID:23630446

Lee, Sung-Eun; Young-Woong, Choi; Mo, Hyoung-ho; Son, Jino; Park, Kyeonghun; Cho, Kijong

2013-04-13

178

Proteomic approach based on MALDI-TOF MS to detect powdered milk in fresh cow's milk.  

PubMed

Milk and cheese are expensive foodstuffs, and their consumption is spread among the population because of their high nutritional value; for this reason they are often subjected to adulterations. Among the common illegal practices, the addition of powdered derivatives seems very difficult to detect because the adulterant materials have almost the same chemical composition of liquid milk. However, the high temperatures (180-200 °C) used for milk powder production could imply the occurrence of some protein modifications (e.g., glycation, lactosylation, oxidation, deamidation, dehydration). The modified proteins or peptides could then be used as markers for the presence of powdered milk. In this work, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to analyze tryptic digests relevant to samples of raw liquid (without heat treatment), commercial liquid, and powdered cow's milk. Samples were subjected to two-dimensional gel electrophoresis (2-DE); differences among liquid and powder milk were detected at this stage and eventually confirmed by MALDI analysis of the in gel digested proteins. Some diagnostic peptides of powdered milk, attributed to modified whey proteins and/or caseins, were identified. Then, a faster procedure was optimized, consisting of the separation of caseins from milk whey and the subsequent in-solution digestion of the two fractions, with the advantage of obtaining almost the same information in a limited amount of time. Finally, analyses were carried out with the fast procedure on liquid milk samples adulterated with powdered milk at different percentages, and diagnostic peptides were detected down to 1% of adulteration level. PMID:22931122

Calvano, Cosima Damiana; Monopoli, Antonio; Loizzo, Pasqua; Faccia, Michele; Zambonin, Carlo

2012-09-10

179

The mass spectral density in quantitative time-of-flight mass spectrometry of polymers  

NASA Astrophysics Data System (ADS)

Time-of-flight mass spectrometry (TOF-MS) is being increasingly used for the study of polymers, for example to obtain the distribution of molecular masses for polymer samples. Serious efforts have also been underway to use TOF-MS for DNA sequencing. In TOF-MS the data is obtained in the form of a time-series that represents the distribution in arrival times of ions of various m/z ratios. This time-series data is then converted to a "mass-spectrum" via a coordinate transformation from the arrival time (t) to the corresponding mass-to-charge ratio (m/z = const. t^2). In this transformation, it is important to keep in mind that spectra are distributions, or densities of weight +1, and thus do not transform as functions. To obtain the mass-spectral density, it is necessary to include a multiplicative factor of ?m/z. Common commercial instruments do not take this factor into account. Dropping this factor has no effect on qualitative analysis (detection) or local quantitative measurements, since S/N or signal-to-baseline ratios are unaffected for peaks with small dispersions. However, there are serious consequences for general quantitative analyses. In DNA sequencing applications, loss of signal intensity is in part attributed to multiple charging; however, since the ?m/z factor is not taken into account, this conclusion is based on an overestimate (by a factor of ?z) of the relative amount of the multiply charged species. In the study of polymers, the normalized dispersion is underestimated by approximately (M_w/Mn -1)/2. In terms of M_w/Mn itself, for example, a M_w/M_n=1.5 calculated without the ?m factor corresponds in fact to a M_w/M_n=1.88.

Tate, Ranjeet S.; Ebeling, Dan; Smith, Lloyd M.

2001-03-01

180

Monitoring of peptide acylation inside degrading PLGA microspheres by capillary electrophoresis and MALDI-TOF mass spectrometry  

Microsoft Academic Search

The purpose of this research was to assess the acylation reactions of peptides, salmon calcitonin (sCT), human parathyroid hormone 1–34 (hPTH1–34) and leuprolide, in poly(lactic-co-glycolic acid) (PLGA) microspheres. Capillary electrophoresis (CE) and matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used for determining and monitoring peptide acylation and quantitating acylation products in the degrading PLGA microspheres. In the degrading

Dong Hee Na; Yu Seok Youn; Sang Deuk Lee; Mi-Won Son; Won-Bae Kim; Patrick P. DeLuca; Kang Choon Lee

2003-01-01

181

Rapid Identification and Typing of Listeria Species by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

Microsoft Academic Search

Listeria monocytogenes is a food-borne pathogen that is the causative agent of human listeriosis, an oppor- tunistic infection that primarily infects pregnant women and immunologically compromised individuals. Rapid, accurate discrimination between Listeria strains is essential for appropriate therapeutic management and timely intervention for infection control. A rapid method involving matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) that

Sukhadeo B. Barbuddhe; Thomas Maier; Gerold Schwarz; Markus Kostrzewa; Herbert Hof; Eugen Domann; Trinad Chakraborty; Torsten Hain

2008-01-01

182

Establishing drug resistance in microorganisms by mass spectrometry.  

PubMed

A rapid method to determine drug resistance in bacteria based on mass spectrometry is presented. In it, a mass spectrum of an intact microorganism grown in drug-containing stable isotope-labeled media is compared with a mass spectrum of the intact microorganism grown in non-labeled media without the drug present. Drug resistance is determined by predicting characteristic mass shifts of one or more microorganism biomarkers using bioinformatics algorithms. Observing such characteristic mass shifts indicates that the microorganism is viable even in the presence of the drug, thus incorporating the isotopic label into characteristic biomarker molecules. The performance of the method is illustrated on the example of intact E. coli, grown in control (unlabeled) and (13)C-labeled media, and analyzed by MALDI TOF MS. Algorithms for data analysis are presented as well. PMID:23568030

Demirev, Plamen A; Hagan, Nathan S; Antoine, Miquel D; Lin, Jeffrey S; Feldman, Andrew B

2013-04-09

183

Derivatized mesoporous silica beads for MALDI-TOF MS profiling of human plasma and urine.  

PubMed

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a promising tool for large-scale screening of body fluids for the early detection of human diseases. Proteins, peptides, and metabolites present in cells, tissues, or in body fluids constitute the molecular signatures of individuals. The design and generation of material-based platforms for capturing molecular signatures from body fluids has gained increasing interest in recent years. Highly selective materials are attractive candidates for a wide range of applications in biofluid proteomics. We have therefore developed a procedure based on mesoporous silica particles for the selective binding and enrichment of low molecular weight plasma/serum proteins by MALDI MS analysis ( Terracciano, R., Gaspari, M., Testa, F., Pasqua, L., Cuda G., Tagliaferri, P., Cheng, M. C., Nijdam, A. J., Petricoin, E. F., Liotta, L. A., Ferrari, M., and Venuta, S. ( 2006 ) Selective binding and enrichment for low-molecular weight biomarker molecules in human plasma after exposure to nanoporous silica particles . Proteomics 6, 3243-3250 ). Mesoporous silica beads (MSB) are able to harvest peptides from plasma and serum by means of nanosized porous channels with high surface area, while excluding large size proteins. Moreover, the absorption properties can be modified since the pore walls can be functionalized with different chemical species due to the high concentration of silanol groups at the surface. In this study, we performed derivatization of MSB with different functionalities, and we evaluated the derivatized materials for plasma and urine peptidomic profiling. Aminopropyl, N-(2-aminoethyl)-3-aminopropyl, and N,N,N' tris-carboxymethyl ethylene diamine, have been introduced onto the mesoporous silica surfaces in order to modulate selective peptide enrichment. We also explored various experimental conditions in order to optimize the performance of chemically modified MSB in the peptide profiling of human plasma and urine. These new derivatized mesoporous surfaces, in addition to the previous nonderivatized MSB, constitute an extended and reliable platform of five distinct chromatographic phases with defined surface functionality and porosity. Several plasma and urine peptides were extracted from derivatized MSB and then profiled by MALDI-TOF MS. The reproducibility of sample preparation by different functionalized beads was evaluated via three replicate analyses of plasma and urine samples. Lower coefficients of variation in the mass values and peak intensities resulted for plasma in comparison to those of urine samples; nevertheless, these where satisfactory for diagnostic purposes. For human urine, a linear correlation was found between spiked peptide concentrations and their peak areas (R(2) > 0.98) with a limit of detection in the low-nanogram per milliliter range, thus confirming the high sensitivity of the methodology, previously demonstrated for human plasma. Different panels of peptide repertoires have thus been collected from highly porous substrates chemically conjugated with different functional groups, and these may be used in biomarker discovery for disease diagnosis. PMID:19338374

Terracciano, Rosa; Pasqua, Luigi; Casadonte, Francesca; Frascà, Stella; Preianò, Mariaimmacolata; Falcone, Daniela; Savino, Rocco

2009-05-20

184

Identification and subtyping of clinically relevant human and ruminant mycoplasmas by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) recently emerged as a technology for the identification of bacteria. In this study, we aimed to evaluate its applicability to human and ruminant mycoplasmal identification, which can be demanding and time-consuming when using phenotypic or molecular methods. In addition, MALDI-TOF MS was tested as a subtyping tool for certain species. A total of 29 main spectra (MSP) from 10 human and 13 ruminant mycoplasma (sub)species were included in a mycoplasma MSP database to complete the Bruker MALDI Biotyper database. After broth culture and protein extraction, MALDI-TOF MS was applied for the identification of 119 human and 143 ruminant clinical isolates that were previously identified by antigenic or molecular methods and for subcultures of 73 ruminant clinical specimens that potentially contained several mycoplasma species. MALDI-TOF MS resulted in accurate (sub)species-level identification with a score of ?1.700 for 96% (251/262) of the isolates. The phylogenetically closest (sub)species were unequivocally distinguished. Although mixtures of the strains were reliably detected up to a certain cellular ratio, only the predominant species was identified from the cultures of polymicrobial clinical specimens. For typing purposes, MALDI-TOF MS proved to cluster Mycoplasma bovis and Mycoplasma agalactiae isolates by their year of isolation and genome profiles, respectively, and Mycoplasma pneumoniae isolates by their adhesin P1 type. In conclusion, MALDI-TOF MS is a rapid, reliable, and cost-effective method for the routine identification of high-density growing mycoplasmal species and shows promising prospects for its capacity for strain typing. PMID:23903545

Pereyre, S; Tardy, F; Renaudin, H; Cauvin, E; Del Prá Netto Machado, L; Tricot, A; Benoit, F; Treilles, M; Bébéar, C

2013-07-31

185

Optimizing identification of clinically relevant Gram-positive organisms by use of the Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry system.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) can be used as a method for the rapid identification of microorganisms. This study evaluated the Bruker Biotyper (MALDI-TOF MS) system for the identification of clinically relevant Gram-positive organisms. We tested 239 aerobic Gram-positive organisms isolated from clinical specimens. We evaluated 4 direct-smear methods, including "heavy" (H) and "light" (L) smears, with and without a 1-?l direct formic acid (FA) overlay. The quality measure assigned to a MALDI-TOF MS identification is a numerical value or "score." We found that a heavy smear with a formic acid overlay (H+FA) produced optimal MALDI-TOF MS identification scores and the highest percentage of correctly identified organisms. Using a score of ?2.0, we identified 183 of the 239 isolates (76.6%) to the genus level, and of the 181 isolates resolved to the species level, 141 isolates (77.9%) were correctly identified. To maximize the number of correct identifications while minimizing misidentifications, the data were analyzed using a score of ?1.7 for genus- and species-level identification. Using this score, 220 of the 239 isolates (92.1%) were identified to the genus level, and of the 181 isolates resolved to the species level, 167 isolates (92.2%) could be assigned an accurate species identification. We also evaluated a subset of isolates for preanalytic factors that might influence MALDI-TOF MS identification. Frequent subcultures increased the number of unidentified isolates. Incubation temperatures and subcultures of the media did not alter the rate of identification. These data define the ideal bacterial preparation, identification score, and medium conditions for optimal identification of Gram-positive bacteria by use of MALDI-TOF MS. PMID:23426925

McElvania Tekippe, Erin; Shuey, Sunni; Winkler, David W; Butler, Meghan A; Burnham, Carey-Ann D

2013-02-20

186

N-(1-Naphthyl) Ethylenediamine Dinitrate: A New Matrix for Negative Ion MALDI-TOF MS Analysis of Small Molecules  

NASA Astrophysics Data System (ADS)

An organic salt, N-(1-naphthyl) ethylenediamine dinitrate (NEDN), with rationally designed properties of a strong UV absorbing chromophore, hydrogen binding and nitrate anion donors, has been employed as a matrix to analyze small molecules ( m/z < 1000) such as oligosaccharides, peptides, metabolites and explosives using negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Compared with conventional matrixes such as ?-cyano-4-hydroxycinnamic acid (CCA) and 2,5-dihydroxybenzoic acid (DHB), NEDN provides a significant improvement in detection sensitivity and yields very few matrix-associated fragment and cluster ions interfering with MS analysis. For low-molecular-weight saccharides, the lowest detection limit achieved ranges from 500 amol to 5 pmol, depending on the molecular weight and the structure of the analytes. Additionally, the mass spectra in the lower mass range ( m/z < 200) consist of only nitrate and nitric acid cluster ions, making the matrix particularly useful for structural identification of oligosaccharides by post-source decay (PSD) MALDI-MS. Such a characteristic is illustrated by using maltoheptaose as a model system. This work demonstrates that NEDN is a novel negative ion-mode matrix for MALDI-MS analysis of small molecules with nitrate anion attachment.

Chen, Rui; Chen, Suming; Xiong, Caiqiao; Ding, Xunlei; Wu, Chih-Che; Chang, Huan-Cheng; Xiong, Shaoxiang; Nie, Zongxiu

2012-09-01

187

Fungal pigments inhibit the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of darkly pigmented fungi.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to discriminate moniliaceous fungal species; however, darkly pigmented fungi yield poor fingerprint mass spectra that contain few peaks of low relative abundance. In this study, the effect of dark fungal pigments on the observed MALDI mass spectra was investigated. Peptide and protein samples containing varying concentrations of synthetic melanin or fungal pigments extracted from Aspergillus niger were analyzed by MALDI-TOF and MALDI-qTOF (quadrupole TOF) MS. Signal suppression was observed in samples containing greater than 250ng/?l pigment. Microscopic examination of the MALDI sample deposit was usually heterogeneous, with regions of high pigment concentration appearing as black. Acquisition of MALDI mass spectra from these darkly pigmented regions of the sample deposit yielded poor or no [M+H](+) ion signal. In contrast, nonpigmented regions within the sample deposit and hyphal negative control extracts of A. niger were not inhibited. This study demonstrated that dark fungal pigments inhibited the desorption/ionization process during MALDI-MS; however, these fungi may be successfully analyzed by MALDI-TOF MS when culture methods that suppress pigment expression are used. The addition of tricyclazole to the fungal growth media blocks fungal melanin synthesis and results in less melanized fungi that may be analyzed by MALDI-TOF MS. PMID:21094115

Buskirk, Amanda D; Hettick, Justin M; Chipinda, Itai; Law, Brandon F; Siegel, Paul D; Slaven, James E; Green, Brett J; Beezhold, Donald H

2010-11-19

188

Analysis of Organics in Clays with Laser Time of Flight Mass Spectrometry  

NASA Astrophysics Data System (ADS)

A range of clays have been detected on the surface of Mars lending support to the presence of an early water-rich epoch dramatically different than the planet’s current environment. The potential preservation of ancient chemical habitability signatures in clays could drive future missions such as NASA’s Mid-Range Rover to such “phyllosilicate regions”. Various laboratory studies have focused on the incorporation and preservation of organic material, such as amino acids, nucleobases, and more complex biomarkers, in terrestrial clays. Laser-based time-of-flight mass spectrometry (TOF-MS) may be one technique capable of conducting such analyses in situ without extensive sample preparation. We are testing the capabilities of a miniature TOF-MS to analyze clay minerals and any associated organic molecules. We have recorded baseline mass spectra of terrestrial source clays SWy-2 (Na-Montmorillonite), KGa-1b (Kaolinite), and SAz-2 (Ca-Montmorillonite) obtained via the Source Clays Project of the Clay Minerals Society. Here we will present the first results of our measurements of the selected clays in their natural state, as well as spiked with an amino acids standard. The focus of this presentation will be both on the absorption of the amino acids as well an on the detection capability of the TOF-MS instrument.

ten Kate, I. L.; Getty, S.; Cornish, T.; Brinckerhoff, W. B.

2009-12-01

189

A laser desorption ionization time-of-flight mass spectrometry investigation into triacylglycerols oxidation during thermal stressing of edible oils.  

PubMed

Laser desorption ionization time-of-flight mass spectrometry (LDI-TOF MS) was used to characterize olive and sunflower oils before and after thermally assisted oxidation in order to develop a rapid fingerprinting method for oil that contains unchanged and oxidized components. No matrix was used to assist laser desorption, and simplified mass spectra were obtained in the mass range of interest (m/z 500-1000), where triacyl- and diacylglycerol ions were observed. Sample preparation was reduced to dissolving oil in chloroform saturated with NaCl. Sodiated triacylglycerols (TAGs), their epoxy/hydroxy and hydroperoxy derivatives, as well as TAGs with shortened chain fatty acids (beta-scission products) were clearly observed in the spectra. LDI-TOF MS rapidly provides semiquantitative information about the oxidation level of edible oil, and thus represents a very useful quality control tool. PMID:17541564

Calvano, Cosima Damiana; Aresta, Antonella; Palmisano, Francesco; Zambonin, Carlo G

2007-05-31

190

Matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid identification of tick vectors.  

PubMed

A method for rapid species identification of ticks may help clinicians predict the disease outcomes of patients with tick bites and may inform the decision as to whether to administer postexposure prophylactic antibiotic treatment. We aimed to establish a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectrum database based on the analysis of the legs of six tick vectors: Amblyomma variegatum, Rhipicephalus sanguineus, Hyalomma marginatum rufipes, Ixodes ricinus, Dermacentor marginatus, and Dermacentor reticulatus. A blind test was performed on a trial set of ticks to identify specimens of each species. Subsequently, we used MALDI-TOF MS to identify ticks obtained from the wild or removed from patients. The latter tick samples were also identified by 12S ribosomal DNA (rDNA) sequencing and were tested for bacterial infections. Ticks obtained from the wild or removed from patients (R. sanguineus, I. ricinus, and D. marginatus) were accurately identified using MALDI-TOF MS, with the exception of those ticks for which no spectra were available in the database. Furthermore, one damaged specimen was correctly identified as I. ricinus, a vector of Lyme disease, using MALDI-TOF MS only. Six of the 14 ticks removed from patients were found to be infected by pathogens that included Rickettsia, Anaplasma, and Borrelia spp. MALDI-TOF MS appears to be an effective tool for the rapid identification of tick vectors that requires no previous expertise in tick identification. The benefits for clinicians include the more targeted surveillance of patients for symptoms of potentially transmitted diseases and the ability to make more informed decisions as to whether to administer postexposure prophylactic treatment. PMID:23224087

Yssouf, Amina; Flaudrops, Christophe; Drali, Rezak; Kernif, Tahar; Socolovschi, Cristina; Berenger, Jean-Michel; Raoult, Didier; Parola, Philippe

2012-12-05

191

Ni speciation in tea infusions by monolithic chromatography--ICP-MS and Q-TOF-MS.  

PubMed

For humans, Ni is not considered to be an essential trace element. Its compounds, at levels present in foodstuffs and drinks, are generally considered to be safe for consumption, but for individuals who already suffer from contact allergy to Ni and may be subject to develop systemic reactions from its dietary ingestion, dietary exposure to Ni must be kept under control. Being the second most popular beverage, tea is a potential source of dietary Ni. Present knowledge on its speciation in tea infusions is poor. Therefore, complete speciation analysis, consisting of separation by liquid chromatography using a weak CIM DEAE-1 monolithic column, "on-line" detection by inductively coupled plasma mass spectrometry (ICP-MS) and "off-line" identification of ligands by hybrid quadrupole time-of-flight mass spectrometry (Q-TOF MS), was implemented for the first time to study Ni speciation in tea infusions. Total concentrations of Ni in dry leaves of white, green, oolong and black tea (Camellia sinensis) and flowers of herbal chamomile (Matricaria chamomilla) and hibiscus (Hibiscus sabdariffa) tea were determined after microwave digestion by ICP-MS. They lay between 1.21 and 14.4 mg kg(-1). Good agreement between the determined and the certified values of the Ni content in the standard reference material SRM 1573a tomato leaves confirmed the accuracy of the total Ni determination. During the infusion process, up to 85 % of Ni was extracted from tea leaves or flowers. Separation of Ni species was completed in 10 min by applying aqueous linear gradient elution with 0.6 mol L(-1) NH(4)NO(3). Ni was found to be present in the chromatographic fraction in which quinic acid was identified by Q-TOF in all the tea infusions analysed, which had pH values between 5.6 and 6.0. The only exception was the infusion of hibiscus tea with a pH of 2.7, where results of speciation analysis showed that Ni is present in its divalent ionic form. PMID:23232960

Š?an?ar, Janez; Zuliani, Tea; Žigon, Dušan; Mila?i?, Radmila

2012-12-13

192

Matrix-assisted laser desorption/ionization in-source decay combined with tandem time-of-flight mass spectrometry of permethylated oligosaccharides: targeted characterization of specific parts of the glycan structure.  

PubMed

Matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS) has been introduced in recent years as a valuable tool for the structural characterization of permethylated oligosaccharides. In this report, we describe the combination of MALDI in-source decay (ISD) with the subsequent TOF/TOF-MS analyses of specific fragments, allowing the detailed characterization of the selected part of the oligosaccharide molecule. Part of the second-generation fragment ions were different from those observed in conventional MALDI-TOF/TOF-MS experiments. Other fragments, which had already been observed in conventional MALDI-TOF/TOF-MS and again showed up in second-generation fragment analysis, could be assigned to specific parts of the molecule. Our approach disclosed different structural features of the oligosaccharides: due to permethylation, the glycosidic linkage fragments allowed the distinction between terminal, monosubstituted and disubstituted monosaccharides and indicated the oligosaccharide sequence. Moreover, substitution positions were deduced based on characteristic cross-ring fragmentation by high-energy collision-induced fragmentation. In conclusion, combination of MALDI-ISD with TOF/TOF-MS allows the detailed characterization of specific moieties of permethylated oligosaccharides and is, therefore, a powerful technique for structural glycomics. PMID:16470682

Wuhrer, Manfred; Deelder, André M

2006-01-01

193

The power of hyphenated chromatography/time-of-flight mass spectrometry in public health laboratories.  

PubMed

Laboratories devoted to the public health field have to face the analysis of a large number of organic contaminants/residues in many different types of samples. Analytical techniques applied in this field are normally focused on quantification of a limited number of analytes. At present, most of these techniques are based on gas chromatography (GC) or liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS). Using these techniques only analyte-specific information is acquired, and many other compounds that might be present in the samples would be ignored. In this paper, we explore the potential of time-of-flight (TOF) MS hyphenated to GC or LC to provide additional information, highly useful in this field. Thus, all positives reported by standard reference targeted LC-MS/MS methods were unequivocally confirmed by LC-QTOF MS. Only 61% of positives reported by targeted GC-MS/MS could be confirmed by GC-TOF MS, which was due to its lower sensitivity as nonconfirmations corresponded to analytes that were present at very low concentrations. In addition, the use of TOF MS allowed searching for additional compounds in large-scope screening methodologies. In this way, different contaminants/residues not included in either LC or GC tandem MS analyses were detected. This was the case of the insecticide thiacloprid, the plant growth regulator paclobutrazol, the fungicide prochloraz, or the UV filter benzophenone, among others. Finally, elucidation of unknowns was another of the possibilities offered by TOF MS thanks to the accurate-mass full-acquisition data available when using this technique. PMID:22578112

Ibáñez, María; Portolés, Tania; Rúbies, Antoni; Muñoz, Eva; Muñoz, Gloria; Pineda, Laura; Serrahima, Eulalia; Sancho, Juan V; Centrich, Francesc; Hernández, Félix

2012-05-18

194

Profiling of soluble neutral oligosaccharides from treated biomass using solid phase extraction and LC-TOF MS.  

PubMed

Thermochemical pretreatments of cellulosic biomass are known to improve cell wall enzymatic digestibility, while simultaneously releasing substantial amounts of soluble oligosaccharides. Profiling of oligosaccharides released during pretreatment yields information essential for choosing glycosyl hydrolases necessary for cost-effective conversion of cellulosic biomass to desired biofuel/biochemical end-products. In this report we present a methodology for profiling of soluble neutral oligosaccharides released from ammonia fiber expansion (AFEX™)-pretreated corn stover. Our methodology employs solid phase extraction (SPE) enrichment of oligosaccharides using porous graphitized carbon (PGC), followed by high performance liquid chromatography (HPLC) separation using a polymeric amine based column and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). For structural elucidation on the chromatographic time scale, nonselective multiplexed collision-induced dissociation was performed for quasi-simultaneous acquisition of oligosaccharide molecular and fragment masses in a single analysis. These analyses revealed glucans up to degree of polymerization (DP) 22 without modifications. Additionally, arabinoxylans up to DP=6 were detected in pretreated biomass extracts (post-enzymatic digestion). Cross-ring fragment ion abundances were consistent with assignment of linkages between sugar units in glucans and also xylose backbone in arabinoxylans as 1-4 linkages. Comprehensive profiling of soluble oligosaccharides also demonstrated decreases in levels of acetate esters of arabinoxylan oligosaccharides with concomitant increases in nonacetylated oligosaccharides that were consistent with earlier observations of 85% release of acetate esters by AFEX™ pretreatment. PMID:23544634

Vismeh, Ramin; Humpula, James F; Chundawat, Shishir P S; Balan, Venkatesh; Dale, Bruce E; Jones, A Daniel

2013-02-13

195

Fast determination of toxic diethylene glycol in toothpaste by ultra-performance liquid chromatography-time of flight mass spectrometry.  

PubMed

A rapid method for determining diethylene glycol (DEG) in toothpaste based on the use of ultra-performance liquid chromatography (UPLC) coupled to time-of-flight mass spectrometry (TOF-MS) has been developed. The method has been validated in toothpaste samples spiked at different levels, 0.005, 0.1 and 5%, obtaining satisfactory recoveries (74-98%) and relative standard deviations (<4%). Quantification was carried out by using matrix-matched standards calibration. The developed method was applied to several types of toothpaste, making identification and quantification of DEG and other polyethylene glycols (PEG) feasible with very little sample manipulation, as only extraction with water is required. The excellent sensitivity of TOF-MS analysis performed in full-scan acquisition mode allowed the determination of DEG at concentration levels as low as 0.005% in samples and its reliable identification via the mass accuracy measurements provided by this instrument (<5 ppm). PMID:18414832

Hernández, Félix; Ibáñez, María; Sancho, Juan V

2008-04-15

196

Mass spectrometry for direct identification of biosignatures and microorganisms in Earth analogs of Mars  

NASA Astrophysics Data System (ADS)

Rover missions to Mars require portable instruments that use minimal power, require no sample preparation, and provide suitably diagnostic information to an Earth-based exploration team. In exploration of analog environments of Mars it is important to screen rapidly for the presence of biosignatures and microorganisms and especially to identify them accurately.Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) has enormously contributed to the understanding of protein chemistry and cell biology. Without this technique proteomics would most likely not be the important discipline it is today. In this study, besides 'true' proteomics, MALDI-TOF-MS was applied for the analysis of microorganisms for their taxonomic characterization from its beginning. An approach was developed for direct analysis of whole bacterial cells without a preceding fractionation or separation by chromatography or electrophoresis on samples of bacteria from an Antarctic glacier.Supported by comprehensive databases, MALDI-TOF-MS-based identification could be widely accepted within only a few years for bacterial differentiation in Mars analogs and could be a technique of election for Mars exploration.

Garcia-Descalzo, Laura; García-López, Eva; Maria Moreno, Ana; Alcazar, Alberto; Baquero, Fernando; Cid, Cristina

2012-11-01

197

Development of soft extraction method for structural characterization of boreal forest soil proteins with MALDI-TOF/MS  

NASA Astrophysics Data System (ADS)

Nitrogen (N) is usually the nutrient restricting productivity in boreal forests. Forest soils contain a great amount of nitrogen, but only a small part of it is in mineral form. Most part of soil N is bound in the structures of different organic compounds such as proteins, peptides, amino acids and more stabilized, refractory compounds. Due to the fact that soil organic N has a very important role in soil nutrient cycling and in plant nutrition, there is a need for more detailed knowledge of its chemistry in soil. Conventional methods to extract and analyze soil organic N are usually very destructive for structures of higher molecular weight organic compounds, such as proteins. The aim of this study was to characterize proteins extracted from boreal forest soil by "soft" extraction methods in order to maintain their molecular structure. The organic layer (F) from birch forest floor containing 78% of organic matter was sieved, freeze dried, pulverized, and extracted with a citrate or phosphate buffer (pH 6 or 8). Sequential extraction with the citrate or phosphate buffer and an SDS buffer (pH 6.8), slightly modified from the method of Chen et al. (2009, Proteomics 9: 4970-4973), was also done. Proteins were purified from the soil extract by extraction with buffered phenol and precipitated with methanol + 0.1M ammonium acetate at -20°C. Characterization of proteins was performed with matrix assisted laser desorption ionization - time-of-flight mass spectrometry (MALDI-TOF/MS) and the concentration of total proteins was measured using Bradford's method. Bovine serum albumin (BSA) was used as a positive control in the extractions and as a standard protein in Bradford's method. Our results showed that sequential extraction increased the amount of extracted proteins compared to the extractions without the SDS-buffer; however, it must be noted that the use of SDS-buffer very probably increased denaturization of proteins. Purification of proteins from crude soil extracts by phenol extraction was essential prior to measurement of total proteins; there seemed to be a lot of compounds in crude soil extracts that interfere with the analysis of total proteins, causing overestimation in protein concentration. pH of the buffer solution did not seem to be very crucial for the extractability of soil natural proteins, but at the higher pH, the amount of interfering compounds increased. However, the recovery of BSA added was clearly higher at the higher pH. When the protein precipitates were analyzed with MALDI-TOF/MS, a large curve, most likely formed from wide peaks of several compounds, indicate that most of the compounds in the precipitate were <15 kDa or ~20-50 kDa in molecular weight. It seems that in order to identify individual proteins from mass spectra, a separation of compounds with varying molecular weight is needed before the MALDI-TOF/MS analysis. Due to the fact that a relatively high amount of BSA added was not recovered by the extractions and that the intensity of the signals observed in mass spectra was low, it is questionable whether it is possible to extract soil natural proteins effectively from soils containing a high amount of organic matter without destructing the structures of proteins.

Kanerva, Sanna; Ketola, Raimo A.; Kitunen, Veikko; Smolander, Aino; Kotiaho, Tapio

2010-05-01

198

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry-Based Functional Assay for Rapid Detection of Resistance against ?-Lactam Antibiotics  

PubMed Central

Resistance against ?-lactam antibiotics is a growing challenge for managing severe bacterial infections. The rapid and cost-efficient determination of ?-lactam resistance is an important prerequisite for the choice of an adequate antibiotic therapy. ?-Lactam resistance is based mainly on the expression/overexpression of ?-lactamases, which destroy the central ?-lactam ring of these drugs by hydrolysis. Hydrolysis corresponds to a mass shift of +18 Da, which can be easily detected by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Therefore, a MALDI-TOF MS-based assay was set up to investigate different enterobacteria for resistance against different ?-lactam antibiotics: ampicillin, piperacillin, cefotaxime, ceftazidime, ertapenem, imipenem, and meropenem. ?-Lactamases are enzymes that have a high turnover rate. Therefore, hydrolysis can be detected by MALDI-TOF MS already after a few hours of incubation of the bacteria to be tested with the given antibiotic. The comparison of the MS-derived data with the data from the routine procedure revealed identical classification of the bacteria according to sensitivity and resistance. The MALDI-TOF MS-based assay delivers the results on the same day. The approved routine procedures require at least an additional overnight incubation.

Sparbier, Katrin; Schubert, Soren; Weller, Ulrich; Boogen, Christiane

2012-01-01

199

Matrix-assisted laser desorption ionisation-time-of of-flight mass spectrometry of intact cells allows rapid identification of Burkholderia cepacia complex  

Microsoft Academic Search

The present study examined the potential of intact-cell matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS) for a rapid identification of Burkholderia cepacia complex (Bcc) bacteria using an Applied Biosystems 4700 Proteomics Analyser. Two software packages were used to analyse mass profiles based on densitometric curves and peak positions. The 75 strains examined, represented the nine established Bcc species and

Elke Vanlaere; Kjell Sergeant; Peter Dawyndt; Wibke Kallow; Marcel Erhard; Helen Sutton; Diane Dare; Bart Devreese; Bart Samyn; Peter Vandamme

2008-01-01

200

Urinary Metabolites of Isoliquiritigenin in Wistar Rats using UHPLC–TOF–MS-based Xenometabolomics  

Microsoft Academic Search

Isoliquiritigenin, a chalcone found in licorice root and many other plants, has shown potential antioxidant, estrogenic and\\u000a antitumor activities. The present study was to investigate urinary metabolism of isoliquiritigenin in Wistar rats by ultra-high\\u000a pressure liquid chromatography coupled to electrospray ionization TOF–MS (UHPLC–TOF–MS)-based xenometabolomics. Urine samples\\u000a were collected before and after oral administration of isoliquiritigenin, and analyzed by UHPLC–TOF–MS. After

Guangguo Tan; Ziyang Lou; Xing Dong; Wuhong Li; Wenting Liao; Zhenyu Zhu; Yifeng Chai

2011-01-01

201

Metabolome classification of commercial Hypericum perforatum (St. John's Wort) preparations via UPLC-qTOF-MS and chemometrics.  

PubMed

The growing interest in the efficacy of phytomedicines and herbal supplements but also the increase in legal requirements for safety and reliable contents of active principles drive the development of analytical methods for the quality control of complex, multicomponent mixtures as found in plant extracts of value for the pharmaceutical industry. Here, we describe an ultra-performance liquid chromatography method (UPLC) coupled with quadrupole time of flight mass spectrometry (qTOF-MS) measurements for the large scale analysis of H. perforatum plant material and its commercial preparations. Under optimized conditions, we were able to simultaneously quantify and identify 21 metabolites including 4 hyperforins, 3 catechins, 3 naphthodianthrones, 5 flavonoids, 3 fatty acids, and a phenolic acid. Principal component analysis (PCA) was used to ensure good analytical rigorousness and define both similarities and differences among Hypericum samples. A selection of batches from 9 commercially available H. perforatum products available on the German and Egyptian markets showed variable quality, particularly in hyperforins and fatty acid content. PCA analysis was able to discriminate between various preparations according to their global composition, including differentiation between various batches from the same supplier. To the best of our knowledge, this study provides the first approach utilizing UPLC-MS-based metabolic fingerprinting to reveal secondary metabolite compositional differences in Hypericum extract. PMID:22271082

Farag, Mohamed A; Wessjohann, Ludger A

2012-01-23

202

Two classifiers based on serum peptide pattern for prediction of HBV-induced liver cirrhosis using MALDI-TOF MS.  

PubMed

Chronic infection with hepatitis B virus (HBV) is associated with the majority of cases of liver cirrhosis (LC) in China. Although liver biopsy is the reference method for evaluation of cirrhosis, it is an invasive procedure with inherent risk. The aim of this study is to discover novel noninvasive specific serum biomarkers for the diagnosis of HBV-induced LC. We performed bead fractionation/MALDI-TOF MS analysis on sera from patients with LC. Thirteen feature peaks which had optimal discriminatory performance were obtained by using support-vector-machine-(SVM-) based strategy. Based on the previous results, five supervised machine learning methods were employed to construct classifiers that discriminated proteomic spectra of patients with HBV-induced LC from those of controls. Here, we describe two novel methods for prediction of HBV-induced LC, termed LC-NB and LC-MLP, respectively. We obtained a sensitivity of 90.9%, a specificity of 94.9%, and overall accuracy of 93.8% on an independent test set. Comparisons with the existing methods showed that LC-NB and LC-MLP held better accuracy. Our study suggests that potential serum biomarkers can be determined for discriminating LC and non-LC cohorts by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. These two classifiers could be used for clinical practice in HBV-induced LC assessment. PMID:23509784

Cao, Yuan; He, Kun; Cheng, Ming; Si, Hai-Yan; Zhang, He-Lin; Song, Wei; Li, Ai-Ling; Hu, Cheng-Jin; Wang, Na

2013-02-19

203

Identification and characterization of a new IgE-binding protein in mackerel ( Scomber japonicus) by MALDI-TOF-MS  

NASA Astrophysics Data System (ADS)

As fish is one source of the `big eight' food allergens, the prevalence of fish allergy has increased over the past few years. In order to better understand fish allergy, it is necessary to identify fish allergens. Based on the sera from fish-allergenic patients, a 28 kDa protein from local mackerel ( Scomber japonicus), which has not been reported as a fish allergen, was found to be reactive with most of the patients' sera. The 28 kDa protein was analyzed by MALDI-TOF-MS (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry). Mascot search in NCBI database (Date: 08/07/2010) showed that the top protein matched, i.e. triosephosphate isomerase (TPI) from Xiphophorus maculatus and Poecilia reticulata, had a mowse (molecular weight search) score of 98. In addition, TPI from Epinephelus coioides also matched this mackerel protein with a mowse score of 96. Because TPI is considered as an allergen in other non-fish organisms, such as lychee, wheat, latex, archaeopotamobius ( Archaeopotamobius sibiriensis) and crangon ( Crangon crangon), we consider that it may also be an allergen in mackerel.

Wang, Bangping; Li, Zhenxing; Zheng, Lina; Liu, Yixuan; Lin, Hong

2011-03-01

204

A method for determination of phosphatidylethanol from high density lipoproteins by reversed-phase HPLC with TOF-MS detection.  

PubMed

Phosphatidylethanol (PEth) is a unique phospholipid that is formed in the body only in the presence of ethanol. According to a new hypothesis, blood high-density lipoprotein (HDL) particles may act as carriers of PEth and mediate part of the antiatherogenic effects of moderate alcohol drinking. Liquid chromatographic method using reversed-phase C8 column and negative ion mode electrospray ionization-mass spectrometry detection with time-of-flight (TOF) instrument was developed for the determination of very small amounts of PEth that might be present on blood HDL particles. The samples used in the current study were human HDL spiked with PEth and internal standard phosphatidylpropanol (PProp). The use of reversed-phase column enabled a short analysis time of 19 min/injection, which is only one-third of the earlier normal-phase methods reported. Because of the narrow bore column (2.1 mm i.d.) and short analysis time, the solvent consumption was decreased. The sensitivity of detection obtained with TOF-MS was better than that of previous methods, with the detection limit being as low as 1 ng/ml in injected sample (20 pg on-column approximately 28 fmol PEth), corresponding to approximately 6.7 ng of PEth in milliliter of unprepared HDL. Good linearity of detection was obtained for a range of 1-100 ng/ml of PEth, whereas all of the deviations in precision and accuracy were less than 15%. PMID:15866531

Tolonen, Ari; Lehto, Tiina M; Hannuksela, Minna L; Savolainen, Markku J

2005-06-01

205

Metabolomics driven analysis of artichoke leaf and its commercial products via UHPLC-q-TOF-MS and chemometrics.  

PubMed

The demand to develop efficient and reliable analytical methods for the quality control of herbal medicines and nutraceuticals is on the rise, together with an increase in the legal requirements for safe and consistent levels of active principles. Here, we describe an ultra-high performance liquid chromatography method (UHPLC) coupled with quadrupole high resolution time of flight mass spectrometry (qTOF-MS) analysis for the comprehensive measurement of metabolites from three Cynara scolymus (artichoke) cultivars: American Green Globe, French Hyrious, and Egyptian Baladi. Under optimized conditions, 50 metabolites were simultaneously quantified and identified including: eight caffeic acid derivatives, six saponins, 12 flavonoids and 10fatty acids. Principal component analysis (PCA) was used to define both similarities and differences among the three artichoke leaf cultivars. In addition, batches from seven commercially available artichoke market products were analysed and showed variable quality, particularly in caffeic acid derivatives, flavonoid and fatty acid contents. PCA analysis was able to discriminate between various preparations, including differentiation between various batches from the same supplier. To the best of our knowledge, this study provides the first approach utilizing UHPLC-MS based metabolite fingerprinting to reveal secondary metabolite compositional differences in artichoke leaf extracts. PMID:23902683

Farag, Mohamed A; El-Ahmady, Sherweit H; Elian, Fatma S; Wessjohann, Ludger A

2013-07-29

206

Peptide-Mass Profiles of Polyvinylidene Difluoride-Bound Proteins by Matrix-Assisted Laser Desorption\\/Ionization Time-of-Flight Mass Spectrometry in the Presence of Nonionic Detergents  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS), in conjunction with enzymatic digestion of proteins and molecular weight search of peptide-mass database is a powerful technique for peptide\\/protein identification. Ideally, peptide mixtures should be compatible with both MALDI-TOF and microsequencing. In our laboratory, enzymatic digestion and extraction of peptides from polyvinylidene difluoride (PVDF)-bound proteins is performed in the presence of

Farzin Gharahdaghi; Michele Kirchner; Joseph Fernandez; Sheenah M. Mische

1996-01-01

207

An optimized protein in-gel digest method for reliable proteome characterization by MALDI–TOF–MS analysis  

Microsoft Academic Search

Human lung epithelial cells (A549) were used as a model to develop a reliable proteome characterization method by peptide mass fingerprinting (PMF). Lung cell lysate proteins and protein standards were separated by 2D-gel electrophoresis, stained with Coomassie blue, gel plugs were subjected to commonly adapted as well as optimized in-gel digestion\\/sample preparation methods. Samples were analyzed by MALDI-TOF-MS. Optimization parameters

P. Kumarathasan; S. Mohottalage; P. Goegan; R. Vincent

2005-01-01

208

Structural characterization of N-linked oligosaccharides on monoclonal antibody cetuximab by the combination of orthogonal matrix-assisted laser desorption\\/ionization hybrid quadrupole–quadrupole time-of-flight tandem mass spectrometry and sequential enzymatic digestion  

Microsoft Academic Search

Cetuximab is a novel therapeutic monoclonal antibody with two N-glycosylation sites: a conserved site in the CH2 domain and a second site within the framework 3 of the variable portion of the heavy chain. The detailed structures of these oligosaccharides were successfully characterized using orthogonal matrix-assisted laser desorption\\/ionization hybrid quadrupole–quadrupole time-of-flight mass spectrometry (oMALDI Qq–TOF MS) and tandem mass spectrometry

Jun Qian; Tun Liu; Li Yang; Ann Daus; Richard Crowley; Qinwei Zhou

2007-01-01

209

Application of mass spectrometry for the detection of glycation and oxidation products in milk proteins.  

PubMed

Protein mass spectometry techniques, such as electrospray ionization mass spectrometry or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), are effective methods to screen for protein modifications derived from the Maillard reaction. The analysis of the intact proteins reveals the major modification, most commonly the Amadori product, whereas partial enzymatic hydrolysis prior to mass spectrometry additionally allows the detection of minor adducts. Therefore, a mass spectrometric method was developed for the analysis of whey protein modifications occurring during heat treatment. The two main whey proteins, alpha-lactalbumin and beta-lactoglobulin, were incubated with lactose in a milk model and modifications were recorded using MALDI-TOF-MS. The analysis of the intact proteins revealed protein species with 0-4 lactulosyl residues. Partial enzymatic hydrolysis with endoproteinase AspN prior to mass spectrometric analysis enabled the detection of further modifications and their localization in the amino acid sequence. Detected modifications were lactulosyllysine, N epsilon-(carboxymethyl)lysine, lysine aldehyde, methionine sulfoxide, cyclization of N-terminal glutamic acid to a pyrrolidone, and oxidation of cysteine or tryptophan. Protein modifications in heated milk and commercially available dairy products can be analyzed after the separation of the milk proteins using one-dimensional SDS-PAGE. PMID:18448807

Meltretter, Jasmin; Pischetsrieder, Monika

2008-04-01

210

Electrosprayed droplet impact/secondary ion mass spectrometry  

NASA Astrophysics Data System (ADS)

A new ionization method, electrosprayed droplet impact ionization (EDI), has been developed for mass spectrometry. The charged droplets formed by electrospraying 1 M acetic acid aqueous solution are sampled through an orifice with a diameter of 400 ?m into the first vacuum chamber, transported into a quadrupole ion guide and accelerated by 10 kV after exiting the ion guide. The m/z of the primary droplet projectiles range from 10 000 to 50 000. The droplets impact on a dry solid sample deposited on a stainless steel substrate. No matrix was used for the sample preparation. The secondary ions formed by the impact are transported to a second quadrupole ion guide and mass-analyzed by an orthogonal TOF-MS. Intense molecular-related ions are detected for drugs, amino acids, peptides and proteins. EDI is found to be very sensitive to molecules present near the surface of the sample.

Hiraoka, K.; Asakawa, D.; Fujimaki, S.; Takamizawa, A.; Mori, K.

2006-04-01

211

MALDI-TOF MS Enables the Rapid Identification of the Major Molecular Types within the Cryptococcus neoformans/C. gattii Species Complex  

PubMed Central

Background The Cryptococcus neoformans/C. gattii species complex comprises two sibling species that are divided into eight major molecular types, C. neoformans VNI to VNIV and C. gattii VGI to VGIV. These genotypes differ in host range, epidemiology, virulence, antifungal susceptibility and geographic distribution. The currently used phenotypic and molecular identification methods for the species/molecular types are time consuming and expensive. As Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) offers an effective alternative for the rapid identification of microorganisms, the objective of this study was to examine its potential for the identification of C. neoformans and C. gattii strains at the intra- and inter-species level. Methodology Protein extracts obtained via the formic acid extraction method of 164 C. neoformans/C. gattii isolates, including four inter-species hybrids, were studied. Results The obtained mass spectra correctly identified 100% of all studied isolates, grouped each isolate according to the currently recognized species, C. neoformans and C. gattii, and detected potential hybrids. In addition, all isolates were clearly separated according to their major molecular type, generating greater spectral differences among the C. neoformans molecular types than the C. gattii molecular types, most likely reflecting a closer phylogenetic relationship between the latter. The number of colonies used and the incubation length did not affect the results. No spectra were obtained from intact yeast cells. An extended validated spectral library containing spectra of all eight major molecular types was established. Conclusions MALDI-TOF MS is a rapid identification tool for the correct recognition of the two currently recognized human pathogenic Cryptococcus species and offers a simple method for the separation of the eight major molecular types and the detection of hybrid strains within this species complex in the clinical laboratory. The obtained mass spectra provide further evidence that the major molecular types warrant variety or even species status.

Firacative, Carolina; Trilles, Luciana; Meyer, Wieland

2012-01-01

212

Development of High-Performance Liquid Chromatography-Time-of-Flight Mass Spectrometry for the Simultaneous Characterization and Quantitative Analysis of Gingerol-Related Compounds in Ginger Products.  

PubMed

Liquid chromatography-time-of-flight mass spectrometry (LC-TOF/MS) was established for the simultaneous separation, identification, and quantification of gingerol-related compounds in ginger products. The established method has been shown to provide a satisfactory linearity (r > 0.999) in a wide range (5-5000 ng/mL), low limits of detection and quantification, high precision, and inter- and intraday repeatability. The detection sensitivity of gingerols and shogaols by TOF/MS was 70-100 times higher than conventional UV detection at 288 nm. In this study, 19 ginerol-related compounds in the samples were identified and quantified by the established LC-TOF/MS method. The dried ginger powder products contained the highest quantity of gingerol-related compounds (7126.3-13789.0 ?g/g), followed by fresh ginger products (2007.9-2790.0 ?g/g), powdered ginger tea products (77.29-81.75 ?g/g), and hot water ginger extracts (54.59-123.23 ?g/mL). Shogaols were not found in fresh gingers. This paper represents the first report on the LC-TOF/MS analysis for the simultaneous characterization and quantification of gingerol-related compounds in ginger products. PMID:22985300

Park, Ji Su; Jung, Mun Yhung

2012-10-01

213

MALDI-TOF mass spectrometry-based identification of group A Streptococcus isolated from areas of the 2011 scarlet fever outbreak in china.  

PubMed

There was a dramatic increase in scarlet fever cases in China from March to July 2011. Group A Streptococcus (GAS) is the only pathogen known to cause scarlet fever. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) coupled to Biotyper system was used for GAS identification in 2011. A local reference database (LRD) was constructed, evaluated and used to identify GAS isolates. The 75 GAS strains used to evaluate the LRD were all identified correctly. Of the 157 suspected ?-hemolytic strains isolated from 298 throat swab samples, 127 (100%) and 120 (94.5%) of the isolates were identified as GAS by the MALDI-TOF MS system and the conventional bacitracin sensitivity test method, respectively. All 202 (100%) isolates were identified at the species level by searching the LRD, while 182 (90.1%) were identified by searching the original reference database (ORD). There were statistically significant differences with a high degree of credibility at species level (?(2)=6.052, P<0.05 between the LRD and ORD). The test turnaround time was shortened 36-48h, and the cost of each sample is one-tenth of the cost of conventional methods. Establishing a domestic database is the most effective way to improve the identification efficiency using a MALDI-TOF MS system. MALDI-TOF MS is a viable alternative to conventional methods and may aid in the diagnosis and surveillance of GAS. PMID:23305889

Xiao, Di; You, Yuanhai; Bi, Zhenwang; Wang, Haibin; Zhang, Yongchan; Hu, Bin; Song, Yanyan; Zhang, Huifang; Kou, Zengqiang; Yan, Xiaomei; Zhang, Menghan; Jin, Lianmei; Jiang, Xihong; Su, Peng; Bi, Zhenqiang; Luo, Fengji; Zhang, Jianzhong

2013-01-07

214

Detection of chemical weapon agents and simulants using chemical ionization reaction time-of-flight mass spectrometry.  

PubMed

Chemical ionization reaction time-of-flight mass spectrometry (CIR-TOF-MS) has been used for the analysis of prepared mixtures of chemical weapon agents (CWAs) sarin and sulfur mustard. Detection of the CWA simulants 2-chloroethyl ethyl sulfide, triethyl phosphate, and dimethyl methyl phosphonate has also been investigated. Chemical ionization of all the agents and simulants was shown to be possible using the CIR-TOF-MS technique with a variety of reagent ions, and the sensitivity was optimized by variation of instrument parameters. The ionization process was found to be largely unaffected by sample humidity levels, demonstrating the potential suitability of the method to a range of environmental conditions, including the analysis of CWAs in air and in the breath of exposed individuals. PMID:17894471

Cordell, Rebecca L; Willis, Kerry A; Wyche, Kevin P; Blake, Robert S; Ellis, Andrew M; Monks, Paul S

2007-09-26

215

PTR-TOF-MS and data-mining methods for rapid characterisation of agro-industrial samples: influence of milk storage conditions on the volatile compounds profile of Trentingrana cheese.  

PubMed

Proton transfer reaction-mass spectrometry (PTR-MS), a direct injection mass spectrometric technique based on an efficient implementation of chemical ionisation, allows for fast and high-sensitivity monitoring of volatile organic compounds (VOCs). The first implementations of PTR-MS, based on quadrupole mass analyzers (PTR-Quad-MS), provided only the nominal mass of the ions measured and thus little chemical information. To partially overcome these limitations and improve the analytical capability of this technique, the coupling of proton transfer reaction ionisation with a time-of-flight mass analyser has been recently realised and commercialised (PTR-TOF-MS). Here we discuss the very first application of this new instrument to agro-industrial problems and dairy science in particular. As a case study, we show here that the rapid PTR-TOF-MS fingerprinting coupled with data-mining methods can quickly verify whether the storage condition of the milk affects the final quality of cheese and we provide relevant examples of better compound identification in comparison with the previous PTR-MS implementations. In particular, 'Trentingrana' cheese produced by four different procedures for milk storage are compared both in the case of winter and summer production. It is indeed possible to set classification models with low prediction errors and to identify the chemical formula of the ion peaks used for classification, providing evidence of the role that this novel spectrometric technique can play for fundamental and applied agro-industrial themes. PMID:20690164

Fabris, Alessandra; Biasioli, Franco; Granitto, Pablo M; Aprea, Eugenio; Cappellin, Luca; Schuhfried, Erna; Soukoulis, Christos; Märk, Tilmann D; Gasperi, Flavia; Endrizzi, Isabella

2010-09-01

216

MASS SPECTROMETRY  

DOEpatents

method is described for operating a mass spectrometer to improve its resolution qualities and to extend its period of use substantially between cleanings. In this method, a small amount of a beta emitting gas such as hydrogen titride or carbon-14 methane is added to the sample being supplied to the spectrometer for investigation. The additive establishes leakage paths on the surface of the non-conducting film accumulating within the vacuum chamber of the spectrometer, thereby reducing the effect of an accumulated static charge on the electrostatic and magnetic fields established within the instrument. (AEC)

Friedman, L.

1962-01-01

217

Electrohydrodynamic mass spectrometry  

SciTech Connect

A review of the principles, development, and status of electrohydrodynamic mass spectrometry, with 111 references, is presented. Areas discussed include: Electrospray; Electrohydrodynamic ion emission; Electrohydrodynamic ionization mass spectrometry; Electrohydrodynamic mass spectrometry of organic compounds; The role of solvation; Emission stability; Comparison with field desorption; Liquid chromatography interfaces; Polymer molecular-weight distributions; Solution chemistry; Sampling efficiencies.

Cook, K.D.

1986-01-01

218

Control of strobilurin fungicides in wheat using direct analysis in real time accurate time-of-flight and desorption electrospray ionization linear ion trap mass spectrometry.  

PubMed

Ambient mass spectrometry has been used for the analysis of strobilurin residues in wheat. The use of this novel, challenging technique, employing a direct analysis in a real time (DART) ion-source coupled with a time-of-flight mass spectrometer (TOF MS) and a desorption electrospray ionization (DESI) source coupled with a linear ion trap tandem MS (LIT MS(n)), permitted a direct screen of the occurrence of target fungicides in treated grains in less than 1 min. For quantification purpose by DART-TOF MS, an ethyl acetate extract had to be prepared. With the use of a prochloraz as an internal standard, the performance characteristics obtained by repeated analyses of extract, spiked at 50 microg kg(-1) with six strobilurins (azoxystrobin, picoxystrobin, dimoxystrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin), were in the following range: recoveries 78-92%, repeatability (RSD) 8-15%, linearity (R(2)) 0.9900-0.9978. The analysis of wheat with incurred strobilurin residues demonstrated good trueness of data generated by the DART-TOF MS method; the results were in a good agreement with those obtained by the conventional approach, i.e., by the QuEChERS sample handling procedure followed by identification/quantification employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Tandem mass spectrometry using DESI-LIT MS(n) provided a sufficient number of product ions for confirmation of the identity of azoxystrobin and pyraclostrobin in incurred wheat samples. PMID:19007189

Schurek, Jakub; Vaclavik, Lukas; Hooijerink, H Dick; Lacina, Ondrej; Poustka, Jan; Sharman, Matthew; Caldow, Marianne; Nielen, Michel W F; Hajslova, Jana

2008-12-15

219

Evaluation of inter-day and inter-individual variability of tear peptide/protein profiles by MALDI-TOF MS analyses  

PubMed Central

Purpose To characterize the tear film peptidome and low molecular weight protein profiles of healthy control individuals, and to evaluate changes due to day-to-day and individual variation and tear collection methods, by using solid phase extraction coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling. Methods The tear protein profiles of six healthy volunteers were analyzed over seven days and inter-day and inter-individual variability was evaluated. The bilaterality of tear film and the effect of tear collection methods on protein profiles were also analyzed in some of these patients. MALDI-TOF MS analyses were performed on tear samples purified by using a solid phase extraction (SPE) method based on C18 functionalized magnetic beads for peptide and low molecular weight protein enrichment, focusing spectra acquisition on the 1 to 20 kDa range. Spectra were analyzed using principal component analysis (PCA) with MultiExperiment Viewer (TMeV) software. Volunteers were examined in terms of tear production status (Schirmer I test), clinical assessment of palpebral lids and meibomian glands, and a subjective OSD questionnaire before tear collection by a glass micro-capillary. Results Analysis of peptides and proteins in the 1–20 kDa range showed no significant inter-day differences in tear samples collected from six healthy individuals during seven days of monitoring, but revealed subtle intrinsic inter-individual differences. Profile analyses of tears collected from the right and left eyes confirmed tear bilaterality in four healthy patients. The addition of physiologic serum for tear sample collection did not affect the peptide and small protein profiles with respect to the number of resolved peaks, but it did reduce the signal intensity of the peaks, and increased variability. Magnetic beads were found to be a suitable method for tear film purification for the profiling study. Conclusions No significant variability in tear peptide and protein profiles below 20 kDa was found in healthy controls over a seven day period, nor in right versus left eye profiles from the same individual. Subtle inter-individual differences can be observed upon tear profiling analysis and confirm intrinsic variability between control subjects. Addition of physiologic serum for tear collection affects the proteome and peptidome in terms of peak intensities, but not in the composition of the profiles themselves. This work shows that MALDI-TOF MS coupled with C18 magnetic beads is an effective and reproducible methodology for tear profiling studies in the clinical monitoring of patients.

Gonzalez, Nerea; Iloro, Ibon; Duran, Juan A.; Elortza, Felix

2012-01-01

220

Metabolite profiling of plant extracts by ultra-high-pressure liquid chromatography at elevated temperature coupled to time-of-flight mass spectrometry  

Microsoft Academic Search

Detailed metabolite profiling of crude plant extracts, mandatory for both quality control and metabolomics purposes, requires high-resolution separation and sensitive detection with a reasonable sample throughput. In this respect, the use of ultra-high-pressure liquid chromatography (UHPLC) working at high temperature (HT) and coupled to time-of-flight mass spectrometry (TOF-MS) was evaluated in the present study in terms of achievable peak capacities

Elia Grata; Davy Guillarme; Gaetan Glauser; Julien Boccard; Pierre-Alain Carrupt; Jean-Luc Veuthey; Serge Rudaz; Jean-Luc Wolfender

2009-01-01

221

Lipid analysis of human spermatozoa and seminal plasma by MALDI-TOF mass spectrometry and NMR spectroscopy — effects of freezing and thawing  

Microsoft Academic Search

In the present study, the applicability of proton NMR spectroscopy and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) to the analysis of the lipid composition of human spermatozoa and seminal fluids as well as changes after cryopreservation of human spermatozoa was investigated. Whereas NMR spectra primarily indicated a high content of double bonds within the spermatozoa but

Jürgen Schiller; Jürgen Arnhold; Hans-Jürgen Glander; Klaus Arnold

2000-01-01

222

Using matrix-assisted laser desorption ionization-time of flight mass spectrometry to detect carbapenem resistance within 1 to 2.5 hours.  

PubMed

In recent years, the percentage of carbapenem-resistant bacteria has increased at an alarming pace and become a major threat for patient survival. Carbapenemase-induced carbapenem resistance can be confirmed through the detection of carbapenem degradation using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This method works for strains carrying NDM-1, VIM-1, VIM-2, KPC-2, and different IMP enzymes. PMID:21795515

Burckhardt, Irene; Zimmermann, Stefan

2011-07-27

223

Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry To Detect Carbapenem Resistance within 1 to 2.5 Hours?  

PubMed Central

In recent years, the percentage of carbapenem-resistant bacteria has increased at an alarming pace and become a major threat for patient survival. Carbapenemase-induced carbapenem resistance can be confirmed through the detection of carbapenem degradation using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This method works for strains carrying NDM-1, VIM-1, VIM-2, KPC-2, and different IMP enzymes.

Burckhardt, Irene; Zimmermann, Stefan

2011-01-01

224

High-performance liquid chromatography coupled to direct analysis in real time mass spectrometry: Investigations on gradient elution and influence of complex matrices on signal intensities  

Microsoft Academic Search

Direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) has been tested for its suitability as a detector for gradient elution HPLC. Thereby a strong dependency of signal intensity on the amount of organic solvent present in the eluent could be observed. Adding a make-up liquid (iso-propanol) post-column to the HPLC effluent greatly enhanced detection limits for early eluting

Susanne Beißmann; Wolfgang Buchberger; Robert Hertsens; Christian W. Klampfl

2011-01-01

225

Analysis of the lipid composition of human and boar spermatozoa by MALDI-TOF mass spectrometry, thin layer chromatography and 31P NMR spectroscopy  

Microsoft Academic Search

Alterations in the phospholipid (PL) composition of spermatozoal membranes occur during the fertilization process. Furthermore, membrane lipid composition is of high interest with respect to cryopreservation. The PL and fatty acid compositions of human and boar spermatozoa are compared by using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) in combination with thin-layer chromatography and 31P NMR spectroscopy.

Jacqueline Leßig; Claudia Gey; Rosemarie Süß; Jürgen Schiller; Hans-Jürgen Glander; Jürgen Arnhold

2004-01-01

226

Capillary electrophoretic characterization of PEGylated human parathyroid hormone with matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry  

Microsoft Academic Search

A capillary electrophoretic method (CE) for characterizing PEGylated human parathyroid hormone 1–34 (PTH) with matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is described. CE was used to optimize the PEGylation of PTH through control of the reaction pH and the molar ratio of reactants with the advantages of minimal sample consumption and high separation capacity. The mono-PEGylated PTH (mono-PEG-PTH)

Dong Hee Na; Kang Choon Lee

2004-01-01

227

Multi-residue analysis of pharmaceuticals in wastewater by ultra-performance liquid chromatography–quadrupole–time-of-flight mass spectrometry  

Microsoft Academic Search

In this work, a new multi-residue method using ultra-performance liquid chromatography (UPLC) quadrupole-time-of-flight mass spectrometry (Q–TOF–MS) was developed for screening and confirmation of 29 pharmaceutical compounds belonging to different therapeutical classes: analgesics and antiinflammatories, lipid regulating agents cholesterol lowering statin agents, psychiatric drugs, anti ulcer agents, histamine H2 receptor antagonist, antibiotics and beta-blockers. UPLC uses columns packed with 1.7?m particles

Mira Petrovic; Meritxell Gros; Damia Barcelo

2006-01-01

228

Application of matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry for monitoring the digestion of phosphatidylcholine by pancreatic phospholipase A 2  

Microsoft Academic Search

Different methods were established for monitoring the phospholipase A2(PLA2) activity but all of them are rather cumbersome and time consuming. In this paper we have investigated the suitability of matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the determination of the PLA2 activity. Phosphatidylcholine (PC) was digested with pancreatic PLA2 under different conditions, i.e., various Ca2+, PC, and PLA2

Marijana Petkovi?; Julia Müller; Matthias Müller; Jürgen Schiller; Klaus Arnold; Jürgen Arnhold

2002-01-01

229

Application of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of the fastidious pediatric pathogens aggregatibacter, eikenella, haemophilus, and kingella.  

PubMed

The accuracy of matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) in the identification of Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella (HACEK) species was compared to that of phenotypic methods (Remel RapID and Vitek 2). Overall, Vitek MS correctly identified more isolates, incorrectly identified fewer isolates, and failed to identify fewer isolates than both phenotypic methods. PMID:23966506

Powell, Eleanor A; Blecker-Shelly, Deborah; Montgomery, Sandra; Mortensen, Joel E

2013-08-21

230

Rapid genotyping of single nucleotide polymorphisms influencing warfarin drug response by surface-enhanced laser desorption and ionization time-of-flight (SELDI-TOF) mass spectrometry.  

PubMed

Warfarin exhibits significant interindividual variability in dosing requirements. Different drug responses are partly attributed to the single nucleotide polymorphisms (SNPs) that influence either drug action or drug metabolism. Rapid genotyping of these SNPs helps clinicians to choose appropriate initial doses to quickly achieve anticoagulation effects and to prevent complications. We report a novel application of surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF MS) in the rapid genotyping of SNPs that impact warfarin efficacy. The SNPs were first amplified by PCR and then underwent single base extension to generate the specific SNP product. Next, genetic variants displaying different masses were bound to Q10 anionic proteinChips and then genotyped by using SELDI-TOF MS in a multiplex fashion. SELDI-TOF MS offered unique properties of on-chip sample enrichment and clean-ups, which streamlined the testing procedures and eliminated many tedious experimental steps required by the conventional MS-based method. The turn-around time for genotyping three known warfarin-related SNPs, CYP2C9*2, CYP2C9*3, and VKORC1 3673G>A by SELDI-TOF MS was less than 5 hours. The analytical accuracy of this method was confirmed both by bidirectional DNA sequencing and by comparing the genotype results (n = 189) obtained by SELDI-TOF MS to reports from a clinical reference laboratory. This new multiplex genotyping method provides an excellent clinical laboratory platform to promote personalized medicine in warfarin therapy. PMID:20075209

Yang, Shangbin; Xu, LiHui; Wu, Haifeng M

2010-01-14

231

Elemental, Isotopic, and Organic Analysis on Mars with Laser TOF-MS  

NASA Astrophysics Data System (ADS)

The in-depth landed exploration of Mars will require increasingly sophisticated robotic analytical tools for both in situ composition science [1] and reconnaissance for sample return [2]. Beyond dust, rock surfaces, and topsoil, samples must be accessed within rocks and ice, well below surface soil, and possibly in elevated deposit layers. A range of spatial scales will be studied, and for the most information-rich microscopic analyses, samples must be acquired, prepared, and positioned with high precision. In some cases samples must also be brought into a vacuum chamber. After expending such resources, it will be important to apply techniques that provide a wide range of information about the samples. Microscopy, mineralogy, and molecular/organic, elemental, and isotopic analyses are all needed, at a minimum, to begin to address the in situ goals at Mars. These techniques must work as an efficient suite to provide layers of data, each layer helping to determine if further analysis on a given sample is desired. In the spirit of broad-band and efficient data collection, we are developing miniature laser time-of-flight mass spectrometers (TOF-MS) for elemental, isotopic, and molecular/organic microanalysis of unprepared solid samples. Laser TOF-MS uses a pulsed laser to volatilize and ionize material from a small region on the sample. The laser energy and focus can be adjusted for atomic and molecular content, sampling area, and depth. Ions travel through the instrument and are detected at a sequence of times proportional to the square root of their mass-to- charge ratios. Thus, each laser pulse produces a complete mass spectrum (in less than 50 microseconds). These instruments can now be significantly miniaturized (potentially to the size of a soda can) without a loss in performance. This effort is reviewed here with an emphasis on applications to Mars exploration.

Brinckerhoff, W. B.; Cornish, T. J.

2000-07-01

232

Comparison of MALDI-TOF MS and VITEK 2 system for laboratory diagnosis of Granulicatella and Abiotrophia species causing invasive infections.  

PubMed

Granulicatella and Abiotrophia spp. were known as nutritionally variant streptococci (NVS). Such strains have caused major diagnostic difficulties due to fastidious culturing and unspecific colony morphology. The present study is aimed at comparing the performance of laboratory available diagnostic methods for NVS isolates and determining the antimicrobial susceptibility of these isolates. Fourteen clinical invasive isolates, consisting of 10 Granulicatella adiacens, 1 Granulicatella elegans, and 3 Abiotrophia defectiva were in parallel analyzed by 2 matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems, i.e., Bruker MS and Vitek MS, as well as Vitek 2 for the species determination. 16S rRNA gene sequencing was applied as a reference method. The Vitek MS gave correct identification for all 14 isolates. The Bruker MS could correctly identify 8/10 G. adiacens, 0/1 G. elegans, and 3/3 A. defectiva isolates at the first analysis occasion, and all 14 isolates became identifiable after repeated tests. The Vitek 2 system could identify 6/10 G. adiacens, 1/1 G. elegans, and 2/3 A. defectiva isolates at the species level. Antimicrobial susceptibilities of 11 antibiotics were determined by Etest. Resistance against ciprofloxacin, ceftriaxone, rifampicin, and tetracycline were observed in 4, 10, 4, and 1 isolates, respectively. In conclusion, MALDI-TOF MS is a useful tool for the rapid diagnosis of NVS. Phenotypic testing by Vitek 2 is only partially effective for the accurate identification of such strains. The emergence of resistant NVS isolates indicates the necessity of monitoring antimicrobial susceptibilities of such uncommon pathogens. PMID:24034902

Ratcliffe, Paul; Fang, Hong; Thidholm, Ellinor; Boräng, Stina; Westling, Katarina; Ozenci, Volkan

2013-09-10

233

An evaluation of three processing methods and the effect of reduced culture times for faster direct identification of pathogens from BacT/ALERT blood cultures by MALDI-TOF MS.  

PubMed

Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is a fast and reliable method for the identification of bacteria from agar media. Direct identification from positive blood cultures should decrease the time to obtaining the result. In this study, three different processing methods for the rapid direct identification of bacteria from positive blood culture bottles were compared. In total, 101 positive aerobe BacT/ALERT bottles were included in this study. Aliquots from all bottles were used for three bacterial processing methods, i.e. the commercially available Bruker's MALDI Sepsityper kit, the commercially available Molzym's MolYsis Basic5 kit and a centrifugation/washing method. In addition, the best method was used to evaluate the possibility of MALDI application after a reduced incubation time of 7 h of Staphylococcus aureus- and Escherichia coli-spiked (1,000, 100 and 10 colony-forming units [CFU]) aerobe BacT/ALERT blood cultures. Sixty-six (65%), 51 (50.5%) and 79 (78%) bottles were identified correctly at the species level when the centrifugation/washing method, MolYsis Basic 5 and Sepsityper were used, respectively. Incorrect identification was obtained in 35 (35%), 50 (49.5%) and 22 (22%) bottles, respectively. Gram-positive cocci were correctly identified in 33/52 (64%) of the cases. However, Gram-negative rods showed a correct identification in 45/47 (96%) of all bottles when the Sepsityper kit was used. Seven hours of pre-incubation of S. aureus- and E. coli-spiked aerobe BacT/ALERT blood cultures never resulted in reliable identification with MALDI-TOF MS. Sepsityper is superior for the direct identification of microorganisms from aerobe BacT/ALERT bottles. Gram-negative pathogens show better results compared to Gram-positive bacteria. Reduced incubation followed by MALDI-TOF MS did not result in faster reliable identification. PMID:22080416

Loonen, A J M; Jansz, A R; Stalpers, J; Wolffs, P F G; van den Brule, A J C

2011-11-12

234

On-line analysis by capillary separations interfaced to an ion trap storage\\/reflectron time-of-flight mass spectrometer  

Microsoft Academic Search

The interface of high-resolution capillary separation methods to time-of-flight mass spectrometry (TOF-MS) has generated considerable interest since TOF can provide the rapid and sensitive detection required by high resolution separations. In recent years, our laboratory has developed a variety of high-resolution capillary separation methods interfaced to TOF-MS via an ion trap storage\\/reflectron time-of-flight (IT\\/reTOF) instrument. Using this hybrid configuration, detection

Jing-Tao Wu; Mark G Qian; Michael X Li; Kefei Zheng; Peiqing Huang; David M Lubman

1998-01-01

235

Molecular diversity of cereulide detected by means of nano-HPLC-ESI-Q-TOF-MS  

NASA Astrophysics Data System (ADS)

Cereulide is a cyclic dodecadepsipeptide from a pathogenic bacteria Bacillus cereus, which shows the emetic toxicity. Molecular diversity, or variety in homologation was found as a minor constituent of this cyclic peptide. Its molecular weight is 1152 but its homologs were observed as 1138 and 1166, which had 14 mass lower and higher differences from cereulide. This homologation was observed in about 10% of cereulide. It seemed to be difficult to determine the heterogeneous amino acids directly by MS/MS analysis on the intact molecules of cereulide. And hydrolysis of this cyclic peptide gave dipeptides, which were analyzed to determine their heterogeneous components by means of nano-HPLC-ESI-Q-TOF-MS and MS/MS. Among all amino- and oxy-acids, we found that O-Val and O-Leu were the keys of variation in cereulide. These findings will be significant to establish an identification method for pathogenic bacteria on the basis of biosynthetic pathways.

Pitchayawasin, Suthasinee; Isobe, Minoru; Kuse, Masaki; Franz, Thomas; Agata, Norio; Ohta, Michio

2004-07-01

236

Rapid and global detection and characterization of aconitum alkaloids in Yin Chen Si Ni Tang, a traditional Chinese medical formula, by ultra performance liquid chromatography–high resolution mass spectrometry and automated data analysis  

Microsoft Academic Search

An improved method employing Metabolynx XS with mass defect filter (MDF), a post-acquisition data processing software, was developed and applied for global detection of aconitum alkaloids in Yin Chen Si Ni Tang, a traditional Chinese medical formula (TCMF). The full-scan LC–MS\\/MS data sets with extra mass were acquired using ultra performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC\\/Q-TOF-MS) with

Guangli Yan; Hui Sun; Wenjun Sun; Li Zhao; Xiangcai Meng; Xijun Wang

2010-01-01

237

Performance of matrix-assisted laser desorption-time of flight mass spectrometry for identification of clinical yeast isolates.  

PubMed

Accurate and fast yeast identification is important when treating patients with invasive fungal disease as susceptibility to antifungal agents is highly species related. Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) provides a powerful tool with a clear potential to improve current diagnostic practice. Two MALDI-TOF-MS-systems (BioTyper/Bruker and Saramis/AXIMA) were evaluated using: (i) A collection of 102 archived, well characterised yeast isolates representing 14 different species and (ii) Prospectively collected isolates obtained from clinical samples at two participating laboratories. Of the 102 archived isolates, 81 (79%) and 92 (90%) were correctly identified by Saramis/AXIMA and BioTyper/Bruker respectively. Saramis/AXIMA was unable to separate Candida albicans, C. africana and C. dubliniensis in 13 of 32 isolates. After manual interpretation of the mass spectra output, all 13 isolates were correctly identified, resulting in an overall identification performance of 92%. No misidentifications occurred with the two systems. Of the routine isolates one laboratory identified 99/99 (100%) and 90/99 (91%) to species level by Saramis/Axima and conventional identification, respectively, whereas the other laboratory identified 83/98 (85%) to species level by both BioTyper/Bruker and conventional identification. Both MALDI-TOF-MS systems are fast, have built-in databases that cover the majority of clinically relevant Candida species, and have an accuracy that outperforms our conventional identification systems. PMID:22924975

Rosenvinge, Flemming S; Dzajic, Esad; Knudsen, Elisa; Malig, Sanne; Andersen, Line B; Løvig, Annette; Arendrup, Maiken C; Jensen, Thøger G; Gahrn-Hansen, Bente; Kemp, Michael

2012-08-26

238

PrepMS: TOF MS data graphical preprocessing tool  

Microsoft Academic Search

Summary: We introduce a simple-to-use graphical tool that enables researchers to easily prepare time-of-flight mass spectrometry data for analysis. For ease of use, the graphical executable provides default parameter settings experimentally determined to work well in most situations. These values can be changed by the user if desired. PrepMS is a stand-alone application made freely available (open source), and is

Yuliya V. Karpievitch; Elizabeth G. Hill; Adam J. Smolka; Jeffrey S. Morris; Kevin R. Coombes; Keith A. Baggerly; Jonas S. Almeida

2007-01-01

239

[Analysis of insecticidal crystal proteins from Bacillus thuringiensis strain 4.0718 through two-dimensional gel electrophoresis and MALDI-TOF-mass spectrometry].  

PubMed

The present study analyses the insecticidal crystal proteins (ICPs) from Bacillus thuringiensis strain 4.0718 through two-dimensional electrophoresis and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). By comparing and optimizing the composition of lysis solution, the volume of sample loading and the protocol for isoelectric focusing, a well-focused 2-DE map with high resolution and reproducibility was achieved for the first time. And after an tryptic enzymolisis and a test of part of protein spots by means of MALDI-TOF-MS, the peptides mass fingerprint (PMF) was obtained and, by referring to Swiss-Prot, Cry1Ac and Cry2Aa contained in Bt 4.0718 were identified, with their molecular weights 134160 Da and 71097 Da respectively. PMID:15989249

Song, Sheng; Xia, Li-qiu; Huang, Jiang-li; Sun, Yun-jun; Ding, Xue-zhi

2005-06-01

240

Matrix-assisted laser desorption ionisation-time-of of-flight mass spectrometry of intact cells allows rapid identification of Burkholderia cepacia complex.  

PubMed

The present study examined the potential of intact-cell matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS) for a rapid identification of Burkholderia cepacia complex (Bcc) bacteria using an Applied Biosystems 4700 Proteomics Analyser. Two software packages were used to analyse mass profiles based on densitometric curves and peak positions. The 75 strains examined, represented the nine established Bcc species and some commonly misidentified species, closely related or biochemically similar to Bcc and relevant in the context of cystic fibrosis microbiology. All Bcc strains clustered together, separated from non-Bcc strains. Within Bcc, most Bcc strains grouped in species specific clusters, except for Burkholderia anthina and Burkholderia pyrrocinia strains which constituted a single cluster. The present study demonstrates that MALDI-TOF MS is a powerful approach for the rapid identification of Bcc bacteria. PMID:18627778

Vanlaere, Elke; Sergeant, Kjell; Dawyndt, Peter; Kallow, Wibke; Erhard, Marcel; Sutton, Helen; Dare, Diane; Devreese, Bart; Samyn, Bart; Vandamme, Peter

2008-06-25

241

Monitoring of peptide acylation inside degrading PLGA microspheres by capillary electrophoresis and MALDI-TOF mass spectrometry.  

PubMed

The purpose of this research was to assess the acylation reactions of peptides, salmon calcitonin (sCT), human parathyroid hormone 1-34 (hPTH1-34) and leuprolide, in poly(lactic-co-glycolic acid) (PLGA) microspheres. Capillary electrophoresis (CE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used for determining and monitoring peptide acylation and quantitating acylation products in the degrading PLGA microspheres. In the degrading PLGA microspheres of sCT and hPTH1-34, the acylation products were observed and determined to be adducts with glycolic acid units from degradable PLGA polymer by MALDI-TOF MS. In the microsphere of leuprolide, however, the acylation product was not observed even after 28 days of incubation at the release medium, which represents the different stabilities among peptides according to the primary structure. As the leuprolide contains tyrosine and serine having hydroxyl group of nucleophilic amino acids, the acylation reaction of peptide is shown to be mainly due to the primary amino groups of N-terminus or lysine residue. The complementary use of CE and MALDI-TOF MS will be useful for searching the counter measures as well as determining the peptide acylation in the manufactured formulations on the market. PMID:14568410

Na, Dong Hee; Youn, Yu Seok; Lee, Sang Deuk; Son, Mi-Won; Kim, Won-Bae; DeLuca, Patrick P; Lee, Kang Choon

2003-10-30

242

Rapid and reliable MALDI-TOF mass spectrometry identification of Candida non-albicans isolates from bloodstream infections.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) fingerprinting has recently become an effective instrument for rapid microbiological diagnostics and in particular for identification of micro-organisms directly in a positive blood culture. The aim of the study was to evaluate a collection of 82 stored yeast isolates from bloodstream infection, by MALDI-TOF MS; 21 isolates were identified also directly from positive blood cultures and in the presence of other co-infecting micro-organisms. Of the 82 isolates grown on plates, 64 (76%) were correctly identified by the Vitek II system and 82 (100%) by MALDI-TOF MS; when the two methods gave different results, the isolate was identified by PCR. MALDI-TOF MS was unreliable in identifying two isolates (Candida glabrata and Candida parapsilosis) directly from blood culture; however, direct analysis from positive blood culture samples was fast and effective for the identification of yeast, which is of great importance for early and adequate treatment. PMID:23845229

Pulcrano, Giovanna; Iula, Dora Vita; Vollaro, Antonio; Tucci, Alessandra; Cerullo, Monica; Esposito, Matilde; Rossano, Fabio; Catania, Maria Rosaria

2013-07-09

243

Identification and classification of seafood-borne pathogenic and spoilage bacteria: 16S rRNA sequencing versus MALDI-TOF MS fingerprinting.  

PubMed

The present study aims to compare two molecular technologies, 16S rRNA sequencing and MALDI-TOF MS, for bacterial species identification in seafood. With this aim, 70 reference strains from culture collections, including important seafood-borne pathogenic and spoilage bacterial species, and 50 strains isolated from commercial seafood products, were analysed by both techniques. Genomic analysis only identified the species of 50% of the isolated strains, proving to be particularly poor at identifying members of the Pseudomonas and Bacillus genera. In contrast, MALDI-TOF MS fingerprinting identified 76% of the strains at the species level. The mass spectral data were submitted to the SpectraBank database (http://www.spectrabank.org), making this information available to other researchers. Furthermore, cluster analysis of the peak mass lists was carried out with the web application SPECLUST and the calculated groupings were consistent with results determined by a phylogenetic approach that is based on the 16S rRNA sequences. However, the MALDI-TOF MS analysis demonstrated more discriminating potential that allowed for better classification, especially for the Pseudomonas and Bacillus genera. This is of importance with respect to the varying pathogenic and spoilage character at the intragenus and intraspecies level. In this sense, MALDI-TOF MS demonstrated to be a competent bacterial typing tool that extends phenotypic and genotypic approaches, allowing a more ample classification of bacterial strains. PMID:23334977

Böhme, Karola; Fernández-No, Inmaculada C; Pazos, Manuel; Gallardo, José M; Barros-Velázquez, Jorge; Cañas, Benito; Calo-Mata, Pilar

2013-02-25

244

Analysis of herbicides in olive oil by liquid chromatography time-of-flight mass spectrometry.  

PubMed

The application of liquid chromatography time-of-flight mass spectrometry (LC/TOF-MS) for the identification and quantitation of four herbicides (simazine, atrazine, diuron, and terbuthylazine) in olive oil samples is reported here. The method includes a sample treatment step based on a preliminary liquid-liquid extraction followed by matrix solid-phase dispersion (MSPD) using aminopropyl as a sorbent material. A final cleanup step is performed with florisil using acetonitrile as an eluting solvent. The identification by LC/TOF-MS is accomplished with the accurate mass (and the subsequent generated empirical formula) of the protonated molecules [M + H]+, along with the accurate mass of the main fragment ion and the characteristic chlorine isotope cluster present in all of them. Accurate mass measurements are highly useful in this type of complex sample analyses since they allow us to achieve a high degree of specificity, often needed when other interferents are present in the matrix. The mass accuracy typically obtained is routinely better than 2 ppm. The sensitivity, linearity, precision, mass accuracy, and matrix effects are studied as well, illustrating the potential of this technique for routine quantitative analyses of herbicides in olive oil. Limits of detection (LODs) range from 1 to 5 microg/kg, which are far below the required maximum residue level (MRL) of 100 microg/kg for these herbicides in olive oil. PMID:16939302

García-Reyes, Juan F; Ferrer, Carmen; Thurman, E Michael; Fernandez-Alba, Amadeo R; Ferrer, Imma

2006-09-01

245

Analysis of Hanford-related Organics using Matrix-assisted Laser Desorption Ionization Time-of-flight Mass Spectrometry  

SciTech Connect

Matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry (MALDI/TOF-MS) was used for the analysis of low-molecular phosphate compounds found in Hanford tank wastes. The mass spectra of these compounds indicate protonated peaks as well as sodium adducts. Analytical methods presently utilized for the analysis of the phosphate-related organics are both time consuming and labor intensive. A promising alternative is MALDI/TOFMS. The MALDI process produces both positive and negative ions directly and very little sample is required. In addition,there is limited sample preparation and minimal hazardous waste production.

Campbell, James A. (BATTELLE (PACIFIC NW LAB)); Hess, Wayne P. (BATTELLE (PACIFIC NW LAB)); Lohman, Jeremy R. (ASSOC WESTERN UNIVERSITY); Goheen, Steven C. (BATTELLE (PACIFIC NW LAB))

2001-01-01

246

Proteomic biomarkers predicting lymph node involvement in serum of cervical cancer patients. Limitations of SELDI-TOF MS  

PubMed Central

Background Lymph node status is not part of the staging system for cervical cancer, but provides important information for prognosis and treatment. We investigated whether lymph node status can be predicted with proteomic profiling. Material & methods Serum samples of 60 cervical cancer patients (FIGO I/II) were obtained before primary treatment. Samples were run through a HPLC depletion column, eliminating the 14 most abundant proteins ubiquitously present in serum. Unbound fractions were concentrated with spin filters. Fractions were spotted onto CM10 and IMAC30 surfaces and analyzed with surface-enhanced laser desorption time of flight (SELDI-TOF) mass spectrometry (MS). Unsupervised peak detection and peak clustering was performed using MASDA software. Leave-one-out (LOO) validation for weighted Least Squares Support Vector Machines (LSSVM) was used for prediction of lymph node involvement. Other outcomes were histological type, lymphvascular space involvement (LVSI) and recurrent disease. Results LSSVM models were able to determine LN status with a LOO area under the receiver operating characteristics curve (AUC) of 0.95, based on peaks with m/z values 2,698.9, 3,953.2, and 15,254.8. Furthermore, we were able to predict LVSI (AUC 0.81), to predict recurrence (AUC 0.92), and to differentiate between squamous carcinomas and adenocarcinomas (AUC 0.88), between squamous and adenosquamous carcinomas (AUC 0.85), and between adenocarcinomas and adenosquamous carcinomas (AUC 0.94). Conclusions Potential markers related with lymph node involvement were detected, and protein/peptide profiling support differentiation between various subtypes of cervical cancer. However, identification of the potential biomarkers was hampered by the technical limitations of SELDI-TOF MS.

2012-01-01

247

Application of matrix-assisted laser desorption ionization-time of flight mass spectrometry for discrimination of laboratory-derived antibiotic-resistant bacteria.  

PubMed

The ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to discriminate laboratory-derived antibiotic-resistant bacterial strains of known genetic origin was examined. A computer-based cluster analysis of spectral data successfully discriminated the majority of single- as well as multiple-antibiotic-resistant Escherichia coli strains examined. Cluster analysis of Staphylococcus aureus strains with different levels of novobiocin resistance showed that as the degree of resistance increased similarity to the wild-type strain decreased. These results demonstrate that MALDI-TOF MS is capable of discriminating antibiotic-resistant bacterial strains and may have potential for differentiating bacterial strains with varying degrees of antibiotic-resistance. PMID:23037175

Muroi, Masashi; Shima, Keisuke; Igarashi, Masayuki; Nakagawa, Yasuyoshi; Tanamoto, Ken-ichi

2012-01-01

248

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Rapid Identification of Beta-Hemolytic Streptococci?  

PubMed Central

This study was undertaken to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of beta-hemolytic streptococci. We compared Bruker Biotyper 2.0 with Vitek2 coupled to the agglutination test. MALDI-TOF MS analysis of 386 beta-hemolytic streptococcal isolates yielded high-confidence identification to the species level for all 386 isolates. The Vitek2 gave high-confidence identification to the species level for 88% of Streptococcus agalactiae isolates (n = 269/306), 92% of Streptococcus pyogenes isolates (n = 48/52), and 39% of isolates of Streptococcus dysgalactiae serogroups C and G (n = 11/28).

Cherkaoui, Abdessalam; Emonet, Stephane; Fernandez, Jose; Schorderet, Didier; Schrenzel, Jacques

2011-01-01

249

Identification of anaerobic bacteria by Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry with on-plate formic acid preparation.  

PubMed

Identification of anaerobic bacteria using phenotypic methods is often time-consuming; methods such as 16S rRNA gene sequencing are costly and may not be readily available. We evaluated 253 clinical isolates of anaerobic bacteria using the Bruker MALDI Biotyper (Bruker Daltonics, Billerica, MA) matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system with a user-supplemented database and an on-plate formic acid-based preparation method and compared results to those of conventional identification using biochemical testing or 16S rRNA gene sequencing. A total of 179 (70.8%) and 232 (91.7%) isolates were correctly identified to the species and genus levels, respectively, using manufacturer-recommended score cutoffs. MALDI-TOF MS offers a rapid, inexpensive method for identification of anaerobic bacteria. PMID:23254126

Schmitt, Bryan H; Cunningham, Scott A; Dailey, Aaron L; Gustafson, Daniel R; Patel, Robin

2012-12-19

250

Analysis of Whole Bacterial Cells by Flow Field-Flow Fractionation and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry  

SciTech Connect

The purpose of this study is to develop a novel bacterial analysis method by coupling the flow field-flow fractionation (flow FFF) separation technique with detection by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The composition of carrier liquid used for flow FFF was selected based on retention of bacterial cells and compatibility with the MALDI process. The feasibility of coupling flow FFF and MALDI-TOF MS was demonstrated for P. putida and E. coli. Fractions of the whole cells were collected after separation by FFF and further analyzed by MALDI-MS. Each fraction, collected over different time intervals, corresponded to different sizes and possibly different growth stages of bacteria. The bacterial analysis by flow FFF/MALDI-TOF MS was completed within 1 hour with only preliminary optimization of the process.

Lee, Hookeun; Williams, Kim R.; Wahl, Karen L.; Valentine, Nancy B.

2003-06-01

251

Rapid identification of Gram-negative organisms from blood culture bottles using a modified extraction method and MALDI-TOF mass spectrometry.  

PubMed

The application of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry (MS) directly to blood culture broth has potential to identify bloodstream infection earlier and facilitate timely management. We prospectively tested a novel, rapid, and inexpensive in-house spin-lysis protocol with formic acid extraction and compared MALDI-TOF MS identification of Gram-negative bacteria with traditional phenotypic methods (Phoenix™) directly from 318 BACTEC™ (Becton Dickinson, Franklin Lakes, USA) blood cultures. The MS score was ?1.7 in 268 (91.8%) monomicrobial broths, with concordance to genus and species level of 100% and 97.0%, respectively. MALDI-TOF MS still has limited capacity to detect all species in polymicrobial broths. PMID:23891220

Gray, Timothy J; Thomas, Lee; Olma, Tom; Iredell, Jonathan R; Chen, Sharon C-A

2013-07-23

252

Gold Ion-Angiotensin Peptide Interaction by Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Stimulated by the interest in developing gold compounds for treating cancer, gold ion-angiotensin peptide interactions are investigated by mass spectrometry. Under the experimental conditions used, the majority of gold ion-angiotensin peptide complexes contain gold in the oxidation states I and III. Both ESI-MS and MALDI-TOF MS detect singly/multiply charged ions for mononuclear/multinuclear gold-attached peptides, which are represented as [peptide + a Au(I) + b Au(III) + (e - a -3b) H]e+, where a,b ? 0 and e is charge. ESI-MS data shows singly/multiply charged ions of Au(I)-peptide and Au(III)-peptide complexes. This study reveals that MALDI-TOF MS mainly detects singly charged Au(I)-peptide complexes, presumably due to the ionization process. The electrons in the MALDI plume seem to efficiently reduce Au(III) to Au(I). MALDI also tends to enhance the higher polymeric forms of gold-peptide complexes regardless of the laser power used. Collision-induced dissociation experiments of the mononuclear and dinuclear gold-attached peptide ions for angiotensin peptides show that the gold ion (a soft acid) binding sites are in the vicinity of Cys (a soft ligand), His (a major anchor of peptide for metal ion chelation), and the basic residue Arg. Data also suggests that the abundance of gold-attached peptides increases with higher gold concentration until saturation, after which an increase in gold ion concentration leads to the aggregation and/or precipitation of gold-bound peptides.

Lee, Jenny; Jayathilaka, Lasanthi P.; Gupta, Shalini; Huang, Jin-Sheng; Lee, Bao-Shiang

2012-05-01

253

Identification of two-dimensionally separated human cerebrospinal fluid proteins by N-terminal sequencing, matrix-assisted laser desorption/ionization--mass spectrometry, nanoliquid chromatography-electrospray ionization-time of flight-mass spectrometry, and tandem mass spectrometry.  

PubMed

Optimal application of biological mass spectrometry (MS) in combination with two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) of human cerebrospinal fluid (CSF) can lead to the identification of new potential biological markers of neurological disorders. To this end, we analyzed a number of 2-D PAGE protein spots in a human CSF pool using spot co-localization, N-terminal sequencing, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and nanoliquid chromatography-electrospray ionization-time of flight-mass spectrometry (nanoLC-ESI-TOF-MS) with tandem MS switching. Our constructed CSF master contained 469 spots after image analysis and processing of 2-D gels. Upon visual inspection of our CSF master with the CSF pattern available on the ExPASy server, it was possible to locate and annotate 15 proteins. N-terminal sequence analysis and MALDI-MS peptide mass fingerprint analysis of both silver- and Coomassie Brilliant Blue (CBB) G-250-stained protein spots after in situ trypsin digest not only confirmed nine of the visually annotated spots but additionally resolved the identity of another 13 spots. Six of these proteins were not annotated on the 2-D ExPASy map: complement C3 alpha-chain (1321-1663), complement factor B, cystatin C, calgranulin A, hemoglobin beta-chain, and beta-2-microglobulin. It was clear that MALDI-MS identification from CBB G-250-stained, rather than from silver-stained, spots was more successful. In cases where no N-terminal sequence and/or no clear MALDI-MS result was available, nanoLC-ESI-TOF-MS and tandem MS automated switching was used to clarify and/or identify these protein spots by generating amino acid sequence tags. In addition, enrichment of the concentration of low-abundant proteins on 2-D PAGE was obtained by removal of albumin and immunoglobulins from the CSF pool using affinity chromatography. Subsequent analysis by 2-D PAGE of the fractionated CSF pool showed various new silver-stainable protein spots, of which four were identified by nanoLC-ESI-TOF-MS and tandem MS switching. No significant homology was found in either protein or DNA databases, indicating than these spots were unknown proteins. PMID:10892737

Raymackers, J; Daniels, A; De Brabandere, V; Missiaen, C; Dauwe, M; Verhaert, P; Vanmechelen, E; Meheus, L

2000-06-01

254

Proteomic study of serum using gel chromatography and MALDI-TOF MS reveals diagnostic biomarkers in male patients with liver-cancer  

NASA Astrophysics Data System (ADS)

Human serum has been widely employed clinically for diagnosing various fatal diseases. However, the concentration of most proteins in human serum is too low to be directly measured using normal analytical methods. In order to obtain reliable analytical results from proteomic analysis of human serum, appropriate sample preparation is essential. A combined off-line analytical technique of gel chromatography and matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF MS) has been successfully established to separate proteins for MS analysis. Using these combined techniques, 176 mass signal peaks of proteins/peptides were found in 6 of 18 fractions from normal male serum (NMS) in the presence of buffer consisting of NH4HCO3 and acetonitrile. A simple gel chromatography column packed with Sephadex G-50 removed most signal-suppressing compounds such as salts and high abundance proteins (HAP). The molecular mass to charge (m/z) ratios of differential peptides revealed in serum of male patient with liver-cancer (LCMPS) compared to NMS were 5365, 5644 and 6462, and these peptides can be used as biomarkers to clinically diagnose liver-cancer. The simple and convenient chromatographic method described here is not only superior to recently described HPLC separation for MS analysis, but also reveals many novel and significant serum biomarkers for the clinical diagnosis of various diseases.

Zeng, Xin-Hua; Huang, He-Qing; Chen, Dong-Shi; Jin, Hong-Wei; Huang, Hui-Ying

2007-03-01

255

Microorganism Identification Based On MALDI-TOF-MS Fingerprints  

NASA Astrophysics Data System (ADS)

Advances in MALDI-TOF mass spectrometry have enabled the ­development of a rapid, accurate and specific method for the identification of bacteria directly from colonies picked from culture plates, which we have named the MALDI Biotyper. The picked colonies are placed on a target plate, a drop of matrix solution is added, and a pattern of protein molecular weights and intensities, "the protein fingerprint" of the bacteria, is produced by the MALDI-TOF mass spectrometer. The obtained protein mass fingerprint representing a molecular signature of the microorganism is then matched against a database containing a library of previously measured protein mass fingerprints, and scores for the match to every library entry are produced. An ID is obtained if a score is returned over a pre-set threshold. The sensitivity of the techniques is such that only approximately 104 bacterial cells are needed, meaning that an overnight culture is sufficient, and the results are obtained in minutes after culture. The improvement in time to result over biochemical methods, and the capability to perform a non-targeted identification of bacteria and spores, potentially makes this method suitable for use in the detect-to-treat timeframe in a bioterrorism event. In the case of white-powder samples, the infectious spore is present in sufficient quantity in the powder so that the MALDI Biotyper result can be obtained directly from the white powder, without the need for culture. While spores produce very different patterns from the vegetative colonies of the corresponding bacteria, this problem is overcome by simply including protein fingerprints of the spores in the library. Results on spores can be returned within minutes, making the method suitable for use in the "detect-to-protect" timeframe.

Elssner, Thomas; Kostrzewa, Markus; Maier, Thomas; Kruppa, Gary

256

Clinical and Microbiological Features of a Cystic Fibrosis Patient Chronically Colonized with Pandoraea sputorum Identified by Combining 16S rRNA Sequencing and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Clonal isolates identified as various nonfermentative Gram-negative bacilli over a 5-year period from sputum cultures of a 30-year-old cystic fibrosis patient were successfully reidentified as Pandoraea sputorum by combining 16S rRNA sequencing and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Decreased lung function improved after 1 year of azithromycin and inhaled 7%-hypertonic saline treatment.

Fernandez-Olmos, A.; Morosini, M. I.; Lamas, A.; Garcia-Castillo, M.; Garcia-Garcia, L.; Maiz, L.

2012-01-01

257

Clinical and microbiological features of a cystic fibrosis patient chronically colonized with Pandoraea sputorum identified by combining 16S rRNA sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry.  

PubMed

Clonal isolates identified as various nonfermentative Gram-negative bacilli over a 5-year period from sputum cultures of a 30-year-old cystic fibrosis patient were successfully reidentified as Pandoraea sputorum by combining 16S rRNA sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Decreased lung function improved after 1 year of azithromycin and inhaled 7%-hypertonic saline treatment. PMID:22170922

Fernández-Olmos, A; Morosini, M I; Lamas, A; García-Castillo, M; García-García, L; Cantón, R; Máiz, L

2011-12-14

258

A rapid method for simultaneous determination of 14 phenolic compounds in Radix Puerariae using microwave-assisted extraction and ultra high performance liquid chromatography coupled with diode array detection and time-of-flight mass spectrometry  

Microsoft Academic Search

A microwave-assisted extraction (MAE) and ultra high performance liquid chromatography coupled with diode array detection and time-of-flight mass spectrometry (UHPLC-DAD-TOF-MS) method was developed for simultaneous determination of 14 phenolic compounds in the root of Pueraria lobata (Wild.) Ohwi and Pueraria thomsonii Benth. Operational conditions of MAE were optimized by central composite design (CCD). The optimized result was 65% ethanol as

G. Du; H. Y. Zhao; Q. W. Zhang; G. H. Li; F. Q. Yang; Y. Wang; Y. C. Li

2010-01-01

259

Identification of biotinylated lysine residues in the photoprotein aequorin by matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry peptide mapping after lysine-specific endopeptidase digestion  

Microsoft Academic Search

A method for identifying modified lysine residues in a protein, using lysine-specific endopeptidase treatment followed by matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) peptide mapping, is described. As a model protein, the photoprotein aequorin was chosen and the N-hydroxysuccinimide ester of biotin was employed to chemically modify the lysine residues. After digestion with lysine-specific endopeptidase, the biotinylated residues of an

Satoshi Inouye; Mitsuhiro Nakamura

2003-01-01

260

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry in Comparison to 16S rRNA Gene Sequencing for Species Identification of Nonfermenting Bacteria  

Microsoft Academic Search

Nonfermenting bacteria are ubiquitous environmental opportunists that cause infections in humans, especially compromised patients. Due to their limited biochemical reactivity and different morphotypes, misidentification by classical phenotypic means occurs frequently. Therefore, we evaluated the use of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for spe- cies identification. By using 248 nonfermenting culture collection strains composed of 37 genera most

A. Mellmann; J. Cloud; T. Maier; U. Keckevoet; I. Ramminger; P. Iwen; J. Dunn; G. Hall; D. Wilson; P. LaSala; M. Kostrzewa; D. Harmsen

2008-01-01

261

Identification of parotid salivary biomarkers in Sjogren's syndrome by surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry and two-dimensional difference gel electrophoresis  

Microsoft Academic Search

Objectives. To identify the most significant salivary biomarkers in Sjogren's syndrome (SS) using proteomic methods. Methods. Parotid saliva from 20 non-SS subjects and 41 primary SS patients was analysed. Protein expression profiles for each sample were generated by surface-enhanced laser desorption\\/ionization time-of-flight-mass spectrometry (SELDI-TOF-MS). Mean peak intensities of SS patients and non-SS subjects were compared by univariate analyses. Samples pooled

O. H. Ryu; J. C. Atkinson; G. T. Hoehn; G. G. Illei; T. C. Hart

2006-01-01

262

Comparison of the accuracy of matrix-assisted laser desorption ionization-time of flight mass spectrometry with that of other commercial identification systems for identifying Staphylococcus saprophyticus in urine.  

PubMed

Among 30 urinary isolates of Staphylococcus saprophyticus identified by sequencing methods, the rate of accurate identification was 100% for Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 86.7% for the Phoenix PID and Vitek 2 GP systems, 93.3% for the MicroScan GP33 system, and 46.7% for the BBL CHROMagar Orientation system. PMID:23390286

Lee, Tai-Fen; Lee, Hao; Chen, Chung-Ming; Du, Shin-Hei; Cheng, Ya-Chih; Hsu, Chen-Ching; Chung, Meng-Yu; Teng, Shih-Hua; Teng, Lee-Jene; Hsueh, Po-Ren

2013-02-06

263

Establishment of a quantitative, qualitative, and high-throughput analysis of sulfatides from small amounts of sera by matrix-assisted laser desorption ionization–time of flight mass spectrometry  

Microsoft Academic Search

Based on our previous measurements of sulfatides, we further developed a quantitative, qualitative, and high-throughput analytical method for serum sulfatides as forms of lysosulfatides by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Using 0.1N NaOH in 90% MeOH for saponification instead of absolute MeOH, as previously used, we succeeded in eliminating the formation of lysosulfatide artifacts, facilitating much

Gang Li; Rui Hu; Yuji Kamijo; Takero Nakajima; Toshifumi Aoyama; Teruo Inoue; Koichi Node; Reiji Kannagi; Mamoru Kyogashima; Atsushi Hara

2007-01-01

264

Determination of Oligopeptide Diversity within a Natural Population of Microcystis spp. (Cyanobacteria) by Typing Single Colonies by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

Microsoft Academic Search

Besides the most prominent peptide toxin, microcystin, the cyanobacteria Microcystis spp. have been shown to produce a large variety of other bioactive oligopeptides. We investigated for the first time the oligopeptide diversity within a natural Microcystis population by analyzing single colonies directly with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The results demonstrate a high diversity of

JUTTA FASTNER; MARCEL ERHARD; HANS VON DOHREN

2001-01-01

265

Surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry: serum protein profiling in seminoma patients  

Microsoft Academic Search

Purpose  Surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS) allows rapid protein profiling\\u000a of complex biological mixtures. We analyzed testicular germ cell cancer serum samples to differentiate between cancer and\\u000a controls with a special focus on ?-hCG-negative seminomas.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Proteomic spectra were generated by the ProteinChip® system and analyzed by the proteomic platform “proteomic.net”. For statistical analysis, an artificial intelligence learning

Romy Strenziok; Stefan Hinz; Christian Wolf; Tim Conrad; Hans Krause; Kurt Miller; Mark Schrader

2010-01-01

266

[Simultaneous determination of 10 unapproved sedative drugs in feeds by ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry].  

PubMed

A new analytical method using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was developed for screening and confirmation of 10 unapproved sedative drugs in feeds. The samples were extracted using the solution of methanol-0.1 mol/L HCl (9:1, v/v), and the extracts were centrifuged and then directly purified through MCX cartridges. The identification and detection were achieved in positive electrospray ionization (ESI) mode using Q-TOF-MS. The potential of UPLC-Q-TOF MS for confirmatory analysis was shown by determining the accurate mass of all the compounds and fragment ions upon collision-induced-dissociation (CID) at different energies. The extra mass measurement errors for all the sedative drugs were found to be within 5 ppm. The calibration graphs were linear in the concentration range of 5-100 microg/L with the correlation coefficients more than 0.99 for the 10 drugs. The limits of quantification (LOQ, S/N = 10) were 8 microg/kg for nitrazepam, zolpidem and thioridazine; 10 microg/kg for thriazolam, estazolam, diazepam, promethazine, chlorpromazine and midazolam; 20 microg/kg for clozapine. The recoveries for all the compounds in feeds were 60.6%-108.5% with the relative standard deviations less than 10% at the spiked levels of LOQ, 2LOQ and 4LOQ. PMID:22934407

Xu, Chengbao; Suo, Ran; Zhang, Feng; Chu, Xiaogang; Ding, Fei; Ling, Yun; Yang, Minli; Sun, Li

2012-05-01

267

Laser TOF-MS for In Situ Analysis of Outer Planetary Moons and Small Bodies  

NASA Astrophysics Data System (ADS)

The in-depth exploration of the moons and small bodies of the outer solar system represents an enormously exciting and challenging long-term vision for planetary science. Such missions will require increasingly sophisticated and miniaturized robotic analytical tools for in situ sampling and composition studies. Surface and sub-surface rock, ice, and fine samples will be accessed and studied on a range of spatial scales. Microscopy, mineralogy, and molecular/organic, elemental, and isotopic analyses are all needed to address in situ goals. These techniques must work as an efficient suite to provide complementary and cross-calibrated data. Toward such a suite, we are developing miniature time-of-flight mass spectrometers (TOF-MS) for microanalysis of minimally prepared samples. An adjustable-energy pulsed laser volatilizes and ionizes material from a small region on the sample. Ions enter the instrument and are detected at a sequence of times proportional to the square root of their mass-to-charge ratios. Thus, each laser pulse produces a complete mass spectrum (in less than 50 microseconds). These instruments can now be significantly miniaturized while maintaining high performance. Additional information is contained in the original extended abstract.

Brinckerhoff, W. B.; Cornish, T. J.; Cheng, A. F.; McEntire, R. W.

2001-01-01

268

Mass Spectrometry as a Powerful Analytical Technique for the Structural Characterization of Synthesized and Natural Products  

NASA Astrophysics Data System (ADS)

Mass spectrometry is an important tool for the identification and structural elucidation of natural and synthesized compounds. Its high sensitivity and the possibility of coupling liquid chromatography with mass spectrometry detection make it a technique of choice for the investigation of complex mixtures like raw natural extracts. The mass spectrometer is a universal detector that can achieve very high sensitivity and provide information on the molecular mass. More detailed information can be subsequently obtained by resorting to collision-induced dissociation tandem mass spectrometry (CID-MS/MS). In this review, the application of mass spectrometric techniques for the identification of natural and synthetic compounds is presented. The gas-phase fragmentation patterns of a series of four natural flavonoid glycosides, three synthesized benzodiazepines and two synthesized quinoxalinone derivatives were investigated using electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry techniques. Exact accurate masses were measured using a modorate resolution quadrupole orthogonal time-of-flight QqTOF-MS/MS hybrid mass spectrometer instrument. Confirmation of the molecular masses and the chemical structures of the studied compounds were achieved by exploring the gas-phase breakdown routes of the ionized molecules. This was rationalized by conducting low-energy collision CID-MS/MS analyses (product ion- and precursor ion scans) using a conventional quadrupole hexapole-quadrupole (QhQ) tandem mass spectrometer.

Es-Safi, Nour-Eddine; Essassi, El Mokhtar; Massoui, Mohamed; Banoub, Joseph

269

Fourier Transform Mass Spectrometry  

PubMed Central

This article provides an introduction to Fourier transform-based mass spectrometry. The key performance characteristics of Fourier transform-based mass spectrometry, mass accuracy and resolution, are presented in the view of how they impact the interpretation of measurements in proteomic applications. The theory and principles of operation of two types of mass analyzer, Fourier transform ion cyclotron resonance and Orbitrap, are described. Major benefits as well as limitations of Fourier transform-based mass spectrometry technology are discussed in the context of practical sample analysis, and illustrated with examples included as figures in this text and in the accompanying slide set. Comparisons highlighting the performance differences between the two mass analyzers are made where deemed useful in assisting the user with choosing the most appropriate technology for an application. Recent developments of these high-performing mass spectrometers are mentioned to provide a future outlook.

Scigelova, Michaela; Hornshaw, Martin; Giannakopulos, Anastassios; Makarov, Alexander

2011-01-01

270

Resolving pathways of interaction of covalent inhibitors with the active site of acetylcholinesterases: MALDI-TOF/MS analysis of various nerve agent phosphyl adducts.  

PubMed

Understanding reaction pathways of phosphylation, reactivation, and "aging" of AChE with toxic organophosphate compounds is both a biochemical and a pharmacological challenge. Here we describe experiments which allowed to resolve some of the less well understood reaction pathways of phosphylation and "aging" of acetylcholinesterase (AChE) involving phosphoroamidates (P-N agents) such as tabun or the widely used pesticide methamidophos. Tryptic digests of phosphylated AChEs (from human and Torpedo californica), ZipTip peptide fractionation and matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF/MS) enabled reproducible signal enrichment of the isotopically resolved peaks of organophosphoroamidate conjugates of the AChE active site Ser peptides. For tabun and its hexadeuterio analogue, we find, as expected, that the two phosphoramidate adducts of the active site peptide differ by 6.05 mass units but following aging we find that the two corresponding phospho-peptides have identical molecular weights. We further show that the aging product of paraoxon-AChE adduct is identical to the aging product of the tabun-AChE conjugate. These results unequivocally demonstrate that the pathway of aging of tabun adducts of the human or the Torpedo californica AChEs proceeds through P-N bond scission. For methamidophos, we show that phosphylation of AChE involves elimination of the thiomethyl moiety and that the spontaneous reactivation of the resulting organophosphate adduct generates the phosphorus free AChE active site Ser-peptide. PMID:11453739

Elhanany, E; Ordentlich, A; Dgany, O; Kaplan, D; Segall, Y; Barak, R; Velan, B; Shafferman, A

2001-07-01

271

Rapid characterization of chemical constituents and rats metabolites of the traditional Chinese patent medicine Gegen-Qinlian-Wan by UHPLC/DAD/qTOF-MS.  

PubMed

Gegen-Qinlian-Wan (GQW) is a popular traditional Chinese patent medicine for the treatment of diarrhea. It is composed of four herbal medicines, Puerariae Radix, Scutellariae Radix, Coptidis Rhizoma, and Glycyrrhizae Radix. In this study, a rapid and sensitive method based on ultra high-performance liquid chromatography coupled with diode-array detection and quadrupole time-of-flight mass spectrometry (UHPLC-DAD-qTOF-MS) was established to characterize the chemical constituents and rats metabolites of GQW. Samples were separated on an Agilent Zorbax Eclipse Plus-C(18) column (100 mm × 2.1 mm, 1.8 ?m) by gradient elution using acetonitrile and water containing 0.1% formic acid as the mobile phase. On the basis of UV and qTOF high-accuracy mass spectral analysis, a total of 62 compounds were identified or tentatively characterized from GQW, including 42 flavonoids, 8 alkaloids, 6 triterpenoids, 3 phenylethanoid glycosides, and 3 other types. Among them, 27 compounds were confirmed by comparing with reference standards. Furthermore, metabolites in rats plasma and urine after oral administration of GQW were also analyzed. A total of 42 compounds were identified, including 29 prototypes and 13 metabolites through metabolic pathways of demethylation, methylation, hydrolysis, sulfate conjugation, and glucuronide conjugation. Glucuronidated flavonoids were the main constituents in the plasma, and were then transformed into aglycones and excreted from urine. This is the first systematic study on the chemical constituents and metabolic profiling of GQW. PMID:23146232

Miao, Wen-juan; Wang, Qing; Bo, Tao; Ye, Min; Qiao, Xue; Yang, Wen-zhi; Xiang, Cheng; Guan, Xiang-yu; Guo, De-an

2012-09-28

272

GC-EI-TOF-MS analysis of in vivo carbon-partitioning into soluble metabolite pools of higher plants by monitoring isotope dilution after 13CO 2 labelling  

Microsoft Academic Search

The established GC-EI-TOF-MS method for the profiling of soluble polar metabolites from plant tissue was employed for the kinetic metabolic phenotyping of higher plants. Approximately 100 typical GC-EI-MS mass fragments of trimethylsilylated and methoxyaminated metabolite derivatives were structurally interpreted for mass isotopomer analysis, thus enabling the kinetic study of identified metabolites as well as the so-called functional group monitoring of

Jan Huege; Ronan Sulpice; Yves Gibon; Jan Lisec; Karin Koehl; Joachim Kopka

2007-01-01

273

Comprehensive chemical profiling of guizhi fuling capsule by the combined use of gas chromatography-mass spectrometry with a deconvolution software and rapid-resolution liquid chromatography quadrupole time-of-flight tandem mass spectrometry.  

PubMed

Herbal formulations are complex natural mixtures. Researchers usually tend to focus more on analysis of nonvolatile components but pay less attention to volatile compounds. In this study, an analytical strategy combining two approaches was established for comprehensive analysis of herbal formulations. Guizhi Fuling capsule (GFC), a drug approved by the FDA to enter phase II clinical trial for treatment of primary dysmenorrhea, was taken as a case for analysis. Gas chromatography-mass spectrometry (GC-MS) with automated mass spectral deconvolution and identification system (AMDIS) led to rapid identification of 48 volatile components including four acetophenones, three fatty acid esters, 13 phenylpropanoids and 19 sesquiterpenes. Most of them were found from Guizhi. The volatile oils of Guizhi have been proved to exhibit many pharmacological activities. This is helpful in understanding the pharmacological mechanism of GFC. Furthermore, AMDIS turned out to be efficient and reliable for analysis of complex herbal formulations. Rapid-resolution liquid chromatography (RRLC) coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF MS/MS) allowed the identification of 70 nonvolatile components including six acetophenones, 12 galloyl glucoses, 31 monoterpene glycosides, three phenols and 12 triterpene acids. Fragmentation behaviors of assigned components, especially triterpene acids, which are hard to identify by low-resolution MS, were first investigated by TOF MS/MS. Characteristic ions and typical loss of assigned triterpene acids were summarized. Combinatorial use of GC-MS-AMDIS and RRLC-ESI-Q-TOF MS/MS could be of great help in global qualitative analysis of GFC, as well as other herbal products. PMID:22297903

Wang, Ya-Qiong; Qi, Lian-Wen; Aa, Jiye; Wang, Guang-Ji; Gao, Wen; Cheng, Shu-Jie; Wang, Zhen-Zhong; Xiao, Wei; Li, Ping

2012-02-02

274

Environmental Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Environmental mass spectrometry is an important branch of science because it provides many of the data that underlie policy decisions that can directly influence the health of people and ecosystems. Environmental mass spectrometry is currently undergoing rapid development. Among the most relevant directions are a significant broadening of the lists of formally targeted compounds; a parallel interest in nontarget chemicals; an increase in the reliability of analyses involving accurate mass measurements, tandem mass spectrometry, and isotopically labeled standards; and a shift toward faster high-throughput analysis, with minimal sample preparation, involving various approaches, including ambient ionization techniques and miniature instruments. A real revolution in analytical chemistry could be triggered with the appearance of robust, simple, and sensitive portable mass spectrometers that can utilize ambient ionization techniques. If the cost of such instruments is reduced to a reasonable level, mass spectrometers could become valuable household devices.

Lebedev, Albert T.

2013-06-01

275

Environmental mass spectrometry.  

PubMed

Environmental mass spectrometry is an important branch of science because it provides many of the data that underlie policy decisions that can directly influence the health of people and ecosystems. Environmental mass spectrometry is currently undergoing rapid development. Among the most relevant directions are a significant broadening of the lists of formally targeted compounds; a parallel interest in nontarget chemicals; an increase in the reliability of analyses involving accurate mass measurements, tandem mass spectrometry, and isotopically labeled standards; and a shift toward faster high-throughput analysis, with minimal sample preparation, involving various approaches, including ambient ionization techniques and miniature instruments. A real revolution in analytical chemistry could be triggered with the appearance of robust, simple, and sensitive portable mass spectrometers that can utilize ambient ionization techniques. If the cost of such instruments is reduced to a reasonable level, mass spectrometers could become valuable household devices. PMID:23527549

Lebedev, Albert T

2013-02-28

276

Rapid identification of microbial VOCs from tobacco molds using closed-loop stripping and gas chromatography/time-of-flight mass spectrometry.  

PubMed

Several microbial volatile organic compounds (MVOCs) that can serve as potential chemical markers for microbial contamination in tobacco have been identified. Four different fungal species, Aspergillus niger (AN), A. ornatus (AO), Pencillium chrysogenum (PC) and Rhizopus stolonifer (RS), commonly reported in moldy tobacco were cultured and screened for MVOCs. Because the MVOCs emitted by a microbial species are substrate specific, the fungal strains were separately grown on potato dextrose agar (PDA) and tobacco products. MVOCs from the mold cultures grown on PDA and tobacco products were extracted using closed-loop stripping analysis (CLSA) and identified by gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS). Some of the prominent tobacco mold markers identified by this method include: 1-octen-3-ol; 2-octen-1-ol; 2-methyl-1-butanol; 3-methyl-1-butanol; 1-octene and 2-pentanone. In particular, 1-octen-3-ol was detected in all the mold cultures and moldy tobacco samples analyzed. Olfactory evaluation of 1-octen-3-ol indicated a characteristic musty odor and the odor threshold was determined to be approximately 200 ng/ml. The limits of detection for 1-octen-3-ol using GC/TOF-MS and GC/mass selective detector (MSD) in the full-scan mode and selected ion monitoring (SIM) mode were investigated. The CLSA-GC/TOF-MS demonstrates a fast, sensitive and semi-quantitative analytical technique for screening tobacco materials for the presence of mold via chemical markers of microbial contamination. PMID:15517467

Meruva, N K; Penn, J M; Farthing, D E

2004-10-26

277

Determination of Bioactive Peptide Molecular Mass Using Electrospray and Matrix Assisted Laser Desorption Ionization Mass Spectrometry.  

National Technical Information Service (NTIS)

Twelve bioactive peptides, ranging in molecular masses from 600 and 4500 u, were selected for ESI-MS and MALDI-TOF-MS analysis in order to assess the spectrometric data that could be accessed for rapid CB screening purposes. Monoisotopic molecular mass da...

P. A. D'Agostino J. R. Hancock L. R. Provost J. A. Tornes Y. Dai

1998-01-01

278

Mass Spectrometry for the Masses  

ERIC Educational Resources Information Center

|A simple, qualitative experiment is developed for implementation, where the gas chromatography-mass spectrometry (GC-MS) plays an important role, into the laboratory curriculum of a chemistry course designed for nonscience majors. This laboratory experiment is well suited for the students as it helps them to determine the validity of their…

Persinger, Jared D.; Hoops, Geoffrey, C.; Samide, Michael J.

2004-01-01

279

Identification of Gram-positive cocci by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry: comparison of different preparation methods and implementation of a practical algorithm for routine diagnostics.  

PubMed

This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods. PMID:23554198

Schulthess, Bettina; Brodner, Katharina; Bloemberg, Guido V; Zbinden, Reinhard; Böttger, Erik C; Hombach, Michael

2013-04-03

280

Ultra-performance LC/TOF MS analysis of medicinal Panax herbs for metabolomic research.  

PubMed

In this study, metabolite profiling of five medicinal Panax herbs including Panax ginseng (Chinese ginseng), Panax notoginseng (Sanchi), Panax japonicus (Rhizoma Panacis Majoris), Panax quinquefolium L. (American ginseng), and P. ginseng (Korean ginseng) were performed using ultra-performance LC-quadrupole TOF MS (UPLC-QTOFMS) and multivariate statistical analysis technique. Principal component analysis (PCA) of the analytical data showed that the five Panax herbs could be separated into five different groups of phytochemicals. The chemical markers such as ginsenoside Rf, 20(S)-pseudoginsenoside F11, malonyl gisenoside Rb1, and gisenoside Rb2 accountable for such variations were identified through the loadings plot of PCA, and were identified tentatively by the accurate mass of TOFMS and partially verified by the available reference standards. Results from this study indicate that the proposed method is reliable for the rapid analysis of a group of metabolites present in herbal medicines and other natural products and applicable in the differentiation of complex samples that share similar chemical ingredients. PMID:18338405

Xie, Guoxiang; Plumb, Robert; Su, Mingming; Xu, Zhaohui; Zhao, Aihua; Qiu, Mingfeng; Long, Xiangbao; Liu, Zhong; Jia, Wei

2008-04-01

281

Rapid and sensitive analysis of multiple bioactive constituents in Compound Danshen preparations using LC-ESI-TOF-MS.  

PubMed

By fully optimizing the separation and analytical conditions, a rapid-resolution LC (RRLC, 1.8 microm particle size) coupled with TOF-MS method was developed and validated for multiple compounds analysis of traditional Chinese medicinal compound preparations (TCMCPs). As a typical example, determination of Compound Danshen preparations (CDPs, mainly comprising Salvia miltiorrhiza and Panax notoginseng), was improved on three groups of bioactive constituents (phenolic acids, diterpenoids, and saponins). LODs down to 1.2 pg, permitting very good separation of 20 analytes and 3 internal standards (ISs) in 17 min, represented an approximate five-fold reduction of time compared to conventional HPLC. Unequivocal identification of target compounds in CDPs was based on accurate mass measurement of ions, and comparison of retention performance with available standards. Quantitation was carried out using the narrow window extracted ion chromatograms (XICs) of each compound with an interference-free baseline (using a +/-0.02 Da window) yielding good linearity of response (r(2) >0.9940), and excellent precision of retention time (t(R)) both interday (RSD, 0.01-0.19%) and intraday (RSD, 0.02-1.08%). The acceptable recoveries obtained were in the range of 77.69-113.8%. The results demonstrated the robustness and applicability of RRLC-TOF-MS for multicomponents analysis in TCMCPs with diverse chemical compositions and properties. PMID:18763250

Xia, Li; Liu, Hai-Ling; Li, Ping; Zhou, Jian-Liang; Qi, Lian-Wen; Yi, Ling; Chen, Jun

2008-10-01

282

Detection of sheep and goat milk adulterations by direct MALDI-TOF MS analysis of milk tryptic digests.  

PubMed

In dairy field, one of the most common frauds is the adulteration of higher value types of milk (sheep's and goat's) with milk of lower value (cow's milk). This illegal practice has an economic advantage for milk producers and poses a threat for consumers' health because of the presence of hidden allergens as, for example, cow milk proteins, in particular, ?(s1)-casein and ?-lactoglobulin. The urgent need of sensitive techniques to detect this kind of fraud brought to the development of chromatographic, immunoenzymatic, electrophoretic and mass spectrometric assays. In the current work, we present a fast, reproducible and sensitive method based on the direct matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) MS analysis of milk tryptic digests for the detection of milk adulteration by evaluating specie-specific markers in the peptide profiles. Several pure raw and commercial milk samples and binary mixtures containing cows' and goats', cows' and sheep's and goats' and sheep's milk (concentrations of each milk varied from 0% to 100%) were prepared, and tryptic digests were analyzed by MALDI-TOF MS. The use of the new MALDI matrix ?-cyano-4-chlorocinnamic acid allowed to detect cow and goat milk peptide markers up to 5% level of adulteration. Finally, from preliminary data, it seems that the strategy could be successfully applied also to detect similar adulterations in cheese samples. PMID:22972782

Calvano, Cosima Damiana; De Ceglie, Cristina; Monopoli, Antonio; Zambonin, Carlo Giorgio

2012-09-01

283

Rapid determination of total solanesol in tobacco leaf by ultrasound-assisted extraction with RP-HPLC and ESI-TOF/MS.  

PubMed

A reliable and rapid method based on high-performance liquid chromatography (HPLC-UV) and positive ion electrospray-time of flight mass spectrometry (ESI-TOF/MS) has been developed for the characterization and quantification of solanesol in extracts of tobacco leaves from different sources. The solanesol was extracted from tobacco leaf via saponification and ultrasonic-assist extraction, and the extraction conditions were optimized. The HPLC conditions are as following: Hypersil C(4) (4.6 mm x 150 mm, 5 microm) column, acetonitrile and water as mobile phase, flow-rate is 0.8 ml/min, detection length of UV is 202 nm, injection volume is 10 microl. The results indicated that the developed HPLC method is simple, sensitive and reliable for the determination of solanesol in tobacco leaves with a linear dynamic range of 3.65-4672 ng, a detection limit of 1.83 ng, and an average recovery of 98.7%. The method has been applied to analyze and compare different tobacco samples. The results show that the solanesol content in samples of different geographic locations varies widely from 0.20 to 1.50%. When different parts of the tobacco plant are compared, the top parts of the leaves are more abundant in solanesol content than those of lower parts. PMID:17029669

Chen, Junhui; Liu, Xianping; Xu, Xiaoqin; Lee, Frank Sen-Chun; Wang, Xiaoru

2006-10-06

284

UPLC Q-TOF/MS-Based Metabolic Profiling of Urine Reveals the Novel Antipyretic Mechanisms of Qingkailing Injection in a Rat Model of Yeast-Induced Pyrexia  

PubMed Central

Fever is one of the most common clinical symptoms of many diseases. Qingkailing (QKL) injection is widely used in China as a clinical emergency medicine due to its good antipyretic effects. It is a herbal formula which is composed by eight kinds of traditional Chinese medicines (TCM). As a kind of typical multiple constituents and multiple actions of TCM, it is very difficult to elaborate the antipyretic mechanism by conventional pharmacological method. Metabonomics technique provides beneficial tool for this challenge. In this study, an ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC Q-TOF/MS) metabonomics method was developed to explore the changing process of biochemical substances in rats of yeast-induced pyrexia. Partial least squares discriminate analysis (PLS-DA) was used to distinguish the normal control group, the pyrexia model group, and the pyrexia model group treated by QKL injection. The potential biomarkers related to pyrexia were confirmed and identified. MetPA was used to find the possible metabolic pathways. The results indicated that the antipyretic effect of QKL injection on yeast-induced pyrexia rats was performed by repairing the perturbed metabolism of amino acids.

Gao, Xiaoyan; Guo, Mingxing; Peng, Long; Zhao, Baosheng; Su, Jiankun; Liu, Haiyu; Zhang, Li; Bai, Xu; Qiao, Yanjiang

2013-01-01

285

Isolation and identification of flavour peptides from Puffer fish (Takifugu obscurus) muscle using an electronic tongue and MALDI-TOF/TOF MS/MS.  

PubMed

To clarify the key flavour peptides that account for the cooked taste of puffer fish, this study was performed to examine flavour peptides extracted from the flesh of puffer fish (Takifugu obscurus). Peptides fractions (P1, P2, P3, P4 and P5) were purified from an aqueous extract of T. obscurus muscle by ultrafiltration and Sephadex G-15 gel filtration chromatography (GFC). P2 was further fractionated into P2a, P2b, and P2c by reverse phase high performance liquid chromatography (RP-HPLC). Fraction P2b elicited umami and sweet taste. The amino acid sequence of P2b subfraction was identified as Tyr-Gly-Gly-Thr-Pro-Pro-Phe-Val (836.4Da) by matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF/TOF MS/MS). Hydrophilic amino acids residues Tyr, Gly, Gly, Thr, and Phe are likely to contribute to the umami and sweet taste of this octapeptide. The results of this study suggest this peptide is one of important components of the 'mellowness' and 'tenderness' taste of the T. obscurus. PMID:22953881

Zhang, Mei-Xiu; Wang, Xi-Chang; Liu, Yuan; Xu, Xing-Lian; Zhou, Guang-Hong

2012-06-26

286

Characterization of cupric glutamate extinguishing mechanism of Alexandrium sp. LC3 with two-dimensional electrophoresis and MALDI-TOF MS.  

PubMed

Mechanisms by which cupric glutamate, a novel algicide, extinguishes Alexandrium sp. LC3 are shown in this study. We show that cupric glutamate not only stimulated the production of malonaldehyde (MDA) and dramatically promoted cell plasma membrane permeability (p < 0.01) but also remarkably reduced sulfhydryl (SH) group content (p < 0.01). Analysis of protein expression profiles by two-dimensional electrophoresis (2-DE) indicated that only 47 protein spots were detected in both control and cupric glutamate treated cells. Three reliable spots were identified by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) as ribulose-bisphosphate carboxylase large subunit precursor, RNA polymerase beta chain, and hypothetical protein, which can be well correlated with cupric glutamate stress. Based on above results, we hypothesize that the extinguishing mechanisms include (1) the cell membrane being damaged by cupric glutamate; (2) cupric glutamate probably induced denaturation and disintegration of intracellular protein, which led to inhibition of cell growth. PMID:18449603

Li, Hao; Miao, Jinlai; Cui, Fengxia; Li, Guangyou

2008-05-01

287

A combined XAFS, ESI TOF-MS and LIBD study on the formation of polynuclear Zr(IV), Th(IV) and Pu(IV) species  

NASA Astrophysics Data System (ADS)

The long term radiotoxicity of spent nuclear fuel disposed of in deep underground repositories after discharge from nuclear power reactors is determined by actinide elements, mainly plutonium. Water intrusion into the repository might cause container corrosion and leaching of the waste matrices, leading to the release of Pu and other actinides into the geological environment. Performance assessment for a future nuclear waste repository requires detailed knowledge on actinide aqueous chemistry in the aquifer surrounding the disposal site. Tetravalent actinides exhibit a strong tendency towards hydrolysis and subsequent polymerization and/or colloid formation. These species provide a potential pathway for migration of actinides away from the repository. Therefore, it is of fundamental interest to study their generation and properties in-situ. To this end, X-ray Absorption Fine Structure Spectroscopy (XAFS) at the INE-Beamline for actinide research at ANKA, Electrospray Mass-Spectrometry (ESI TOF-MS) and Laser Induced Breakdown Detection (LIBD) are combined at FZK-INE in a comprehensive attempt to characterize Zr(IV) (An(IV) analogue), Th(IV) and Pu(IV) polymerization and colloid formation.

Rothe, J.; Walther, C.; Brendebach, B.; Büchner, S.; Fuss, M.; Denecke, M. A.; Geckeis, H.

2009-11-01

288

Discovery of safety biomarkers for realgar in rat urine using UFLC-IT-TOF/MS and 1H NMR based metabolomics.  

PubMed

As an arsenical, realgar (As4S4) is known as a poison and paradoxically as a therapeutic agent. However, a complete understanding of the precise biochemical alterations accompanying the toxicity and therapy effects of realgar is lacking. Using a combined ultrafast liquid chromatography (UFLC) coupled with ion trap time-of-flight mass spectrometry (IT-TOF/MS) and (1)H NMR spectroscopy based metabolomics approach, we were able to delineate significantly altered metabolites in the urine samples of realgar-treated rats. The platform stability of the liquid chromatography LC/MS and NMR techniques was systematically investigated, and the data processing method was carefully optimized. Our results indicate significant perturbations in amino acid metabolism, citric acid cycle, choline metabolism, and porphyrin metabolism. Thirty-six metabolites were proposed as potential safety biomarkers related to disturbances caused by realgar, and glycine and serine are expected to serve as the central contacts in the metabolic pathways related to realgar-induced disturbance. The LC/MS and NMR based metabolomics approach established provided a systematic and holistic view of the biochemical effects of realgar on rats, and might be employed to investigate other drugs or xenobiotics in the future. PMID:23479124

Huang, Yin; Tian, Yuan; Li, Geng; Li, Yuanyuan; Yin, Xinjuan; Peng, Can; Xu, Fengguo; Zhang, Zunjian

2013-03-13

289

Liquid chromatography - tandem quadrupole mass spectrometry and comprehensive two-dimensional gas chromatography - time-of-flight mass spectrometry measurement of targeted metabolites of Methylobacterium extorquens AM1 grown on two different carbon sources  

PubMed Central

Complementary methods using liquid chromatography - tandem quadrupole mass spectrometry (LC-MS/MS) and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF-MS) were developed and applied to determine targeted metabolites involved in central carbon metabolism [including tricarboxylic acid cycle, serine cycle, ethylmalonyl-coenzyme A (ethylmalonyl-CoA) pathway and poly-?-hydroxybutyrate cycle] of the bacterium Methylobacterium extorquens AM1 grown on two carbon sources, ethylamine (C2) and succinate (C4). Nucleotides, acyl-CoAs and a few volatile metabolites in cell extracts of M. extorquens AM1 were readily separated using either hydrophilic interaction liquid chromatography or reversed-phase liquid chromatography, and detected with good sensitivity by MS/MS. However, volatile intermediates within a low mass range (<300 m/z), especially at low abundance (such as glyoxylic acid and others <500 nM), were more effectively analyzed by GC × GC-TOF-MS which often provided better sensitivity, resolution and reproducibility. The complementary nature of the LC-based and GC-based methods allowed the comparison of 39 metabolite concentrations (the lowest level was at 139.3 nM). The overlap between the LC and GC-based methods of 7 metabolites provided a basis to check for consistency between the two methods, and thus provided some validation of the quantification accuracy. The abundance change of 20 intermediates further suggested differences in pathways linked to C2 and C4 metabolism.

Yang, Song; Sadilek, Martin; Synovec, Robert E.; Lidstrom, Mary E.

2009-01-01

290

In situ identification of plant-invasive bacteria with MALDI-TOF mass spectrometry.  

PubMed

Rhizobia form a disparate collection of soil bacteria capable of reducing atmospheric nitrogen in symbiosis with legumes. The study of rhizobial populations in nature involves the collection of large numbers of nodules found on roots or stems of legumes, and the subsequent typing of nodule bacteria. To avoid the time-consuming steps of isolating and cultivating nodule bacteria prior to genotyping, a protocol of strain identification based on the comparison of MALDI-TOF MS spectra was established. In this procedure, plant nodules were considered as natural bioreactors that amplify clonal populations of nitrogen-fixing bacteroids. Following a simple isolation procedure, bacteroids were fingerprinted by analysing biomarker cellular proteins of 3 to 13 kDa using Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry. In total, bacteroids of more than 1,200 nodules collected from roots of three legumes of the Phaseoleae tribe (cowpea, soybean or siratro) were examined. Plants were inoculated with pure cultures of a slow-growing Bradyrhizobium japonicum strain G49, or either of two closely related and fast-growing Sinorhizobium fredii strains NGR234 and USDA257, or with mixed inoculants. In the fully automatic mode, correct identification of bacteroids was obtained for >97% of the nodules, and reached 100% with a minimal manual input in processing of spectra. These results showed that MALDI-TOF MS is a powerful tool for the identification of intracellular bacteria taken directly from plant tissues. PMID:22615938

Ziegler, Dominik; Mariotti, Anna; Pflüger, Valentin; Saad, Maged; Vogel, Guido; Tonolla, Mauro; Perret, Xavier

2012-05-17

291

In Situ Identification of Plant-Invasive Bacteria with MALDI-TOF Mass Spectrometry  

PubMed Central

Rhizobia form a disparate collection of soil bacteria capable of reducing atmospheric nitrogen in symbiosis with legumes. The study of rhizobial populations in nature involves the collection of large numbers of nodules found on roots or stems of legumes, and the subsequent typing of nodule bacteria. To avoid the time-consuming steps of isolating and cultivating nodule bacteria prior to genotyping, a protocol of strain identification based on the comparison of MALDI-TOF MS spectra was established. In this procedure, plant nodules were considered as natural bioreactors that amplify clonal populations of nitrogen-fixing bacteroids. Following a simple isolation procedure, bacteroids were fingerprinted by analysing biomarker cellular proteins of 3 to 13 kDa using Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry. In total, bacteroids of more than 1,200 nodules collected from roots of three legumes of the Phaseoleae tribe (cowpea, soybean or siratro) were examined. Plants were inoculated with pure cultures of a slow-growing Bradyrhizobium japonicum strain G49, or either of two closely related and fast-growing Sinorhizobium fredii strains NGR234 and USDA257, or with mixed inoculants. In the fully automatic mode, correct identification of bacteroids was obtained for >97% of the nodules, and reached 100% with a minimal manual input in processing of spectra. These results showed that MALDI-TOF MS is a powerful tool for the identification of intracellular bacteria taken directly from plant tissues.

Pfluger, Valentin; Saad, Maged; Vogel, Guido; Tonolla, Mauro; Perret, Xavier

2012-01-01

292

Metabolic fingerprinting using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.  

PubMed

Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF-MS) is applied to the comparative metabolic fingerprinting of physiological fluids. Stable isotope-labeled internal standards plus norvaline serve as extraction standards and are added to the blanks, controls and patient samples prior to protein precipitation with methanol. The extracts are evaporated to complete dryness and derivatized in two steps using methoximation with methoxylamine hydrochloride (MeOx) and silylation with N-methyl-N-trimethylsily-trifluoroacetamide (MSTFA). Between derivatization steps a second internal standard containing odd-numbered, saturated straight chain fatty acids is added for quality control and to normalize retention time shifts. After GC × GC-TOF-MS analysis raw data are processed, aligned, and combined in one data matrix for subsequent statistical evaluation. Both a custom-made and the NIST 05 library are used to preliminarily identify significant metabolites. For verification purposes, commercial standards are run individually. Absolute quantification of selected metabolites is achieved by using a multi-point calibration curve and isotope-labeled internal standards. PMID:22131007

Almstetter, Martin F; Oefner, Peter J; Dettmer, Katja

2012-01-01

293

Use of matrix-assisted laser desorption ionization-time of flight mass spectrometry to identify vancomycin-resistant enterococci and investigate the epidemiology of an outbreak.  

PubMed

The control of vancomycin-resistant enterococci (VRE) has become an increasing burden on health care resources since their discovery over 20 years ago. Current techniques employed for their detection include time-consuming and laborious phenotypic methods or molecular methods requiring costly equipment and consumables and highly trained staff. An accurate, rapid diagnostic test has the ability to greatly reduce the spread of this organism, which has the ability to colonize patients for long periods, potentially even lifelong. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a technology with the ability to identify organisms in seconds and has shown promise in the identification of other forms of antimicrobial resistance in other organisms. Here we show that MALDI-TOF MS is capable of rapidly and accurately identifying vanB-positive Enterococcus faecium VRE from susceptible isolates. Internal validation of the optimal model generated produced a sensitivity of 92.4% and a specificity of 85.2%. Prospective validation results, following incorporation into the routine laboratory work flow, demonstrated a greater sensitivity and specificity at 96.7% and 98.1%, respectively. In addition, the utilization of MALDI-TOF MS to determine the relatedness of isolates contributing to an outbreak is also demonstrated. PMID:22740710

Griffin, Paul M; Price, Gareth R; Schooneveldt, Jacqueline M; Schlebusch, Sanmarié; Tilse, Martyn H; Urbanski, Tess; Hamilton, Brett; Venter, Deon

2012-06-27

294

Screening for in vitro metabolites of Abelmoschus manihot extract in intestinal bacteria by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.  

PubMed

Abelmoschus manihot has drawn much attention recently due to its potential beneficial health effects after oral administration. However, the metabolic fate of A. manihot in intestinal flora is not well understood. In this paper, we describe a strategy using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS) with automated data analysis software (MetaboLynx™) for fast analysis of the metabolic profile of flavonoids from A. manihot in intestinal flora. The human and rat incubated samples collected 72 h in the anaerobic incubator were analyzed by UPLC-Q-TOF MS within 10 min. A total of 14 metabolites were identified in human and rat incubated solution compared with blank samples. The results indicated that hydrolysis, hydroxylation and acetylation were the major metabolic pathways of flavonoids in A. manihot extract in vitro. MS(E) was used for simultaneous acquisition of precursor ion information and fragment ion data at high and low collision energy in one analytical run, which facilitated the fast structural characterization of metabolites. This work demonstrated the potential of the UPLC-Q-TOF MS approach using Metabolynx for fast and automated identification of metabolites of natural product in intestinal flora. PMID:22119023

Xue, Caifu; Jiang, Shu; Guo, Jianming; Qian, Dawei; Duan, Jin-ao; Shang, Erxin

2011-11-07

295

Identification of Mycobacteria in Solid-Culture Media by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry?  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has recently been introduced into the clinical microbiology laboratory as a rapid and accurate method to identify bacteria and yeasts. In this paper we describe our work on the use of MALDI-TOF MS for the identification of mycobacterial isolates. We developed a protocol for protein extraction from mycobacteria and utilized it to construct a database containing 42 clinically relevant type and reference strains of mycobacteria. The database was used to identify 104 clinical isolates of mycobacteria. All members of the Mycobacterium tuberculosis complex were identified accurately at the complex level but could not be separated at the species level. All other organisms were identified at the species level, with the exception of one strain of M. kansasii (accurately identified but with a low spectral score) and three pairs of closely related strains: M. abscessus and M. massiliense, M. mucogenicum and M. phocaicum, and M. chimaera and M. intracellulare. These pairs of organisms can currently be identified only by multilocus gene sequence analysis. We conclude that MALDI-TOF MS analysis can be incorporated into the work flow of the microbiology laboratory for rapid and accurate identification of most strains of mycobacteria isolated from solid growth media.

Saleeb, Paul G.; Drake, Steven K.; Murray, Patrick R.; Zelazny, Adrian M.

2011-01-01

296

Novel Approach for Differentiating Shigella Species and Escherichia coli by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.  

PubMed

Shigella species are so closely related to Escherichia coli that routine matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) cannot reliably differentiate them. Biochemical and serological methods are typically used to distinguish these species; however, "inactive" isolates of E. coli are biochemically very similar to Shigella species and thus pose a greater diagnostic challenge. We used ClinProTools (Bruker Daltonics) software to discover MALDI-TOF MS biomarker peaks and to generate classification models based on the genetic algorithm to differentiate between Shigella species and E. coli. Sixty-six Shigella spp. and 72 E. coli isolates were used to generate and test classification models, and the optimal models contained 15 biomarker peaks for genus-level classification and 12 peaks for species-level classification. We were able to identify 90% of E. coli and Shigella clinical isolates correctly to the species level. Only 3% of tested isolates were misidentified. This novel MALDI-TOF MS approach allows laboratories to streamline the identification of E. coli and Shigella species. PMID:23985919

Khot, Prasanna D; Fisher, Mark A

2013-08-28

297

High-resolution human papillomavirus genotyping by MALDI-TOF mass spectrometry.  

PubMed

We describe a matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS)-based assay for human papillomavirus (HPV) genotyping--the restriction fragment mass polymorphism (RFMP) assay, which is based on mass measurement of genotype-specific oligonucleotide fragments generated by TypeIIS restriction endonuclease cleavage after recognition sites have been introduced by PCR amplification. The use of a TypeIIS restriction enzyme makes the RFMP assay independent of sequence and applicable to a wide variety of HPV genotypes, because these enzymes have cleavage sites at a fixed distance from their recognition sites. After PCR amplification, samples are subjected to restriction enzyme digestion with FokI and BtsCI and desalting using Oasis purification plates, followed by analysis by MALDI-TOF MS. Overall, the protocol is simple, takes approximately 4-4.5 h and can accurately detect and identify at least 74 different HPV genotypes. PMID:18772875

Hong, Sun Pyo; Shin, Soo-Kyung; Lee, Eun Hee; Kim, Eun Ok; Ji, Seung Il; Chung, Hyun Jae; Park, Sun Nie; Yoo, Wangdon; Folk, William R; Kim, Soo-Ok

2008-01-01

298

Direct Laser Ablation and Ionization of Solids for Chemical Analysis by Mass Spectrometry  

SciTech Connect

A laser ablation/ionization mass spectrometer system is described for the direct chemical analysis of solids. An Nd:YAG laser is used for ablation and ionization of the sample in a quadrupole ion trap operated in an ion-storage (IS) mode that is coupled with a reflectron time-of-flight mass spectrometer (TOF-MS). Single pulse experiments have demonstrated simultaneous detection of up to 14 elements present in glasses in the ppm range. However, detection of the components has produced non-stoichiometric results due to difference in ionization potentials and fractionation effects. Time-of-flight secondary ionization mass spectrometry (TOF-SIMS) was used to spatially map elemental species on the surface and provide further evidence of fractionation effects. Resolution (m/Dm) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.

Holt, J K; Nelson, E J; Klunder, G L

2005-09-02

299

Direct bacterial identification in positive blood cultures by use of two commercial matrix-assisted laser desorption ionization-time of flight mass spectrometry systems.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria and fungi was recently introduced in microbiology laboratories. This technology could greatly improve the clinical management of patients and guidance for chemotherapy. In this study, we used a commercial MALDI Sepsityper extraction method to evaluate the performance of two commercial MALDI-TOF MS systems, the Vitek MS IVD (bioMérieux) and the Microflex LT Biotyper (Bruker Daltonics) for direct bacterial identification in positive blood cultures. In 181 monomicrobial cultures, both systems generated genus to species level identifications for >90% of the specimens (Biotyper, 177/181 [97.8%]; Vitek MS IVD, 167/181 [92.3%]). Overall, the Biotyper system generated significantly more accurate identifications than the Vitek MS IVD system (P = 0.016; 177 versus 167 out of 181 specimens). The Biotyper system identified the minority species among polymicrobial blood cultures. We also compared the performance of an in-house extraction method with that of the Sepsityper on both MALDI-TOF MS systems. The in-house method generated more correct identifications at the genus level than the Sepsityper (96.7% versus 93.5%) on the Biotyper system, whereas the two methods exhibited the same performance level (88.0% versus 88.0%) on the Vitek MS IVD system. Our study confirmed the practical advantages of MALDI-TOF MS, and our in-house extraction method reduced the reagent cost to $1 per specimen, with a shorter turnaround time of 3 h, which is highly cost-effective for a diagnostic microbiology service. PMID:23515548

Chen, Jonathan H K; Ho, Pak-Leung; Kwan, Grace S W; She, Kevin K K; Siu, Gilman K H; Cheng, Vincent C C; Yuen, Kwok-Yung; Yam, Wing-Cheong

2013-03-20

300

Oral brush biopsy analysis by matrix assisted laser desorption/ionisation-time of flight mass spectrometry profiling--a pilot study.  

PubMed

Oral squamous cell carcinomas (OSCCs) often present as advanced tumours requiring aggressive local and regional therapy and result in significant functional impairment. The objective is to develop pre-symptomatic screening detection of OSCC by a brush biopsy method which is less invasive than the conventional biopsy for histology. Given the molecular heterogeneity of oral cancer, it is unlikely that even a panel of tumour markers would provide accurate diagnosis. Therefore, approaches such as the matrix-assisted-laser-desorption/ionisation-time-of-flight-mass-spectrometry (MALDI-TOF-MS) allow several biomarkers or peptide profile patterns to be simultaneously assessed. Brush biopsies from 27 patients with histology-proven OSCCs plus 40 biopsies from 10 healthy controls were collected. MALDI-TOF-MS profiling was performed and additional statistical analysis of the data was used to classify the disease status according to the biological behaviour of the lesion. For classification a support vector machine algorithm was trained using spectra of brush biopsy samples to distinguish healthy control patients from patients with histology-proven OSCC. MALDI-TOF-MS was able to distinguish between healthy patients and OSCC patients with a sensitivity of 100% and specificity of 93%. In summary, MALDI-TOF-MS in combination with sophisticated bioinformatic methods can distinguish OSCC patients from non-cancer controls with excellent sensitivity and specificity. Further improvement and validation of this approach is necessary to determine its feasibility to assist the pre-symptomatic detection of head and neck cancer screening in routine daily practice. PMID:21354855

Remmerbach, Torsten W; Maurer, Katja; Janke, Sebastian; Schellenberger, Wolfgang; Eschrich, Klaus; Bertolini, Julia; Hofmann, Herbert; Rupf, Stefan

2011-02-26

301

Screening and characterization of natural antioxidants in four Glycyrrhiza species by liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.  

PubMed

Licorice, derived from the dried roots and rhizomes of several species of genus Glycyrrhiza L. (Leguminosae family), has been traditionally used in herbal medicine for over 4000 years. In recent years, the interest in antioxidative constituents in licorice has greatly increased. In this work, a new method based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) spiking test combined with HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) analysis was developed to screen and identify the antioxidants in licorice. The results of the method validation indicated that the developed method was reliable and repeatable. Compared with DPPH on-line method, the HPLC-Q-TOF MS/MS method combined with DPPH spiking test offered much higher sensitivity and resolution. Using this method, 35 radical scavengers were screened from four Glycyrrhiza species (G. inflata, G. glabra, G. pallidiflora and G. uralensis), and 21 of them were unambiguously or tentatively identified by HPLC-Q-TOF MS/MS. Among the 21 identified flavonoids, 10 compounds had been reported to possess antioxidative activities in the previous studies, and the radical scavenging activities of the other 11 compounds were reported for the first time. The effects of six purified flavonoids on DPPH radical and lipid peroxidation were evaluated for validation of the developed method. The results indicated that HPLC-Q-TOF MS/MS coupled with DPPH treatment is an efficient and powerful method to discover the potential antioxidative compounds from the complex natural product mixtures. In this study, the identified components with free radical scavenging activity, would help to explain the therapeutic benefit of licorice in the treatment of human disease associated with oxidative stress. PMID:21968349

Li, Yan-Jing; Chen, Jun; Li, Ying; Li, Qin; Zheng, Yun-Feng; Fu, Yu; Li, Ping

2011-09-16

302

Conceptual Study on New Isotope Analysis Technique with Resonance Ionization Mass Spectrometry Using Inductively Coupled Plasma as an Atomic Source (ICP-RIMS)  

SciTech Connect

We have proposed the novel isotope analysis technique with Resonance Ionization Mass Spectrometry using Inductively Coupled Plasma as an atomic source (ICP-RIMS). Each component of ICP-RIMS is conceptually designed. We conclude that the orthogonal acceleration time-of-flight mass spectrometer (oa-TOF-MS) driven by a high-repetition-rate pulsed laser would be suitable system for ICP-RIMS. We, additionally, suggest that the first vacuum stage of the vacuum interface, which is between the sampling and skimmer cones, is desired to maintain as low pressure as possible in order to suppress the Doppler broadening and to skim the supersonic jet effectively.

Watanabe, K.; Uritani, A. [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Higuchi, Y.; Tomita, H.; Kawarabayashi, J.; Iguchi, T. [Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

2009-03-17

303

Chaperonin GroEL a Brucella immunodominant antigen identified using Nanobody and MALDI-TOF-MS technologies.  

PubMed

The deployment of today's antibodies that are able to distinguish Brucella from the closely similar pathogens, such as Yersinia, is still considered a great challenge since both pathogens share identical LPS (lipopolysaccharide) O-ring epitopes. In addition, because of the great impact of Brucella on health and economy in many countries including Syria, much effort is going to the development of next generation vaccines, mainly on the identification of new immunogenic proteins of this pathogen. In this context, Brucella-specific nanobodies (Nbs), camel genetic engineered heavy-chain antibody fragments, could be of great value. Previously, a large Nb library was constructed from a camel immunized with heat-killed Brucella. Phage display panning of this 'immune' library with Brucella total lysate resulted in a remarkable fast enrichment for a Nb referred to as NbBruc02. In the present work, we investigated the main characteristics of this Nb that can efficiently distinguish under well-defined conditions the Brucella from other bacteria including Yersinia. NbBruc02 showed a strong and specific interaction with its antigen within the crude lysate as tested by a surface plasmon resonance (SPR) biosensor and it was also able to pull down its cognate antigen from such lysate by immuno-capturing. Using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), NbBruc02 specific antigen was identified as chaperonin GroEL, also known as heat shock protein of 60 kDa (HSP-60), which represents a Brucella immunodominant antigen responsible of maintaining proteins folding during stress conditions. Interestingly, the antigen recognition by NbBruc02 was found to be affected by the state of GroEL folding. Thus, the Nb technology applied in the field of infectious diseases, e.g. brucellosis, yields two outcomes: (1) it generates specific binders that can be used for diagnosis, and perhaps treatment, and (2) it identifies the immunogenic candidate antigens for developing vaccines. PMID:22472910

Abbady, A Q; Al-Daoude, A; Al-Mariri, A; Zarkawi, M; Muyldermans, S

2012-03-03

304

UPLC-Q-TOF/MS coupled with multivariate statistical analysis as a powerful technique for rapidly exploring potential chemical markers to differentiate between radix paeoniae alba and radix paeoniae rubra.  

PubMed

To explore rapidly the potential chemical markers for differentiating Radix Paeoniae Alba and Radix Paeoniae Rubra, a method is proposed based on ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) coupled with multivariate statistical analysis. Batches of commercial samples were analyzed by UPLC-Q-TOF/MS. The datasets of t(R)-m/z pair, ion intensities and sample codes were further processed with orthogonal partial least squared discriminant analysis (OPLS-DA) to compare holistically the difference between these two kinds of samples. Then statistics were used to generate an S-plot, in which the variables (t(R)-m/z pair) contributing most to the difference were clearly depicted as points at the two ends of "S", and the components correlated to these ions should be regarded as the chemical markers. The identities of the most changed markers can be identified by comparing the mass/UV spectra and retention times with those of reference compounds and/or tentatively assigned by matching empirical molecular formulae with those of known compounds published in the literature. Using this proposed approach, albflorin, paeoniflorin, oxypaeoniflorin, benzoylpaeoniflorin, galloylalbiflorin and paeoniflorigenone were found to be the differentiating components for discrimination of Radix Paeoniae Alba and Radix Paeoniae Rubra. Moreover, paeoniflorin sulfonate and its isomer, isomaltopaeoniflorin sulfonate, were found to be the characteristic markers for all Radix Paeoniae Alba samples that were processed by sulfurdioxide gas fumigation. The results suggested that this newly established approach could be used to explore rapidly the potential chemical markers for herbs with similar chemical characteristics. PMID:23738461

Luo, Nian-Cui; Ding, Wen; Wu, Jing; Qian, Da-Wei; Li, Zhen-Hao; Qian, Ye-Fei; Guo, Jian-Ming; Duan, Jin-Ao

2013-04-01

305

Mass spectrometry and proteomics  

Microsoft Academic Search

Proteomics is the systematic analysis of the proteins expressed by a cell or tissue, and mass spectrometry is its essential analytical tool. In the past two years, incremental advances in standard proteome technology have increased the speed of protein identification with higher levels of automation and sensitivity. Furthermore, new approaches have provided landmark advances in determining functionally relevant properties of

Steven P Gygi; Ruedi Aebersold; J YATESIII

2000-01-01

306

Analytical mass spectrometry  

SciTech Connect

This 43rd Annual Summer Symposium on Analytical Chemistry was held July 24--27, 1990 at Oak Ridge, TN and contained sessions on the following topics: Fundamentals of Analytical Mass Spectrometry (MS), MS in the National Laboratories, Lasers and Fourier Transform Methods, Future of MS, New Ionization and LC/MS Methods, and an extra session. (WET)

Not Available

1990-01-01

307

Analytical mass spectrometry. Abstracts  

SciTech Connect

This 43rd Annual Summer Symposium on Analytical Chemistry was held July 24--27, 1990 at Oak Ridge, TN and contained sessions on the following topics: Fundamentals of Analytical Mass Spectrometry (MS), MS in the National Laboratories, Lasers and Fourier Transform Methods, Future of MS, New Ionization and LC/MS Methods, and an extra session. (WET)

Not Available

1990-12-31

308

Improving peptide relative quantification in MALDI-TOF MS for biomarker assessment.  

PubMed

Proteomic profiling by MALDI-TOF MS presents various advantages (speed of analysis, ease of use, relatively low cost, sensitivity, tolerance against detergents and contaminants, and possibility of automation) and is being currently used in many applications (e.g. peptide/protein identification and quantification, biomarker discovery, and imaging MS). Earlier studies by many groups indicated that moderate reproducibility in relative peptide quantification is a major limitation of MALDI-TOF MS. In the present work, we examined and demonstrate a clear effect, in cases apparently random, of sample dilution in complex samples (urine) on the relative quantification of peptides by MALDI-TOF MS. Results indicate that in urine relative abundance of peptides cannot be assessed with confidence based on a single MALDI-TOF MS spectrum. To account for this issue, we developed and propose a novel method of determining the relative abundance of peptides, taking into account that peptides have individual linear quantification ranges in relation to sample dilution. We developed an algorithm that calculates the range of dilutions at which each peptide responds in a linear manner and normalizes the received peptide intensity values accordingly. This concept was successfully applied to a set of urine samples from patients diagnosed with diabetes presenting normoalbuminuria (controls) and macroalbuminuria (cases). PMID:23943474

Albalat, Amaya; Stalmach, Angelique; Bitsika, Vasiliki; Siwy, Justyna; Schanstra, Joost P; Petropoulos, Alexandros D; Vlahou, Antonia; Jankowski, Joachim; Persson, Frederik; Rossing, Peter; Jaskolla, Thorsten W; Mischak, Harald; Husi, Holger

2013-10-01

309

Ellagitannin Composition of Blackberry As Determined by HPLC-ESI-MS and MALDI-TOF-MS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Apache blackberries (Rubus sp.) were evaluated by HPLC-MS and MALDI-TOF-MS to identify ellagitannins present in the flesh, torus (receptacle tissue), and seeds. Most ellagitannins were only present or detectable in seed tissues. Ellagitannins identified by HPLC-MS in the seeds included pedunculagi...

310

Dihydrobenzoic acid modified nanoparticle as a MALDI-TOF MS matrix for soft ionization and structure determination of small molecules with diverse structures.  

PubMed

Efficient structural characterization is important for quality control when developing novel materials. In this study, we demonstrated the soft ionization capability of the hybrid of immobilized silica and 2,5-dihydrobenzoic acid (DHB) on iron oxide magnetic nanoparticles in MALDI-TOF MS with a clean background. The ratio between SiO(2) and DHB was examined and was found to affect the surface immobilization of DHB on the nanoparticle, critically controlling the ionization efficiency and interference background. Compared with commercial DHB, the functionalized nanoparticle-assisted MALDI-TOF MS provided superior soft ionization with production of strong molecular ions within 5 ppm mass accuracy on a variety of new types of synthetic materials used for solar cells, light emitting devices, dendrimers, and glycolipids, including analytes with either thermally labile structures or poor protonation tendencies. In addition, the enhancements of the molecular ion signal also provided high-quality product-ion spectra allowing structural characterization and unambiguous small molecule identification. Using this technique, the structural differences among the isomers were distinguished through their characteristic fragment ions and comprehensive fragmentation patterns. With the advantages of long-term stability and simple sample preparation by deposition on a regular sample plate, the use of DHB-functionalized nanoparticles combined with high-resolution MALDI-TOF MS provides a generic platform for rapid and unambiguous structure determination of small molecules. PMID:20739189

Tseng, Mei-Chun; Obena, Rofeamor; Lu, Ying-Wei; Lin, Po-Chiao; Lin, Ping-Yu; Yen, Yung-Sheng; Lin, Jiann-Tsuen; Huang, Li-De; Lu, Kuang-Lieh; Lai, Long-Li; Lin, Chun-Cheng; Chen, Yu-Ju

2010-08-05

311

Determination of distinctive carbohydrate signatures obtained from the Aeromonas hydrophila (chemotype II) core oligosaccharide pinpointing the presence of the 4-O-phosphorylated 5-O-linked Kdo reducing end group using electrospray ionization quadrupole orthogonal time-of-flight mass spectrometry and tandem mass spectrometry.  

PubMed

The electrospray quadrupole orthogonal time-of-flight mass spectrometric (ESI-QqTOF-MS) structural elucidation of the core oligosaccharide of Aeromonas hydrophila (chemotype II) lipopolysaccharide has been investigated and it was demonstrated that it contained an 4-O-phosphorylated Kdo reducing end group, which was glycosylated by the remaining outer core oligosaccharide through its O-5 position. After releasing the core oligosaccharide from the native LPS with acid, the phosphorylated Kdo residue eliminated phosphoric acid, to produce a core oligosaccharide containing a mixture of diastereomeric 4,8- and 4,7-anhydro-alpha-keto acids and an open-chain olefinic Kdo residue. The characteristic glycone sequence was elucidated by collision-induced dissociation tandem mass spectrometry (CID-MS/MS) of the protonated molecule of the native core oligosaccharide. In addition, the analysis of the Hakomori permethylated core oligosaccharide was carried out by electrospray ionization quadrupole orthogonal time-of-flight mass spectrometry (ESI-QqTOF-MS) and matrix-assisted laser desorption/ionization (MALDI)-QqTOF-MS analyses. The presence of more than nine isobaric isomers of this core was detected. The CID-MS/MS analysis of the various protonated permethylated core oligosaccharide molecules showed a similar and diagnostic fragmentation pattern. The over-methylation of the permethylated core oligosaccharide containing either the 4,7- or the 4,8-anhydro-alpha-keto acid unit and the open-chain olefinic Kdo unit was reported. It was realized that the extra minor satellite signals obtained in the ESI-QqTOF-MS and MALDI-TOF-MS analyses were dimethyl sulfoxide (DMSO) stable covalent addition products, which have occurred by a Michael addition on the 4,8-Kdo exocyclic double bond. The occurrence of this series of covalent addition products during the MS analysis of a permethylated core oligosaccharide should be considered as 'carbohydrate-distinctive signatures' establishing and confirming the presence of a 4-O-phosphorylated-5-O-linked Kdo reducing end group. PMID:20740521

Sioud, Salim; Jahouh, Farid; Nashed, Mina; Joly, Nicolas; Banoub, Joseph H

2010-09-15

312

SELDI-TOF-MS ProteinChip array profiling of T-cell clones propagated in long-term culture identifies human profilin-1 as a potential bio-marker of immunosenescence  

PubMed Central

Background The adaptive immune response requires waves of T-cell clonal expansion on contact with pathogen and elimination after clearance of the source of antigen. However, lifelong persistent infections with common viruses cause chronic antigenic stimulation which takes its toll on adaptive immunity in late life. Chronic antigenic stress results in deregulation of the T-cell response and accumulation of anergic cells. Longitudinal studies of the elderly show that this impacts on survival. Identifying the nature of the defects in chronically-stimulated T-cells and protein bio-markers of these dysfunctional cells would help to understand age-associated compromised T-cell function (immunosenescence) and facilitate the development of targeted intervention strategies. The purpose of this work was to use surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to analyse proteins associated with T-cell senescence in order to identify potential bio-markers. Clonal populations of T-cells isolated from elderly octogenarian and centenarian donors were grown in vitro until senescence, and early passage and late passage (pre-senescent) cells were analysed using SELDI-TOF-MS ProteinChip arrays. Results Discriminant analysis identified several protein or peptide peaks in the region of 14.5–16.5 kDa that were associated with T-cell clone senescence. Human profilin-1, a ubiquitous protein associated with actin remodelling and cellular motility was unambiguously identified. Altered expression of profilin-1 in senescent T-cell clones was confirmed by Western blot analysis. Conclusion Due to the proposed roles of profilin-1 in cellular survival, cytoskeleton remodelling, motility, and proliferation, it is hypothesised that differential expression of profilin-1 in ageing may contribute directly to immunosenescence.

Mazzatti, Dawn J; Pawelec, Graham; Longdin, Robin; Powell, Jonathan R; Forsey, Rosalyn J

2007-01-01

313

Mass spectrometry with accelerators.  

PubMed

As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH?2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative methods of isobar separation. These techniques are discussed in the latter part of the review. PMID:22031277

Litherland, A E; Zhao, X-L; Kieser, W E

2010-12-23

314

Analysis of recombinant monoclonal antibody isoforms by electrospray ionization mass spectrometry as a strategy for streamlining characterization of recombinant monoclonal antibody charge heterogeneity.  

PubMed

A therapeutic recombinant monoclonal antibody analyzed by cation-exchange chromatography exhibited a heterogeneous profile composed of approximately 10 isoforms. The peaks were isolated and characterized by electrospray quadrupole time-of-flight mass spectrometry (ESI-q-TOF-MS), N-terminal Edman sequencing, peptide mapping, and other techniques. Acidic (lower pI) peaks were found to represent deamidated and sialyated species. Higher pI peaks were found to contain N- and C-terminal heavy-chain variants. Biological activities of the more abundant isoforms were found to be comparable. An approach streamlining the characterization of antibody charge heterogeneity is proposed. PMID:16289440

Lyubarskaya, Yelena; Houde, Damian; Woodard, James; Murphy, David; Mhatre, Rohin

2005-10-25

315

Development of a MALDI two-layer volume sample preparation technique for analysis of colored conidia spores of Fusarium by MALDI linear TOF mass spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI–TOF MS) has been proved to be a powerful\\u000a tool for the identification and characterization of microorganisms based on their surface peptide\\/protein pattern. Because\\u000a of the complexity of microorganisms, there are no standardized protocols to acquire reproducible peptide\\/protein profiles\\u000a for a broad range of microorganisms and for fungi in particular. Small variations during MALDI

Hongjuan Dong; Jasmin Kemptner; Martina Marchetti-Deschmann; Christian Peter Kubicek; Günter Allmaier

2009-01-01

316

Molecular analysis of native tissue and whole oils by infrared laser mass spectrometry.  

PubMed

We have employed infrared laser desorption ionization orthogonal time-of-flight mass spectrometry (IR-LDI-o-TOF-MS) to generate molecular ion profiles directly from native tissue and from whole oils. The method requires little sample preparation besides an eventual dissection of the areas of interest and drying of particularly water-rich samples. The lateral resolution of the analysis is on the order of the laser focal diameter, and in the third dimension, defined by the depth of material ejection, a few to 10 microm per laser pulse. Various types of small molecules are readily detected from minute volumes of sample. Among these are carbohydrates, phospholipids, triglycerides, and flavonoids. Substantially different molecular profiles were recorded from different areas of a single strawberry seed. PMID:17500536

Dreisewerd, Klaus; Draude, Felix; Kruppe, Sarah; Rohlfing, Andreas; Berkenkamp, Stefan; Pohlentz, Gottfried

2007-05-15

317

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Nocardia Species?  

PubMed Central

The identification of Nocardia species, usually based on biochemical tests together with phenotypic in vitro susceptibility and resistance patterns, is a difficult and lengthy process owing to the slow growth and limited reactivity of these bacteria. In this study, a panel of 153 clinical and reference strains of Nocardia spp., altogether representing 19 different species, were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). As reference methods for species identification, full-length 16S rRNA gene sequencing and phenotypical biochemical and enzymatic tests were used. In a first step, a complementary homemade reference database was established by the analysis of 110 Nocardia isolates (pretreated with 30 min of boiling and extraction) in the MALDI BioTyper software according to the manufacturer's recommendations for microflex measurement (Bruker Daltonik GmbH, Leipzig, Germany), generating a dendrogram with species-specific cluster patterns. In a second step, the MALDI BioTyper database and the generated database were challenged with 43 blind-coded clinical isolates of Nocardia spp. Following addition of the homemade database in the BioTyper software, MALDI-TOF MS provided reliable identification to the species level for five species of which more than a single isolate was analyzed. Correct identification was achieved for 38 of the 43 isolates (88%), including 34 strains identified to the species level and 4 strains identified to the genus level according to the manufacturer's log score specifications. These data suggest that MALDI-TOF MS has potential for use as a rapid (<1 h) and reliable method for the identification of Nocardia species without any substantial costs for consumables.

Verroken, A.; Janssens, M.; Berhin, C.; Bogaerts, P.; Huang, T.-D.; Wauters, G.; Glupczynski, Y.

2010-01-01

318

MALDI Mass Spectrometry Imaging of Neuronal Cell Cultures  

NASA Astrophysics Data System (ADS)

Mass spectrometry imaging (MSI) provides the ability to detect and identify a broad range of analytes and their spatial distributions from a variety of sample types, including tissue sections. Here we describe an approach for probing neuropeptides from sparse cell cultures using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MSI—at single cell spatial resolution—in both MS and tandem MS modes. Cultures of Aplysia californica neurons are grown on an array of glass beads embedded in a stretchable layer of Parafilm M. As the membrane is stretched, the beads/neurons are separated physically and the separated beads/neurons analyzed via MALDI TOF MS. Compared with direct MS imaging of samples, the stretching procedure enhances analyte extraction and incorporation into the MALDI matrix, with negligible analyte spread between separated beads. MALDI tandem MSI using the stretched imaging approach yields localization maps of both parent and fragment ions from Aplysia pedal peptide, thereby confirming peptide identification. This methodology represents a flexible platform for MSI investigation of a variety of cell cultures, including functioning neuronal networks.

Zimmerman, Tyler A.; Rubakhin, Stanislav S.; Sweedler, Jonathan V.

2011-05-01

319

Potential of liquid chromatography\\/time-of-flight mass spectrometry for the determination of pesticides and transformation products in water  

Microsoft Academic Search

Until now, time-of-flight (TOF) mass analysers have only been very rarely used in pesticide residue analysis (PRA) of water\\u000a samples. However, the inherent characteristics of TOF MS make these analysers well-suited to this field, mainly for qualitative\\u000a purposes. Thus, the high sensitivity obtained from full-scan acquisition in comparison to other MS analysers and the high\\u000a resolution of TOF MS suggest

Juan V. Sancho; Óscar J. Pozo; María Ibáñez; Félix Hernández

2006-01-01

320

The Interaction Between Endopolygalacturonase From Fusarium Moniliforme and PGIP from Phaseolus Vulgaris Studied by Surface Plasmon Resonance and Mass Spectrometry  

PubMed Central

A combination of surface plasmon resonance (SPR) and matrix-assisted laser-desorptionionization- time-of-flight mass spectrometry (MALDI-TOF-MS) was used to study the interaction between endopolygalacturonase (PG) from Fusarium moniliforme and a polygalacturonase-inhibiting protein (PGIP) from Phaseolus vulgaris. PG hydrolyses the homogalacturonan of the plant cell wall and is considered an important pathogenicity factor of many fungi. PGIP is a specific inhibitor of fungal PGs and is thought to be involved in plant defence against phytopathogenic fungi. SPR was used either to study the effect of the PG glycosylation on the formation of the complex with PGIP, and as a sensitive affinity capture of an interacting peptide from a mixture of PG fragments obtained by limited proteolysis. Mass spectrometry allowed to characterise the interacting peptide eluted from the sensor surface.

Cervone, Felice; Roepstorff, Peter

2001-01-01

321

Comprehensive non-targeted analysis of contaminated groundwater of a former ammunition destruction site using 1H-NMR and HPLC-SPE-NMR/TOF-MS.  

PubMed

The aim of the present study was to explore the capabilities of the combination of 1H NMR (proton nuclear magnetic resonance) mixture analysis and HPLC-SPE-NMR/TOF-MS (high-performance liquid chromatography coupled to solid-phase extraction and nuclear magnetic resonance and time-of-flight mass spectrometry) for the characterization of xenobiotic contaminants in groundwater samples. As an example, solid-phase extracts of two groundwater samples taken from a former ammunition destruction site in Switzerland were investigated. 1H NMR spectra of postcolumn SPE enriched compounds, together with accurate mass measurements, allowed the structural elucidation of unknowns. This untargeted approach allowed us to identify expected residues of explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT), Hexogen (RDX) and Octogen (HMX), degradation products of TNT (1,3,5-trinitrobenzene (1,3,5-TNB), 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT), 3,5-dinitrophenol (3,5-DNP), 3,5-dinitroaniline (3,5-DNA), 2,6-dinitroanthranite, and 2-Hydroxy-4,6-dinitrobenzonitrile), benzoic acid, Bisphenol A (a known endocrine disruptor compound), and some toxicologically relevant additives for propelling charges: Centralite I (1,3-diethyl-1,3-diphenylurea), DPU (N,N-diphenylurethane), N,N-diphenylcarbamate (Acardite II), and N-methyl-N-phenylurethane. To our knowledge, this is the first report of the presence of these additives in environmental samples. Extraction recoveries for Centralite I and DPU have been determined. Contaminants identified by our techniques were quantified based on HPLC-UV (HPLC-ultraviolet detection) and 1H NMR mixture analysis. The concentrations of the contaminants ranged between 0.1 and 48 microg/L assuming 100% recovery for the SPE step. PMID:19806741

Godejohann, Markus; Heintz, Lea; Daolio, Cristina; Berset, Jean-Daniel; Muff, Daniel

2009-09-15

322

Identification of novel biomarker candidates by proteomic analysis of cerebrospinal fluid from patients with moyamoya disease using SELDI-TOF-MS  

PubMed Central

Background Moyamoya disease (MMD) is an uncommon cerebrovascular condition with unknown etiology characterized by slowly progressive stenosis or occlusion of the bilateral internal carotid arteries associated with an abnormal vascular network. MMD is a major cause of stroke, specifically in the younger population. Diagnosis is based on only radiological features as no other clinical data are available. The purpose of this study was to identify novel biomarker candidate proteins differentially expressed in the cerebrospinal fluid (CSF) of patients with MMD using proteomic analysis. Methods For detection of biomarkers, CSF samples were obtained from 20 patients with MMD and 12 control patients. Mass spectral data were generated by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) with an anion exchange chip in three different buffer conditions. After expression difference mapping was undertaken using the obtained protein profiles, a comparative analysis was performed. Results A statistically significant number of proteins (34) were recognized as single biomarker candidate proteins which were differentially detected in the CSF of patients with MMD, compared to the control patients (p < 0.05). All peak intensity profiles of the biomarker candidates underwent classification and regression tree (CART) analysis to produce prediction models. Two important biomarkers could successfully classify the patients with MMD and control patients. Conclusions In this study, several novel biomarker candidate proteins differentially expressed in the CSF of patients with MMD were identified by a recently developed proteomic approach. This is a pilot study of CSF proteomics for MMD using SELDI technology. These biomarker candidates have the potential to shed light on the underlying pathogenesis of MMD.

2010-01-01

323

Mass Spectrometry Video  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry is on the basic principles of mass spectrometry, using a magnetic sector instrument to demonstrate how specific m/z ratios can be selected. The theory and operation of MS, including the chemistry of ionization and fragmentation is described at an introductory level. There is also an excellent example of the use of high resolution MS to differentiate between nominal mass and actual mass. The video does a very good job of explaining the concept such that only a little background knowledge is required. The video is short enough (6 mins), that it would be very useful in a class setting or for students outside of class. The ultimate strength of this video is the general nature of the content that makes it appealing to a wide audience. The video may be most appropriate in a lower-level general education science course (i.e forensic science) or as a quick orientation video for instrumental analysis students prior to introducing mathematical or operational concepts. This video would also be helpful for a lay science person who wishes to learn more about mass spectrometry from a general interest perspective.

2011-06-08

324

Application of sequential paired covariance to capillary electrophoresis electrospray ionization time-of-flight mass spectrometry: Unraveling the signal from the noise in the electropherogram  

SciTech Connect

The combination of capillary electrophoresis (CE) with electrospray ionization (ESI) time-of-flight mass spectrometry (TOF-MS) has recently been demonstrated. When CE is combined with TOF-MS using an electrospray interface, the method provides fast, high-resolution separations with rapid mass analysis and the potential for very high sensitivity. In analyzing the data, one first reconstructs an electropherogram from the data set and then identifies peaks in the mass spectra. The mass spectra corresponding to the peaks in the electropherogram are then inspected to enable solute identification. However, background noise often prevents detection of peaks in the reconstructed electropherogram, thus interfering with the analysis. In this work we demonstrate alternative electropherogram reconstruction techniques that enhance its signal-to-noise ratio, allowing more immediate identification of the number of components in a mixture and their corresponding retention times. The techniques described here should also be adaptable for on-line analysis of CE-ESI-TOF data and the combination with other separation techniques coupled to mass spectrometry (e.g., LC/MS), as well as any multichannel detection scheme. 21 refs., 4 figs., 1 tab.

Muddiman, D.C.; Rockwood, A.L.; Gao, Q.; Severs, J.C.; Udseth, H.R.; Smith, R.D. [Pacific Northwest Lab., Richland, WA (United States); Proctor, A. [GOOGLY Enterprises, Pittsburgh, PA (United States)

1995-12-01

325

Detection of a chemical warfare agent simulant in various aerosol matrixes by ion mobility time-of-flight mass spectrometry.  

PubMed

For the first time, a traditional radioactive nickel (63Ni) beta emission ionization source for ion mobility spectrometry was employed with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer (IM(tof)MS) to detect a chemical warfare agent (CWA) simulant from aerosol samples. Aerosol-phase sampling employed a quartz cyclonic chamber for sample introduction. The simulant reference material, which closely mimicked the characteristic chemical structure of CWAs as defined and described by Schedule 1, 2, or 3 of the Chemical Warfare Convention treaty verification, was used in this study. An overall elevation in arbitrary signal intensity of approximately 1.0 orders of magnitude was obtained by the progressive increase of the thermal AP-IMS temperature from 75 to 275 degrees C. A mixture of one G-type nerve simulant (dimethyl methylphosphonate (DMMP)) in four (water, kerosene, gasoline, diesel) matrixes was found in each case (AP-IMS temperature 75-275 degrees C) to be clearly resolved in less than 2.20 x 10(4) micros using the IM(tof)MS instrument. Corresponding ions, masses, drift times, K(o) values, and arbitrary signal intensities for each of the sample matrixes are reported for the CWA simulant DMMP. PMID:16053290

Steiner, Wes E; Klopsch, Steve J; English, William A; Clowers, Brian H; Hill, Herbert H

2005-08-01

326

Qualitative and Quantitative Analysis of Andrographis paniculata by Rapid Resolution Liquid Chromatography/Time-of-Flight Mass Spectrometry.  

PubMed

A rapid resolution liquid chromatography/time-of-flight tandem mass spectrometry (RRLC-TOF/MS) method was developed for qualitative and quantitative analysis of the major chemical constituents in Andrographis paniculata. Fifteen compounds, including flavonoids and diterpenoid lactones, were unambiguously or tentatively identified in 10 min by comparing their retention times and accurate masses with standards or literature data. The characteristic fragmentation patterns of flavonoids and diterpenoid lactones were summarized, and the structures of the unknown compounds were predicted. Andrographolide, dehydroandrographolide and neoandrographolide were further quantified as marker substances. It was found that the calibration curves for all analytes showed good linearity (R2 > 0.9995) within the test ranges. The overall limits of detection (LODs) and limits of quantification (LOQs) were 0.02 ?g/mL to 0.06 ?g/mL and 0.06 ?g/mL to 0.2 ?g/mL, respectively. The relative standard deviations (RSDs) for intra- and inter-day precisions were below 3.3% and 4.2%, respectively. The mean recovery rates ranged from 96.7% to 104.5% with the relative standard deviations (RSDs) less than 2.72%. It is concluded that RRLC-TOF/MS is powerful and practical in qualitative and quantitative analysis of complex plant samples due to time savings, sensitivity, precision, accuracy and lowering solvent consumption. PMID:24084022

Song, Yong-Xi; Liu, Shi-Ping; Jin, Zhao; Qin, Jian-Fei; Jiang, Zhi-Yuan

2013-09-30

327

End-Group Characterization of Poly(O-benzyl-L-tyrosine) by NALDI-TOF MS  

SciTech Connect

The primary amine initiated polymerization of N-carboxyanhydrides of amino acids (NCAs) has been proposed to proceed by two mechanisms: normal amine mechanism and activated monomer mechanism. Recently, Hadjichristidis et al. showed that high vacuum techniques could be employed to synthesize poly(amino acid)s initiated with primary amines exclusively via the normal amine mechanism. Unfortunately, no end group characterization was reported. Herein we report the end group characterization of the amine-initiated polymerization of the NCA of O-benzyl-L-tyrosine by MALDI-TOF MS and NALDI TM-TOF MS. We show that when synthesized via high vacuum techniques the reaction proceeds exclusively by the normal amine mechanism. The activated monomer mechanism is detected in samples prepared by less rigorous techniques.

Pickel, Deanna L [ORNL; Messman, Jamie M [ORNL; Politakos, Nikolaos [ORNL; Avgeropoulos, Apostolos [ORNL

2009-01-01

328

Analysis of stem cell lipids by offline HPTLC-MALDI-TOF MS  

Microsoft Academic Search

MALDI-TOF MS is traditionally used for “proteomics”, but is also a useful tool for lipid analysis. Depending on the applied\\u000a matrix, however, some lipid classes are more sensitively detected than other ones and this may even lead to suppression effects\\u000a if complex mixtures are analyzed. Therefore, a previous separation into the individual lipid classes is necessary. Using artificial\\u000a lipid mixtures

Beate Fuchs; Jürgen Schiller; Rosmarie Süß; Matthias Zscharnack; Augustinus Bader; Peter Müller; Martin Schürenberg; Michael Becker; Detlev Suckau

2008-01-01

329

SELDI-TOF-MS ProteinChip Array Profiling of Tears from Patients with Dry Eye  

Microsoft Academic Search

METHODS. Patients with dry eye (DRY, n 88) and healthy subjects (CTRL, n 71) were examined. Their tear proteins were analyzed using SELDI-TOF-MS ProteinChip Arrays with three different chromatographic surfaces (CM10 cation ex- change, Q10 anion exchange, and H50 reversed-phase) pre- pared by means of a laboratory liquid-handling robotic work- station. The data were analyzed by multivariate statistical techniques and

Franz H. Grus; Vladimir N. Podust; Kai Bruns; Karl Lackner; Siyu Fu; Enrique A. Dalmasso; Anton Wirthlin; Norbert Pfeiffer

2005-01-01

330

Screening natural antioxidants in peanut shell using DPPH-HPLC-DAD-TOF/MS methods.  

PubMed

Peanut shell, a byproduct in oil production, is rich in natural antioxidants. Here, a rapid and efficient method using DPPH-HPLC-DAD-TOF/MS was used for the first time to screen antioxidants in peanut shell. The method is based on the hypothesis that upon reaction with 1, 1-diphenyl-2-picrylhydrazyl (DPPH), the peak areas of compounds with potential antioxidant activities in the HPLC chromatogram will be significantly reduced or disappeared, and the identity confirmation could be achieved by HPLC-DAD-TOF/MS technique. With this method, three compounds possessing potential antioxidant activities were found abundantly in the methanolic extract of peanut shell. They were identified as 5,7-dihydroxychromone, eriodictyol, and luteolin. The contents of these compounds were 0.59, 0.92, and 2.36 mg/g, respectively, and luteolin possessed the strongest radical scavenging capacity. DPPH-HPLC-DAD-TOF/MS assay facilitated rapid identification and determination of natural antioxidants in peanut shell, which may be helpful for value-added utilization of peanut processing byproducts. PMID:22980814

Qiu, Jiying; Chen, Leilei; Zhu, Qingjun; Wang, Daijie; Wang, Wenliang; Sun, Xin; Liu, Xiaoyong; Du, Fangling

2012-07-15

331

Quantitative biomedical mass spectrometry  

NASA Astrophysics Data System (ADS)

The scope of this contribution is an illustration of the capabilities of isotope dilution mass spectrometry (IDMS) for quantification of target substances in the biomedical field. After a brief discussion of the general principles of quantitative MS in biological samples, special attention will be paid to new technological developments or trends in IDMS from selected examples from the literature. The final section will deal with the use of IDMS for accuracy assessment in clinical chemistry. Methodological aspects considered crucial for avoiding sources of error will be discussed.

de Leenheer, Andrép; Thienpont, Linda M.

1992-09-01

332

Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results  

NASA Astrophysics Data System (ADS)

We present the first eddy covariance flux measurements of volatile organic compounds (VOCs) using a proton-transfer-reaction time-of-flight mass-spectrometer (PTR-TOF-MS) above a ponderosa pine forest in Colorado, USA. The high mass resolution of the PTR-TOF-MS enabled the identification of chemical sum formulas. During a 30 day measurement period in August and September 2010, 649 different ion mass peaks were detected in the ambient air mass spectrum (including primary ions and mass calibration compounds). Eddy covariance with the vertical wind speed was calculated for all ion mass peaks. On a typical day, 17 ion mass peaks including protonated parent compounds, their fragments and isotopes as well as VOC-H+-water clusters showed a significant flux with daytime average emissions above a reliable flux threshold of 0.1 mg compound m-2 h-1. These ion mass peaks could be assigned to seven compound classes. The main flux contributions during daytime (10:00-18:00 LT) are attributed to the sum of 2-methyl-3-buten-2-ol (MBO) and isoprene (50%), methanol (12%), the sum of acetic acid and glycolaldehyde (10%) and the sum of monoterpenes (10%). The total MBO + isoprene flux was composed of 10% isoprene and 90% MBO. There was good agreement between the light and temperature dependency of the sum of MBO and isoprene observed for this work and those of earlier studies. The above canopy flux measurements of the sum of MBO and isoprene and the sum of monoterpenes were compared to emissions calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1). The best agreement between MEGAN 2.1 and measurements was reached using emission factors determined from site specific leaf cuvette measurements. While the modelled and measured MBO + isoprene fluxes agree well the emissions of the sum of monoterpenes is underestimated by MEGAN 2.1. This is expected as some factors impacting monoterpene emissions, such as physical damage of needles and branches due to storms, are not included in MEGAN 2.1. After a severe hailstorm event, 22 ion mass peaks (attributed to six compound classes plus some unknown compounds) showed an elevated flux for the two following days. The sum of monoterpene emissions was 4-23 times higher compared to emissions prior to the hailstorm while MBO emissions remained unchanged. If one heavy storm occurs at this site every month we calculate that the monthly monoterpene emissions (in mg compound m-2) would be underestimated by 40% if this disturbance source is not considered.

Kaser, L.; Karl, T.; Guenther, A.; Graus, M.; Schnitzhofer, R.; Turnipseed, A.; Fischer, L.; Harley, P.; Madronich, M.; Gochis, D.; Keutsch, F. N.; Hansel, A.

2013-06-01

333

Probing the 3-D Structure, Dynamics, and Stability of Bacterial Collagenase Collagen Binding Domain (apo- versus holo-) by Limited Proteolysis MALDI-TOF MS  

PubMed Central

Pairing limited proteolysis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to probe clostridial collagenase collagen binding domain (CBD) reveals the solution dynamics and stability of the protein, as these factors are crucial to CBD effectiveness as a drug-delivery vehicle. MS analysis of proteolytic digests indicates initial cleavage sites, thereby specifying the less stable and highly accessible regions of CBD. Modulation of protein structure and stability upon metal binding is shown through MS analysis of calcium-bound and cobalt-bound CBD proteolytic digests. Previously determined X-ray crystal structures illustrate that calcium binding induces secondary structure transformation in the highly mobile N-terminal arm and increases protein stability. MS-based detection of exposed residues confirms protein flexibility, accentuates N-terminal dynamics, and demonstrates increased global protein stability exported by calcium binding. Additionally, apo- and calcium-bound CBD proteolysis sites correlate well with crystallographic B-factors, accessibility, and enzyme specificity. MS-observed cleavage sites with no clear correlations are explained either by crystal contacts of the X-ray crystal structures or by observed differences between Molecules A and B in the X-ray crystal structures. The study newly reveals the absence of the ?A strand and thus the very dynamic N-terminal linker, as corroborated by the solution X-ray scattering results. Cobalt binding has a regional effect on the solution phase stability of CBD, as limited proteolysis data implies the capture of an intermediate-CBD solution structure when cobalt is bound.

Sides, Cynthia R.; Liyanage, Rohana; Lay, Jackson O.; Philominathan, Sagaya Theresa Leena; Matsushita, Osamu; Sakon, Joshua

2012-01-01

334

HPLC-DAD-Q-TOF-MS/MS analysis and HPLC quantitation of chemical constituents in traditional Chinese medicinal formula Ge-Gen Decoction.  

PubMed

Ge-Gen Decoction (GGD) is a classical formula of traditional Chinese medicine. It is generally used for treating common cold, fever and influenza in China and South East Asia. In this study, a systematic method was established for the qualitative and quantitative analysis of the major constituents in GGD. For qualitative analysis, a method of liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) was developed for identification of multi-constituents. Based on the UV spectra, retention time and MS spectra, sixty compounds in GGD extract were identified or tentatively characterized by comparing with reference substances or literatures. According to the qualitative results, a new quantitative analysis method of GGD was established by HPLC-DAD. Fourteen representative compounds unequivocally identified were chosen as marker components which were derived from five herbs in GGD excluding Zingiberis Rhizoma Recens and Jujubae Fructus. The analytical method was validated through intra- and inter-day precision, repeatability and stability, and the R.S.D. was less than 3.18%, 4.48%, 3.36% and 3.54%, respectively. The LODs and the LOQs for the analytes were less than 1.06 and 3.12?gmL(-1), respectively. The overall recoveries ranged from 94.8% to 105.6%, with the R.S.D. ranging from 0.68% to 3.23%. Then the new method was applied to determine twelve batches of GGD commercial products of three dosage forms. The results indicated that the new approach was applicable in the routine analysis and quality control of GGD products. The study might provide a basis for quality control of GGD, and further study of GGD in vivo. PMID:23584078

Yan, Yan; Chai, Cheng-Zhi; Wang, Da-Wei; Yue, Xin-Yi; Zhu, Dan-Ni; Yu, Bo-Yang

2013-03-26

335

Probing the 3-D Structure, Dynamics, and Stability of Bacterial Collagenase Collagen Binding Domain (apo- versus holo-) by Limited Proteolysis MALDI-TOF MS  

NASA Astrophysics Data System (ADS)

Pairing limited proteolysis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to probe clostridial collagenase collagen binding domain (CBD) reveals the solution dynamics and stability of the protein, as these factors are crucial to CBD effectiveness as a drug-delivery vehicle. MS analysis of proteolytic digests indicates initial cleavage sites, thereby specifying the less stable and highly accessible regions of CBD. Modulation of protein structure and stability upon metal binding is shown through MS analysis of calcium-bound and cobalt-bound CBD proteolytic digests. Previously determined X-ray crystal structures illustrate that calcium binding induces secondary structure transformation in the highly mobile N-terminal arm and increases protein stability. MS-based detection of exposed residues confirms protein flexibility, accentuates N-terminal dynamics, and demonstrates increased global protein stability exported by calcium binding. Additionally, apo- and calcium-bound CBD proteolysis sites correlate well with crystallographic B-factors, accessibility, and enzyme specificity. MS-observed cleavage sites with no clear correlations are explained either by crystal contacts of the X-ray crystal structures or by observed differences between Molecules A and B in the X-ray crystal structures. The study newly reveals the absence of the ?A strand and thus the very dynamic N-terminal linker, as corroborated by the solution X-ray scattering results. Cobalt binding has a regional effect on the solution phase stability of CBD, as limited proteolysis data implies the capture of an intermediate-CBD solution structure when cobalt is bound.

Sides, Cynthia R.; Liyanage, Rohana; Lay, Jackson O.; Philominathan, Sagaya Theresa Leena; Matsushita, Osamu; Sakon, Joshua

2012-03-01

336

Probing the 3-D Structure, Dynamics, and Stability of Bacterial Collagenase Collagen Binding Domain (apo- versus holo-) by Limited Proteolysis MALDI-TOF MS  

NASA Astrophysics Data System (ADS)

Pairing limited proteolysis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to probe clostridial collagenase collagen binding domain (CBD) reveals the solution dynamics and stability of the protein, as these factors are crucial to CBD effectiveness as a drug-delivery vehicle. MS analysis of proteolytic digests indicates initial cleavage sites, thereby specifying the less stable and highly accessible regions of CBD. Modulation of protein structure and stability upon metal binding is shown through MS analysis of calcium-bound and cobalt-bound CBD proteolytic digests. Previously determined X-ray crystal structures illustrate that calcium binding induces secondary structure transformation in the highly mobile N-terminal arm and increases protein stability. MS-based detection of exposed residues confirms protein flexibility, accentuates N-terminal dynamics, and demonstrates increased global protein stability exported by calcium binding. Additionally, apo- and calcium-bound CBD proteolysis sites correlate well with crystallographic B-factors, accessibility, and enzyme specificity. MS-observed cleavage sites with no clear correlations are explained either by crystal contacts of the X-ray crystal structures or by observed differences between Molecules A and B in the X-ray crystal structures. The study newly reveals the absence of the ?A strand and thus the very dynamic N-terminal linker, as corroborated by the solution X-ray scattering results. Cobalt binding has a regional effect on the solution phase stability of CBD, as limited proteolysis data implies the capture of an intermediate-CBD solution structure when cobalt is bound.

Sides, Cynthia R.; Liyanage, Rohana; Lay, Jackson O.; Philominathan, Sagaya Theresa Leena; Matsushita, Osamu; Sakon, Joshua

2011-12-01

337

Dynamically Multiplexed Ion Mobility Time-of-Flight Mass Spectrometry  

SciTech Connect

Ion Mobility Spectrometry–Time-of-Flight Mass Spectrometry (IMS-TOFMS) has been increasingly used in analysis of complex biological samples. A major challenge is to transform IMS-TOFMS to a high-sensitivity high-throughput platform for e.g. proteomics applications. In this work, we have developed and integrated three advanced technologies, enabling (1) efficient ion accumulation in the ion funnel trap prior to IMS separation, (2) multiplexing (MP) of ion packet introduction into the IMS drift tube and (3) signal detection with an analog-to-digital converter (ADC), into the IMS-TOFMS system for the high-throughput analysis of highly complex proteolytic digests of e.g. blood plasma. To better address variable sample complexity, we have additionally developed and rigorously evaluated a new dynamic MP approach that ensures correlation of the analyzer performance with an ion source function, and provides the improved dynamic range and sensitivity. The MP IMS-TOF MS instrument has been shown to reliably detect peptides at a concentration of 1 nM in a highly complex matrix, as well as to provide a four orders of magnitude dynamic range and a mass measurement accuracy of better than 5 ppm. When matched against human blood plasma database, the detected IMS-TOF features yielded ~ 700 unique peptide identifications at a false discovery rate (FDR) of ~ 7.5 %. Accounting for IMS information gave rise to a projected FDR of ~ 4 %. Signal reproducibility was found to be greater than 80 %, while the variations in the number of unique peptide identifications were < 15 %. A single sample analysis was completed in 15 min, corresponding to approximately an order of magnitude improvement compared to a more conventional LC-MS approach.

Belov, Mikhail E.; Clowers, Brian H.; Prior, David C.; Danielson, William F.; Liyu, Andrei V.; Petritis, Brianne O.; Smith, Richard D.

2008-08-01

338

MALDI Imaging Mass Spectrometry  

PubMed Central

A decade after its inception, MALDI imaging mass spectrometry has become a unique technique in the proteomics arsenal for biomarker hunting in a variety of diseases. At this stage of development, it is important to ask whether we can consider this technique to be sufficiently developed for routine use in a clinical setting or an indispensable technology used in translational research. In this report, we consider the contributions of MALDI imaging mass spectrometry and profiling technologies to clinical studies. In addition, we outline new directions that are required to align these technologies with the objectives of clinical proteomics, including: 1) diagnosis based on profile signatures that complement histopathology, 2) early detection of disease, 3) selection of therapeutic combinations based on the individual patient's entire disease-specific protein network, 4) real time assessment of therapeutic efficacy and toxicity, 5) rational redirection of therapy based on changes in the diseased protein network that are associated with drug resistance, and 6) combinatorial therapy in which the signaling pathway itself is viewed as the target rather than any single “node” in the pathway.

Franck, Julien; Arafah, Karim; Elayed, Mohamed; Bonnel, David; Vergara, Daniele; Jacquet, Amelie; Vinatier, Denis; Wisztorski, Maxence; Day, Robert; Fournier, Isabelle; Salzet, Michel

2009-01-01

339

Application of MALDI-TOF mass spectrometry in screening and diagnostic research.  

PubMed

During the last years, mass spectrometry has revolutionised protein biochemistry and has advanced to a superior tool for the identification and detailed analysis of peptides and proteins. The high throughput allowed by some mass spectrometry platforms has enabled the important step from analysis of individual proteins to proteomics. Recently, an additional field of mass spectrometry applications has emerged - namely screening and diagnostic research. In contrast to protein identification, screening applications have to detect analyte molecules of defined molecular weights which can be calculated beforehand, for example by means of chemical structures. Here, the accuracy and sensitivity of mass spectrometry has to be combined with the requirements of high-throughput analyses, in particular speed and automation. These criteria are especially fulfilled by state of the art matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) instruments. The first high throughput screening (HTS) application proved to be genotyping of single nucleotide polymorphisms. The same principle was later applied for several quality control issues, for example for oligonucleotides, peptide or compound libraries. This development has culminated in the screening and profiling of complex biomarker patterns in clinical proteomics to detect a molecular fingerprint for specific diseases in biological samples. Thus, mass spectrometry based methods are expected to enable a very early diagnosis of diseases with minimally invasive methods of investigation. This type of high end screening application has the potential to revolutionise the early diagnosis of many diseases. Here, we give an overview of the application of mass spectrometry in the fields of screening and diagnostic research. PMID:16101460

Pusch, W; Kostrzewa, M

2005-01-01

340

Identification of senkyunolide I metabolites in rats using ultra performance liquid chromatography/quadrupole-time-of-flight tandem mass spectrometry.  

PubMed

Ligusticum chuanxiong Hort. (Umbelliferae) has been widely prescribed to treat cardiovascular disease in China for centuries. Senkyunolide I is one of the major bioactive components in L. chuanxiong, which shows pharmacological activities against migraines and oxidative damage. In this paper, ultra performance liquid chromatography/quadrupole-time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS) was applied for the rapid analysis of senkyunolide I metabolites in rats after its intravenous administration. The non-metabolized parent compound and eighteen metabolites from drug-treated samples in rat plasma, urine and bile were identified. Our analysis indicated that methylation, hydration, epoxidation, glucuronidation and glutathione conjugation were the major pathways of senkyunolide I metabolism in vivo. This study provides important information regarding the metabolism of senkyunolide I, which will be helpful for understanding its mechanism of action. Furthermore, this work demonstrates the potential of using UPLC/Q-TOF-MS for the rapid and reliable characterization of the metabolites of natural products. PMID:23666254

Xiong, Yao-kun; Lin, Xiao; Liang, Shuang; Hong, Yan-long; Shen, Lan; Feng, Yi

2013-04-19

341

Determination of polyamines in human plasma by high-performance liquid chromatography coupled with Q-TOF mass spectrometry.  

PubMed

A high-performance liquid chromatography coupled with Q-time of flight mass spectrometry (HPLC/Q-TOF MS) method was developed and validated for the determination of 1, 3-diaminopropane, putrescine, cadaverine, spermidine and spermine in human plasma. The plasma samples were first pretreated by 10% HClO(4) and then derived by benzoyl chloride with 1, 6-diaminohexane as internal standard. The derived polyamines were separated on a C(18) column using a gradient program. The detection was performed on a Q-TOF MS by positive ionization mode. Calibration curve for each polyamine was obtained in the concentration range of 0.4 ~ 200.0 ng • ml(-1), with limit of detection of 0.02 ~ 0.1 ng • ml(-1). The intra- and inter-day RSD for all polyamines were 2.5-14.0% and 2.9 ~ 13.4%, respectively. The method was applied to determine the polyamines in human plasma from cancer patients and healthy volunteers. Results showed that the mean levels of polyamines in the plasma of cancer patients were higher than that of healthy volunteers, which suggested that the plasma polyamines could be employed as cancer diagnostic indicators in clinical testing. PMID:23019166

Liu, Ran; Bi, Kaishun; Jia, Ying; Wang, Qian; Yin, Ran; Li, Qing

2012-10-01

342

Identification and discrimination of Staphylococcus aureus strains using matrix-assisted laser desorption/ionization-time of flight mass spectrometry.  

PubMed

Staphylococcus aureus is an important human pathogen frequently resistant to a wide range of antibiotics. Methicillin-resistant S. aureus (MRSA) strains are common nosocomial pathogens that pose a world-wide problem. Rapid and accurate discrimination between methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus is essential for appropriate therapeutic management and timely intervention for infection control. We report here the application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for monitoring the bacterial fingerprints expressed by two well characterized S. aureus strains ATCC 29213 (MSSA) and ATCC 43330 (MRSA). Consistent strain-specific data were obtained from subcultures analyzed over a period of three months as well as after changing the growth media from Mueller-Hinton to blood agar indicating the reliability of the method. The bacterial fingerprints of these two strains were compared to independent clinical isolates of S. aureus. A uniform signature profile for MRSA could not be identified. However, the bacterial fingerprints obtained proved to be specific for any given strain. This study demonstrates that MALDI-TOF MS is a powerful method for rapid identification of clonal strains of S. aureus, which might be useful for tracking nosocomial outbreaks of MRSA and for epidemiologic studies of infections diseases in general. PMID:12112858

Bernardo, Katussevani; Pakulat, Norbert; Macht, Marcus; Krut, Oleg; Seifert, Harald; Fleer, Silke; Hünger, Frank; Krönke, Martin

2002-06-01

343

Optimization of the preanalytical steps of matrix-assisted laser desorption ionization-time of flight mass spectrometry identification provides a flexible and efficient tool for identification of clinical yeast isolates in medical laboratories.  

PubMed

We report here that modifications of the preanalytical steps of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification of yeasts, with regard to the original protocol provided by the manufacturers, appear to be efficient for the reliable routine identification of clinical yeast isolates in medical laboratories. Indeed, when one colony was sampled instead of five and the protein extraction protocol was modified, the performance of MALDI-TOF MS was superior to that of the API ID 32C method (discrepancies were confirmed by using molecular identification), allowing the correct identification of 94% of the 335 clinical isolates prospectively tested. We then demonstrated that the time for which the primary cultures were preincubated on CHROMagar did not impact the identification of yeasts by MALDI-TOF MS, since 95.1 and 96.2% of the 183 clinical yeast isolates prospectively tested were correctly identified after 48 and 72 h of preincubation, respectively. PMID:22718939

Goyer, Marianne; Lucchi, Geraldine; Ducoroy, Patrick; Vagner, Odile; Bonnin, Alain; Dalle, Frederic

2012-06-20

344

Mass Spectrometry and Protein Analysis  

NSDL National Science Digital Library

Mass spectrometry is a central analytical technique for protein research and for the study of biomolecules in general. Driven by the need to identify, characterize, and quantify proteins at ever increasing sensitivity and in ever more complex samples, a wide range of new mass spectrometryâÂÂbased analytical platforms and experimental strategies have emerged. Here we review recent advances in mass spectrometry instrumentation in the context of current and emerging research strategies in protein science.

Bruno Domon (ETH Zurich;Institute of Molecular Systems Biology); Ruedi Aebersold (University of Zurich;Faculty of Sciences/Institute of Molecular Systems Biology)

2006-04-14

345

MALDI-based intact spore mass spectrometry of downy and powdery mildews.  

PubMed

Fast and easy identification of fungal phytopathogens is of great importance in agriculture. In this context, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a powerful tool for analyzing microorganisms. This study deals with a methodology for MALDI-TOF MS-based identification of downy and powdery mildews representing obligate biotrophic parasites of crop plants. Experimental approaches for the MS analyses were optimized using Bremia lactucae, cause of lettuce downy mildew, and Oidium neolycopersici, cause of tomato powdery mildew. This involved determining a suitable concentration of spores in the sample, selection of a proper MALDI matrix, looking for the optimal solvent composition, and evaluation of different sample preparation methods. Furthermore, using different MALDI target materials and surfaces (stainless steel vs polymer-based) and applying various conditions for sample exposure to the acidic MALDI matrix system were investigated. The dried droplet method involving solvent evaporation at room temperature was found to be the most suitable for the deposition of spores and MALDI matrix on the target and the subsequent crystallization. The concentration of spore suspension was optimal between 2 and 5?×?10(9) spores per ml. The best peptide/protein profiles (in terms of signal-to-noise ratio and number of peaks) were obtained by combining ferulic and sinapinic acids as a mixed MALDI matrix. A pretreatment of the spore cell wall with hydrolases was successfully introduced prior to MS measurements to obtain more pronounced signals. Finally, a novel procedure was developed for direct mass spectra acquisition from infected plant leaves. PMID:22899506

Chalupová, Jana; Sedlá?ová, Michaela; Helmel, Michaela; Rehulka, Pavel; Marchetti-Deschmann, Martina; Allmaier, Günter; Sebela, Marek

2012-08-01

346

Improved Mass Spectrometry Assay For Plasma Hepcidin: Detection and Characterization of a Novel Hepcidin Isoform  

PubMed Central

Mass spectrometry (MS)-based assays for the quantification of the iron regulatory hormone hepcidin are pivotal to discriminate between the bioactive 25-amino acid form that can effectively block the sole iron transporter ferroportin and other naturally occurring smaller isoforms without a known role in iron metabolism. Here we describe the design, validation and use of a novel stable hepcidin-25+40 isotope as internal standard for quantification. Importantly, the relative large mass shift of 40 Da makes this isotope also suitable for easy-to-use medium resolution linear time-of-flight (TOF) platforms. As expected, implementation of hepcidin-25+40 as internal standard in our weak cation exchange (WCX) TOF MS method yielded very low inter/intra run coefficients of variation. Surprisingly, however, in samples from kidney disease patients, we detected a novel peak (m/z 2673.9) with low intensity that could be identified as hepcidin-24 and had previously remained unnoticed due to peak interference with the formerly used internal standard. Using a cell-based bioassay it was shown that synthetic hepcidin-24 was, like the -22 and -20 isoforms, a significantly less potent inducer of ferroportin degradation than hepcidin-25. During prolonged storage of plasma at room temperature, we observed that a decrease in plasma hepcidin-25 was paralleled by an increase in the levels of the hepcidin-24, -22 and -20 isoforms. This provides first evidence that all determinants for the conversion of hepcidin-25 to smaller inactive isoforms are present in the circulation, which may contribute to the functional suppression of hepcidin-25, that is significantly elevated in patients with renal impairment. The present update of our hepcidin TOF MS assay together with improved insights in the source and preparation of the internal standard, and sample stability will further improve our understanding of circulating hepcidin and pave the way towards further optimization and standardization of plasma hepcidin assays.

Laarakkers, Coby M. M.; Wiegerinck, Erwin T.; Klaver, Siem; Kolodziejczyk, Maria; Gille, Hendrik; Hohlbaum, Andreas M.

2013-01-01

347

Improved mass spectrometry assay for plasma hepcidin: detection and characterization of a novel hepcidin isoform.  

PubMed

Mass spectrometry (MS)-based assays for the quantification of the iron regulatory hormone hepcidin are pivotal to discriminate between the bioactive 25-amino acid form that can effectively block the sole iron transporter ferroportin and other naturally occurring smaller isoforms without a known role in iron metabolism. Here we describe the design, validation and use of a novel stable hepcidin-25(+40) isotope as internal standard for quantification. Importantly, the relative large mass shift of 40 Da makes this isotope also suitable for easy-to-use medium resolution linear time-of-flight (TOF) platforms. As expected, implementation of hepcidin-25(+40) as internal standard in our weak cation exchange (WCX) TOF MS method yielded very low inter/intra run coefficients of variation. Surprisingly, however, in samples from kidney disease patients, we detected a novel peak (m/z 2673.9) with low intensity that could be identified as hepcidin-24 and had previously remained unnoticed due to peak interference with the formerly used internal standard. Using a cell-based bioassay it was shown that synthetic hepcidin-24 was, like the -22 and -20 isoforms, a significantly less potent inducer of ferroportin degradation than hepcidin-25. During prolonged storage of plasma at room temperature, we observed that a decrease in plasma hepcidin-25 was paralleled by an increase in the levels of the hepcidin-24, -22 and -20 isoforms. This provides first evidence that all determinants for the conversion of hepcidin-25 to smaller inactive isoforms are present in the circulation, which may contribute to the functional suppression of hepcidin-25, that is significantly elevated in patients with renal impairment. The present update of our hepcidin TOF MS assay together with improved insights in the source and preparation of the internal standard, and sample stability will further improve our understanding of circulating hepcidin and pave the way towards further optimization and standardization of plasma hepcidin assays. PMID:24124495

Laarakkers, Coby M M; Wiegerinck, Erwin T; Klaver, Siem; Kolodziejczyk, Maria; Gille, Hendrik; Hohlbaum, Andreas M; Tjalsma, Harold; Swinkels, Dorine W

2013-10-04

348

A simple algorithm improves mass accuracy to 50-100 ppm for delayed extraction linear MALDI-TOF mass spectrometry  

SciTech Connect

A simple mathematical technique for improving mass calibration accuracy of linear delayed extraction matrix assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF MS) spectra is presented. The method involves fitting a parabola to a plot of Dm vs. mass data where Dm is the difference between the theoretical mass of calibrants and the mass obtained from a linear relationship between the square root of m/z and ion time of flight. The quadratic equation that describes the parabola is then used to correct the mass of unknowns by subtracting the deviation predicted by the quadratic equation from measured data. By subtracting the value of the parabola at each mass from the calibrated data, the accuracy of mass data points can be improved by factors of 10 or more. This method produces highly similar results whether or not initial ion velocity is accounted for in the calibration equation; consequently, there is no need to depend on that uncertain parameter when using the quadratic correction. This method can be used to correct the internally calibrated masses of protein digest peaks. The effect of nitrocellulose as a matrix additive is also briefly discussed, and it is shown that using nitrocellulose as an additive to a CHCA matrix does not significantly change initial ion velocity but does change the average position of ions relative to the sample electrode at the instant the extraction voltage is applied.

Hack, Christopher A.; Benner, W. Henry

2001-10-31

349

Mass Spectrometric Analysis of Intact Human Monoclonal Antibody Aggregates Fractionated by Size-Exclusion Chromatography  

PubMed Central

ABSTRACT Purpose The aim of this study was to develop a method to characterize intact soluble monoclonal IgG1 antibody (IgG) oligomers by mass spectrometry. Methods IgG aggregates (dimers, trimers, tetramers and high-molecular-weight oligomers) were created by subjecting an IgG formulation to several pH jumps. Protein oligomer fractions were isolated by high performance size exclusion chromatography (HP-SEC), dialyzed against ammonium acetate pH 6.0 (a mass spectrometry-compatible volatile buffer), and analyzed by native electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS). Results Monomeric and aggregated IgG fractions in the stressed IgG formulation were successfully isolated by HP-SEC. ESI-TOF MS analysis enabled us to determine the molecular weight of the monomeric IgG as well as the aggregates, including dimers, trimers and tetramers. HP-SEC separation and sample preparation proved to be necessary for good quality signal in ESI-TOF MS. Both the HP-SEC protocol and the ESI-TOF mass spectrometric technique were shown to leave the IgG oligomers largely intact. Conclusions ESI-TOF MS is a useful tool complementary to HP-SEC to identify and characterize small oligomeric protein aggregates.

Kukrer, Basak; Filipe, Vasco; van Duijn, Esther; Kasper, Piotr T.; Vreeken, Rob J.; Heck, Albert J. R.

2010-01-01

350

Glycomics and Mass Spectrometry  

NASA Astrophysics Data System (ADS)

There is an increasing body of evidence indicating that glycans are implicated in numerous biological processes such as cell-cell interactions, intracellular signaling, and immune response. Glycomics emerges from the necessity to understand the mechanisms underlying the interactions responsible for these activities. The term glycomics is used to describe experimental approaches to studying the structure and function of the glycomes of fluids, cells, tissues, organs etc. Glycomics embraces a variety of technologies amongst which mass spectrometry (MS) plays a pivotal role because it is the method of choice for defining the primary structures of glycopolymers. This chapter provides an insight into MS -based structural strategies that are best suited to studying complex glycomes.

Dell, Anne; Jang-Lee, Jihye; Pang, Poh-Choo; Parry, Simon; Sutton-Smith, Mark; Tissot, Berangere; Morris, Howard R.; Panico, Maria; Haslam, Stuart M.

351

Ultra-performance liquid chromatography coupled with electrospray ionization/quadrupole-time-of-flight mass spectrometry for rapid analysis of constituents of Suanzaoren decoction.  

PubMed

A rapid, sensitive, specific and reliable ultra-performance liquid chromatography coupled with electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS) method with MassLynx™ MassFragment was developed for the analysis of Suanzaoren decoction (SZRD), a Chinese herbal prescription. The analysis was performed on a Waters UPLC BEH C(18) column using gradient elution system. A hyphenated electrospray ionization and Q-TOF analyzer was used for the determination of accurate mass of the protonated or deprotonated molecule and fragment ion in both negative and positive modes. The chromatographic separation was achieved by UPLC, which used a column with 1.7 ?m particle packing which enabled higher speed of analysis, peak capacity, greater resolution and increased sensitivity. The constituents of SZRD were identied and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions, relevant literature and the establishment of an in-house molecular formula database. With this method, a total of 22 compounds of SZTD were tentatively identied based on MS and MS/MS data and comparison with available databases. It is concluded that a rapid and robust platform based on UPLC-ESI-Q-TOF-MS was established, which is useful for identifying multiple-constituent of traditional Chinese medicine (TCM) prescriptions. Our present results proved that the established method could provide helpful chemical information for further pharmacological mechanism research of SZRD. PMID:21994021

Yang, Bo; Dong, Wei; Zhang, Aihua; Sun, Hui; Wu, Fangfang; Wang, Ping; Wang, Xijun

2011-10-12

352

Flow injection mass spectral fingerprints demonstrate chemical differences in rio red grapefruit with respect to year, harvest time, and conventional versus organic farming  

Technology Transfer Automated Retrieval System (TEKTRAN)

Spectral fingerprints were acquired for Ruby Red grapefruit using direct injection-electrospray ionization with time-of-flight and ion trap mass spectrometry (DI-ESI-TOF-MS and DI-ESI-IT-MS). Rio Red grapefruits were harvested 3 times a year (early, mid, and late harvests) in 2005 and 2006 from con...

353

Quantitative characterization of tissue globotetraosylceramides in a rat model of polycystic kidney disease by PrimaDrop sample preparation and indirect high-performance thin layer chromatography-matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry with automated data acquisition.  

PubMed

Glycosphingolipids (GSL) have been associated with a variety of diseases, including cancer and autosomal dominant polycystic kidney disease (ADPKD). In contrast to glucosylceramide and gangliosides, alterations in complex neutral GSLs such as globotetraosylceramide (Gb4Cer) have not been investigated in ADPKD yet, and mass spectrometry analysis of Gb4Cer from tissue extracts remains challenging. To this end, we introduce PrimaDrop as an improved and widely applicable sample preparation method for automated matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) analysis of lipid extracts, which promotes homogeneous cocrystallization and enables relative quantification by indirect thin layer chromatography (TLC)-MALDI-time-of-flight (TOF)-MS against an internal bradykinin standard. Application of the method for detailed investigation of Gb4Cer isoforms in kidneys of an ADPKD rat model revealed increased levels of sphingoid base-containing isoforms in cystic kidneys, whereas changes were subtle for Gb4Cer-containing phytosphingoid bases. We furthermore established an absolute LC-ESI-MS/MS quantification method and demonstrate that absolute quantities of Gb4Cer correlate well with relative quantities obtained by indirect TLC-MALDI-TOF-MS. Taken together, our study proposes an effective sample preparation method for automated analysis of lipid extracts and TLC eluates and suggests that indirect high-performace (HP)TLC-MALDI-TOF-MS with automated data acquisition is a viable option for analysis of neutral glycosphingolipids and that Gb4Cer may play a role in the pathogenesis of ADPKD. PMID:23701631

Ruh, Hermelindis; Sandhoff, Roger; Meyer, Björn; Gretz, Norbert; Hopf, Carsten

2013-06-11

354

Differentiating organic and conventional sage by chromatographic and mass spectrometry flow injection fingerprints combined with principal component analysis.  

PubMed

High-performance liquid chromatography (HPLC) and flow injection electrospray ionization with ion trap mass spectrometry (FIMS) fingerprints combined with principal component analysis (PCA) were examined for their potential in differentiating commercial organic and conventional sage samples. The individual components in the sage samples were also characterized with an ultraperformance liquid chromatograph with a quadrupole-time-of-flight mass spectrometer (UPLC Q-TOF MS). The results suggested that both HPLC and FIMS fingerprints combined with PCA could differentiate organic and conventional sage samples effectively. FIMS may serve as a quick test capable of distinguishing organic and conventional sages in 1 min and could potentially be developed for high-throughput applications, whereas HPLC fingerprints could provide more chemical composition information with a longer analytical time. PMID:23464755

Gao, Boyan; Lu, Yingjian; Sheng, Yi; Chen, Pei; Yu, Liangli Lucy

2013-03-13

355

Structural reinvestigation of the core oligosaccharide of a mutant form of Aeromonas salmonicida lipopolysaccharide containing an O-4 phosphorylated and O-5 substituted Kdo reducing end group using electrospray QqTOF-MS/MS.  

PubMed

The molecular structure of the mutant form of the lipopolysaccharide of Aeromonas salmonicida was determined to contain an O-4 phosphorylated and O-5 substituted Kdo reducing group, and is proposed as the following: [molecular structure: see text] It was established that during the cleavage of this LPS with 1% acetic acid, to release the core oligosaccharide from the Lipid A portion, we obtained a degraded core oligosaccharide which eliminated its phosphate group with extreme facility. The precise molecular structure of this dephosphorylated core was deduced by electrospray mass spectrometry and is proposed as the following:[molecular structure: see text] Low energy collision ESI-QqTOF-MS/MS analysis of the dephosphorylated core oligosaccharide confirmed the presence of the O-5 glycosylated 4,8- and 4,7-anhydro derivatives of the enolizable alpha-keto-acids. The CID tandem mass spectrometric analysis of the heterogeneous mixture of the permethylated core oligosaccharide established the unreported methylation reaction on the diastereomeric 4,8- and 4,7-anhydro alpha-keto-acids and the complete permethylation and addition reaction of the O-5 glycosylated open chain reducing end terminal D-arabino-3-en-2-ulonic acid. The stereo-specific fragmentation routes obtained during the tandem mass spectrometric analysis permitted the precise sequencing of this dephosphorylated rough core oligosaccharide of the mutant LPS of A. salmonicida. PMID:15302978

Banoub, Joseph; Cohen, Alejandro; El Aneed, Anas; LeQuart, Vincent; Martin, Patrick

2004-01-01

356

X-ray sequence ambiguities of Sclerotium rolfsii lectin resolved by mass spectrometry.  

PubMed

X-ray crystallography, although a powerful technique for determining the three-dimensional structure of proteins, poses inherent problems in assigning the primary structure in residues Asp/Asn and Glu/Gln since these cannot be distinguished decisively in the electron density maps. In our recently published X-ray crystal structure of the Sclerotium rolfsii lectin (SRL) at 1.1 A resolution, amino acid sequence was initially deduced from the electron density map and residues Asp/Asn and Glu/Gln were assigned by considering their hydrogen bonding potential within their structural neighborhood. Attempts to verify the sequence by Edman sequencing were not successful as the N terminus of the protein was blocked. Mass spectrometry was applied to verify and resolve the ambiguities in the SRL X-ray crystal structure deduced sequence. From the Matrix assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI TOF-MS) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis of tryptic and chymotryptic peptides of SRL, we could confirm and correct the sequence at five locations with respect to Asp/Asn and Glu/Gln. Analysis data also confirmed the positions of Leu/Ile, Gln/Lys residues and the sequence covering 118 of the total 141 residues accounting to 83.68% of the earlier deduced sequence of SRL. PMID:18163177

Sathisha, G J; Prakash, Y K Subrahmanya; Chachadi, V B; Nagaraja, N N; Inamdar, S R; Leonidas, D D; Savithri, H S; Swamy, B M

2007-12-28

357

Nanopore Mass Spectrometry  

NASA Astrophysics Data System (ADS)

We report on the design, construction, and characterization of a nanopore-based ion source for mass spectrometry. Our goal is to field-extract ions directly from solution into the high vacuum to enable unit collection efficiency and temporal resolution of sequential ion emissions for DNA sequencing. The ion source features a capillary whose tip, measuring tens to hundreds of nanometers in inner diameter, is situated in the vacuum ˜ 1.5 cm away from an extractor electrode. The capillary was filled with conductive solution and voltage-biased relative to the extractor. Applied voltages of hundreds of volts extracted tens to hundreds of nA of current from the tip. A mass analysis of the extracted ions showed primarily singly charged clusters comprising the cation or anion solvated by several solvent molecules. Our interpretation of these results, based on the works of Taylor and of de la Mora, is that the applied electric stresses distort the fluid meniscus into a Taylor cone, where electric fields reach ˜ 1V/nm and induce significant ion evaporation. Accordingly, the abundances of extracted ionic clusters resemble a Boltzmann distribution.

Bush, Joseph; Mihovilovic, Mirna; Maulbetsch, William; Frenchette, Layne; Moon, Wooyoung; Pruitt, Cole; Bazemore-Walker, Carthene; Weber, Peter; Stein, Derek

2013-03-01

358

Quantitative Analysis of Polymer Additives with MALDI-TOF MS Using an Internal Standard Approach  

NASA Astrophysics Data System (ADS)

MALDI-TOF MS is used for the qualitative analysis of seven different polymer additives directly from the polymer without tedious sample pretreatment. Additionally, by using a solid sample preparation technique, which avoids the concentration gradient problems known to occur with dried droplets and by adding tetraphenylporphyrine as an internal standard to the matrix, it is possible to perform quantitative analysis of additives directly from the polymer sample. Calibration curves for Tinuvin 770, Tinuvin 622, Irganox 1024, Irganox 1010, Irgafos 168, and Chimassorb 944 are presented, showing coefficients of determination between 0.911 and 0.990.

Schwarzinger, Clemens; Gabriel, Stefan; Beißmann, Susanne; Buchberger, Wolfgang

2012-06-01

359

Ovarian cancer detection from metabolomic liquid chromatography/mass spectrometry data by support vector machines  

PubMed Central

Background The majority of ovarian cancer biomarker discovery efforts focus on the identification of proteins that can improve the predictive power of presently available diagnostic tests. We here show that metabolomics, the study of metabolic changes in biological systems, can also provide characteristic small molecule fingerprints related to this disease. Results In this work, new approaches to automatic classification of metabolomic data produced from sera of ovarian cancer patients and benign controls are investigated. The performance of support vector machines (SVM) for the classification of liquid chromatography/time-of-flight mass spectrometry (LC/TOF MS) metabolomic data focusing on recognizing combinations or "panels" of potential metabolic diagnostic biomarkers was evaluated. Utilizing LC/TOF MS, sera from 37 ovarian cancer patients and 35 benign controls were studied. Optimum panels of spectral features observed in positive or/and negative ion mode electrospray (ESI) MS with the ability to distinguish between control and ovarian cancer samples were selected using state-of-the-art feature selection methods such as recursive feature elimination and L1-norm SVM. Conclusion Three evaluation processes (leave-one-out-cross-validation, 12-fold-cross-validation, 52-20-split-validation) were used to examine the SVM models based on the selected panels in terms of their ability for differentiating control vs. disease serum samples. The statistical significance for these feature selection results were comprehensively investigated. Classification of the serum sample test set was over 90% accurate indicating promise that the above approach may lead to the development of an accurate and reliable metabolomic-based approach for detecting ovarian cancer.

Guan, Wei; Zhou, Manshui; Hampton, Christina Y; Benigno, Benedict B; Walker, L DeEtte; Gray, Alexander; McDonald, John F; Fernandez, Facundo M

2009-01-01

360

Application of MALDI-TOF mass spectrometry for the detection of enterotoxins produced by pathogenic strains of the Bacillus cereus group.  

PubMed

Enterotoxins produced by different species of the Bacillus cereus group, such as cytotoxin K1 (CytK1) and non-haemolytic enterotoxin (NHE), have been associated with diarrhoeal food poisoning incidents. Detection of CytK1 is not possible with commercial assays while NHE is recognised by an immunological kit (TECRA) that does not specifically target this protein because it is based on polyclonal antibodies. It is evident that the lack of suitable tools for the study of enterotoxins hampers the possibilities for accurate hazard identification and characterisation in microbial food safety risk assessment. We applied matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) for the detection of CytK1 and NHE produced by pathogenic strains of the B. cereus group using protein digests from 1D gel electrophoresis. Secretion of CytK1 and two of the three components of NHE was confirmed in supernatants of different B. cereus cultures. For each protein, we introduce biomarkers that could be used for the screening of food poisoning or food/environmental isolates that can secrete enterotoxins. For example, tryptic peptides of 2,310.2 and 1,192.5 Da (calculated mass) can be indicators for CytK1 and NheA, respectively, although a simultaneous detection of other enterotoxin-specific peptides is recommended to assure the presence of a toxin in an unknown sample. Comparison of MALDI-TOF/MS with the TECRA kit showed that our methodological strategy performed well and it had the competitive advantage of specifically detecting NheA. Therefore, MALDI-TOF/MS can be successfully incorporated into risk assessment procedures in order to determine the involvement of strains of the B. cereus group in foodborne outbreaks, including the recently described cytK1 producing species, Bacillus cytotoxicus. PMID:22875537

Tsilia, Varvara; Devreese, Bart; de Baenst, Ilse; Mesuere, Bart; Rajkovic, Andreja; Uyttendaele, Mieke; Van de Wiele, Tom; Heyndrickx, Marc

2012-08-09

361

Identification of butyrylcholinesterase adducts after inhibition with isomalathion using mass spectrometry: difference in mechanism between (1R)- and (1S)-stereoisomers.  

PubMed

Previous kinetic studies found that butyrylcholinesterase (BChE) inhibited by (1R)-isomalathions readily reactivated, while enzyme inactivated by (1S)-isomers did not. This study tested the hypothesis that (1R)- and (1S)-isomers inhibit BChE by different mechanisms, yielding distinct adducts identifiable by peptide mass mapping with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Equine BChE (EBChE) was inhibited to <10% of control activity with each isomer of isomalathion and the reference compound isoparathion methyl. Control and treated enzyme was digested with trypsin, and peptides were fractionated with HPLC. Separated and unseparated peptides were analyzed with MALDI-TOF-MS. Identity of an organophosphorus peptide adduct was confirmed by fragmentation using postsource decay analysis. EBChE inhibited by (1R)-isomalathions or (S)-isoparathion methyl readily reactivated after oxime treatment with 30-40% activity recovered. Enzyme inactivated by (1S)-isomalathions or (R)-isoparathion methyl recovered <2% and <5% activity, respectively, after oxime treatment. MALDI-TOF-MS analysis revealed that inhibition of EBChE by (1R)-isomalathions and (R)- or (S)-isoparathion methyl yielded O,S-dimethyl phosphate adducts. Enzyme inactivated by (1S)-isomalathions produced only O-methyl phosphate adduct. EBChE modified by (1R)-isomalathions or either enantiomer of isoparathion methyl yielded an O-methyl phosphate adduct as well. The results indicate that EBChE inhibition by (1R)-isomalathions proceeds with loss of diethyl thiosuccinate, but inactivation by (1S)-isomers occurs with loss of thiomethyl as the primary leaving group followed by rapid expulsion of diethyl thiosuccinate to yield an aged enzyme. Furthermore, the data suggest that aging of the O,S-dimethyl phosphate adduct occurs via an S(N)2 process with loss of thiomethyl. PMID:11601883

Doorn, J A; Schall, M; Gage, D A; Talley, T T; Thompson, C M; Richardson, R J

2001-10-15

362

Searching for anthropogenic contaminants in human breast adipose tissues using gas chromatography-time-of-flight mass spectrometry.  

PubMed

The potential of gas chromatography-time-of-flight mass spectrometry (GC-TOF MS) for screening anthropogenic organic contaminants in human breast adipose tissues has been investigated. Initially a target screening was performed for a list of 125 compounds which included persistent halogen pollutants [organochlorine (OC) pesticides, polychlorinated biphenylss (PCBs), polybrominated diphenyl ethers (PBDEs)], polyaromatic hydrocarbons (PAHs), alkylphenols, and a notable number of pesticides from the different fungicide, herbicide and insecticide families. Searching for target pollutants was done by evaluating the presence of up to five representative ions for every analyte, all measured at accurate mass (20-mDa mass window). The experimental ion abundance ratios were then compared to those of reference standards for confirmation. Sample treatment consisted of an extraction with hexane and subsequent normal-phase (NP) High performance liquid chromatography (HPLC) or SPE cleanup. The fat-free LC fractions were then investigated by GC-TOF MS.Full-spectral acquisition and accurate mass data generated by GC-TOF MS also allowed the investigation of nontarget compounds using appropriate processing software to manage MS data. Identification was initially based on library fit using commercial nominal mass libraries. This was followed by comparing the experimental accurate masses of the most relevant ions with the theoretical exact masses with calculations made using the elemental composition calculator included in the software.The application of both target and nontarget approaches to around 40 real samples allowed the detection and confirmation of several target pollutants including p,p'-DDE, hexachlorobenzene (HCB), and some polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Several nontarget compounds that could be considered anthropogenic pollutants were also detected. These included 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) and its metabolite 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO), dibenzylamine, N-butyl benzenesulfonamide (N-BBSA), some naphthalene-related compounds and several PCBs isomers not included in the target list. As some of the compounds detected are xenoestrogens, the methodology developed in this paper could be useful in human breast cancer research. PMID:19097043

Hernández, Félix; Portolés, Tania; Pitarch, Elena; López, Francisco J

2009-01-01

363

Threat Identification in Time of Flight Mass Spectrometry Using Maximum Likelihood.  

National Technical Information Service (NTIS)

A method for determining a threat substance encountered by a time-of-flight mass spectrometer (TOF-MS) using a pre-computed threat library is described. The method comprising the steps of acquiring a spectrum of a test substance, wherein the acquired spec...

C. S. Hayek F. A. Cooch

2004-01-01

364

MALDI-TOF MS proteomic phenotyping of filamentous and other fungi from clinical origin.  

PubMed

Major changes in medical, intensive care and organ transplantation practices are drastically increasing the risk of fungal opportunistic infections. We designed and set-up a MALDI-TOF MS-based assay to identify the most isolated and emerging therapy-refractory/uncommon fungi from cystic fibrosis (CF) and immunocompromised patients. Two-hundred and thirty isolates from 10 different genera (Aspergillus, Emericella, Fusarium, Geosmithia, Neosartorya, Penicillium, Pseudallescheria, Scedosporium, Talaromyces, Fomitopsis), investigated during routine diagnostic efforts, were correlated to 22 laboratory-adapted reference MALDI-TOF MS "proteomic phenotypes". A growth time-course at 30°C on Sabouraud agar medium was performed for the 22 "phenotypes" at 48, 72, 96 and 120h points. The best peptide extraction conditions for full recovery of conidia- or asci-producing multihyphal morph structures and the highest intra- and inter-class profiling correlation were identified for the 120h point spectra dataset, from which an engineered library derived (pre-analytical phase). Fingerprinting classifiers, selected by Wilcoxon/Kruskal-Wallis algorithm, were computed by Genetic Algorithm, Support Vector Machine, Supervised Neuronal Network and Quick Classifier model construction. MS identification (ID) of clinical isolates was referred to genotyping (GT) and, retrospectively, compared to routine morphotyping (MT) IDs (analytical phase). Proteomic phenotyping is revolutionizing diagnostic mycology as fully reflecting species/morph varieties but often overcoming taxonomic hindrance. PMID:22504628

Del Chierico, Federica; Masotti, Andrea; Onori, Manuela; Fiscarelli, Ersilia; Mancinelli, Livia; Ricciotti, Gabriella; Alghisi, Federico; Dimiziani, Leopoldo; Manetti, Cesare; Urbani, Andrea; Muraca, Maurizio; Putignani, Lorenza

2012-04-04

365

Evaluation of matrix-assisted laser desorption/ionization time of flight mass spectrometry for characterization of Culicoides nubeculosus biting midges.  

PubMed

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) has shown promise in species identification of insect species. We evaluated its potential to consistently characterize laboratory-reared biting midges of the species Culicoides nubeculosus (Meigen) (Diptera: Ceratopogonidae). Twenty-one reproducible potential biomarker masses for C. nubeculosus were identified under different experimental treatments. These treatments included the homogenization of insects in either water or known concentrations of formic acid. The biomarker masses were present independent of age, gender and different periods of storage of individuals in 70% ethanol (a standard preservation method). It was found that the presence of blood in females reduced the intensity of the MALDI-TOF pattern, necessitating the removal of the abdomen before analysis. The protein profiles of a related non-biting midge, Forcipomyia sp. (Diptera: Ceratopogonidae), and of Aedes japonicus japonicus (Theobald) (Diptera: Culicidae) mosquitoes were also examined and were distinctly different. These findings provide preliminary data to optimize future studies in differentiation of species within the Culicoides genus using MALDI-TOF MS which is a rapid, simple, reliable and cost-effective technique. PMID:21118284

Kaufmann, C; Ziegler, D; Schaffner, F; Carpenter, S; Pflüger, V; Mathis, A

2010-12-01

366

Characterization of proteins utilized in the desulfurization of petroleum products by matrix-assisted laser desorption ionization time-of-flight mass spectrometry  

SciTech Connect

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF/MS) with delayed extraction is utilized in linear, reflected-ion and post-source decay (PSD) modes to directly characterize enzymes being developed for use in a petroleum desulfurization process. The DNA sequence for the genes isolated from Rhodococcus sp. strain IGTS8 that produce three of the four enzymes under study had been previously reported with a discrepancy in residue assignments for one of the enzymes, dsz-C. The use of proteolytic digests followed by MALDI/TOF/MS with delayed extraction in the reflected-ion mode provided sequence-specific information with mass accuracies exceeding 40 ppm over a range of masses and signal-to-noise values. Peptide mapping of >80% of the residues was accomplished for all four proteins. The use of PSD established the true sequence for dsz-C, resolving the discrepancy in the literature. A posttranslational loss of N-terminal methionine was observed for each of the four proteins in linear MALDI/MS and was reconfirmed by peptide mapping for three of the proteins.

Wolf, B.P.; Sumner, L.W.; Shields, S.J.; Russell, D.H. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry; Nielsen, K.; Gray, K.A. [Energy Biosystems Corp., The Woodlands, TX (United States)

1998-07-01

367

Proteolytic cleavage of glucagon-like peptide-1 by pancreatic beta cells and by fetal calf serum analyzed by mass spectrometry.  

PubMed

Fetal calf serum and a beta-cell line exhibit a proteolytic activity essential for the biological function of glucagon-like peptide-1 (GLP-1). This process of cleavage was investigated using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). To generate processing products, GLP-1 was subjected to rat insulinoma m5F (RINm5F) cell cultures or to fetal calf serum (FCS). For detection of processing products, a standardized extraction method including ion-exchange batch extraction, ultrafiltration, gel filtration, and reversed-phase chromatography was used. The RP fractions were analyzed by MALDI-TOF-MS. Processed proteolytic products were detected by comparing the resulting mass spectra of cell media or FCS after 2 h incubation with GLP-1 (7-36) amide with these of 2 h controls. To perform the comparison of the resulting mass spectra, software (MASSSPECANALYST) based on Microcal Software, Origins C-like language LABTALK was developed. GLP-1 fragments were purified by RP-HPLC, and characterized by sequence analysis. As insulin is the major secretory product of beta cells depending on GLP-1 stimulation, the insulin and insulin fragments of the cell culture supernatants were also analyzed by this method. PMID:10480253

Tammen, H; Forssmann, W G; Richter, R

1999-08-01

368

Rapid, sensitive and simultaneous determination of fluorescence-labeled designated substances controlled by the Pharmaceutical Affairs Law in Japan by ultra-performance liquid chromatography coupled with electrospray-ionization time-of-flight mass spectrometry  

Microsoft Academic Search

A simultaneous determination method based on ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection\\u000a and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed for 16 “designated substances” (Shitei-Yakubutsu)\\u000a controlled by the Pharmaceutical Affairs Law in Japan. These substances were first labeled with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole at 60 °C for 2 h in 0.1 M borax (pH 9.3). The resulting fluorophores\\u000a were well separated by reversed-phase chromatography using

Jun Zhe Min; Suguru Hatanaka; Toshimasa Toyo’oka; Shinsuke Inagaki; Ruri Kikura-Hanajiri; Yukihiro Goda

2009-01-01

369

Rapid and accurate identification of genomic species from the Acinetobacter baumannii (Ab) group by MALDI-TOF MS.  

PubMed

The closely related members of the Acinetobacter baumannii (Ab) group (A. baumannii, A. pittii and A. nosocomialis) are difficult to identify with phenotypic tests in diagnostic laboratories. Genotypic identification methods require special skills and most do not provide rapid results. The aim of this study was to investigate the ability of MALDI-TOF MS to identify members of the Ab group. Sixty epidemiologically unrelated Acinetobacter spp. isolates were investigated by MALDI-TOF MS: 18 A. baumannii, 17 A. pittii, 18 A. nosocomialis and seven additional isolates representing other Acinetobacter spp. All strains were verified by ARDRA, rRNA intergenic spacer (ITS), recA sequencing and bla(OXA-51) . MALDI-TOF MS correctly identified all the genomic strains but erroneously identified A. nosocomialis as A. baumannii because there was no reference strain within the Bruker database. Peak analysis of individual spectra from representative strains of each member of A. baumannii, A. pittii and A. nosocomialis suggested enough differences between their protein signatures to allow accurate identification using MALDI-TOF MS. Inclusion of specific signature profiles for A. nosocomialis within the Bruker database allowed the correct identification of this genomic species. MALDI-TOF MS spectra can be used as a fast, simple and reliable method to identify members of the Ab group. The rapid and accurate identification of clinically significant Acinetobacter strains will improve insight into their epidemiology and allow for targeted therapeutic and infection control measures against clinically important strains. PMID:22085042

Espinal, P; Seifert, H; Dijkshoorn, L; Vila, J; Roca, I

2011-11-15

370

Analysis of Alphalactalbumin and Betalactoglobulin from the Rehydration of Bovine Colostrum Powder Using Cloud Point Extraction and Mass Spectrometry  

PubMed Central

Alphalactalbumin (?-La) and betalactoglobulin (?-Lg) in the rehydration of bovine colostrum powder were successfully separated by cloud point extraction using a nonionic surfactant Triton X-114. The effects of different factors, including the surfactant concentration, sample volume, electrolyte, and pH were discussed. The optimized conditions for cloud point extraction of alphalactalbumin (?-La) and betalactoglobulin (?-Lg) can be concluded that the best surfactant is 1% (w/v) Triton X-114, 200 ?L of sample volume, 150 mmol/L NaCl, and 6% (w/v) sucrose. After cloud point extraction, the capillary electrophoresis is used to check the efficiency of the extraction procedure. The results had been effectively confirmed by the characterization with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS).

Zhang, Fan; Qi, Xiaohua; Zou, Mingqiang; Li, Jinfeng

2012-01-01

371

Breakthrough bacteremia due to Clostridium tertium in a patient with neutropenic fever, and identification by MALDI-TOF mass spectrometry.  

PubMed

Clostridium tertium is rare in a human clinical specimen and its pathogenicity is often uncertain. However, the organism has been increasingly recognized as a cause of bacteremia and other infections in immunocompromised patients, especially those with hematologic malignancies. The diagnosis and treatment of C. tertium are difficult due to its growth pattern, micromorphology, and antibiotic resistance. The organism can easily be misidentified as Gram-positive aerobic rods such as Bacillus species, usually considered as a contaminant. Furthermore, it is not covered by empirical treatment with many broad-spectrum antibiotics. Here we report a case of breakthrough bacteremia due to C. tertium that occurred in a patient with acute leukemia and neutropenic fever, who was treated with an empirical regimen of ceftazidime and amikacin. The bacterium was rapidly identified by new mass spectrometry technology (MALDI-TOF MS) and the patient recovered under meropenem and vancomycin treatment, without complications. PMID:23823278

Salvador, Francisco; Porte, Lorena; Durán, Luisa; Marcotti, Alejandra; Pérez, Jorge; Thompson, Luis; Noriega, Luis Miguel; Lois, Vivianne; Weitzel, Thomas

2013-04-26

372

Pseudotargeted metabolomics method and its application in serum biomarker discovery for hepatocellular carcinoma based on ultra high-performance liquid chromatography/triple quadrupole mass spectrometry.  

PubMed

Untargeted analysis performed using full-scan mass spectrometry (MS) coupled with liquid chromatography (LC) is commonly used in metabolomics. Although they are commonly employed, full-scan MS methods such as quadrupole-time-of-flight (Q-TOF) MS have been restricted by various factors including their limited linear range and complicated data processing. LC coupled with triple quadrupole (QQQ) MS operated in the multiple reaction monitoring (MRM) mode is the gold standard for metabolite quantification; however, only known metabolites are generally quantified, limiting its applications in metabolomic analysis. In this study, a pseudotargeted approach was proposed to perform serum metabolomic analysis using an ultra high-performance liquid chromatography (UHPLC)/QQQ MS system operated in the MRM mode, for which the MRM ion pairs were acquired from the serum samples through untargeted tandem MS using UHPLC/Q-TOF MS. The UHPLC/QQQ MRM MS-based pseudotargeted method displayed better repeatability and wider linear range than the traditional UHPLC/Q-TOF MS-based untargeted metabolomics method, and no complicated peak alignment was required. The developed method was applied to discover serum biomarkers for patients with hepatocellular carcinoma (HCC). Patients with HCC had decreased lysophosphatidylcholine, increased long-chain and decreased medium-chain acylcarnitines, and increased aromatic and decreased branched-chain amino acid levels compared to healthy controls. The novelty of this work is that it provides an approach to acquire MRM ion pairs from real samples, is not limited to metabolite standards, and it provides a foundation to achieve pseudotargeted metabolomic analysis on the widely used LC/QQQ MS platform. PMID:23889541

Chen, Shili; Kong, Hongwei; Lu, Xin; Li, Yong; Yin, Peiyuan; Zeng, Zhongda; Xu, Guowang

2013-08-14

373

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for detection and identification of albumin phosphylation by organophosphorus pesticides and G- and V-type nerve agents  

Microsoft Academic Search

Toxic organophosphorus compounds (OPC), e.g., pesticides and nerve agents (NA), are known to phosphylate distinct endogenous\\u000a proteins in vivo and in vitro. OPC adducts of butyrylcholinesterase and albumin are considered to be valuable biomarkers for\\u000a retrospective verification of OPC exposure. Therefore, we have detected and identified novel adducts of human serum albumin\\u000a (HSA) by means of matrix-assisted laser desorption\\/ionization time-of-flight

Harald John; Felicitas Breyer; Jörg Oliver Thumfart; Hans Höchstetter; Horst Thiermann

2010-01-01

374

Optimal extraction and fingerprint analysis of Cnidii fructus by accelerated solvent extraction and high performance liquid chromatographic analysis with photodiode array and mass spectrometry detections.  

PubMed

A confirmatory and reliable procedure has been developed for extraction and determination of Cnidii fructus by accelerated solvent extraction (ASE) and high-performance liquid chromatography coupled with photodiode array, electrospray ionisation ion trap tandem mass spectrometry and time of flight mass spectrometry (HPLC-PDA-ESI-ITMS(n)/TOF-MS). The determination method enabled the characterisation of sixteen bioactive components in C. fructus and quantification of three major coumarins, namely osthole, imperatorin and isopimpinellin. Response surface methodology (RSM) was employed to optimise the extraction parameters yielding the optimum conditions of ASE (extraction temperature 122 °C, extraction time 5 min and two static cycles). And the total contents of three major coumarins extracted by ASE under the optimum conditions was significantly higher than those by reflux and ultrasonic extraction (P<0.05) with better reproducibility. At last, the proposed method coupled with pattern recognition was applied to analysis of C. fructus from eight different regions in China. PMID:23870916

Gao, Fangyuan; Hu, Yongsheng; Ye, Xiaolan; Li, Ji; Chen, Zhao; Fan, Guorong

2013-05-21

375

Laser-induced variable pulse-power TOF-MS and neutral time-of-flight studies of ultradense deuterium  

NASA Astrophysics Data System (ADS)

The ultradense atomic deuterium material named D(-1) is conveniently studied by laser-induced Coulomb explosion methods. A well-defined high kinetic energy release (KER) from this material was first reported in Badiei et al (2009 Int. J. Hydrog. Energy 34 487) and a two-detector setup was used to prove the high KER and the complex fragmentation patterns in Badiei et al (2009 Int. J. Mass Spectrom. 282 70). The common KER is 630 ±30 eV, which corresponds to an interatomic distance D-D of 2.3 ±0.1 pm. In both ion and neutral time-of-flight (TOF) measurement, two similar detectors at widely different flight distances prove that atomic particles are observed. New results on neutral TOF spectra are now reported for the material D(-1). It is shown that density changes of D(-1) are coupled to similar changes in ordinary dense D(1), and it is proposed that these two forms of dense deuterium are rapidly transformed into each other. The TOF-MS signal dependence on the intensity of the laser is studied in detail. The fast deuteron intensity is independent of the laser power over a large range, which suggests that D(-1) is a superfluid with long-range efficient transport of excitation energy or particles.

Badiei, Shahriar; Andersson, Patrik U.; Holmlid, Leif

2010-04-01

376

Mass spectrometry of fatty aldehydes  

Microsoft Academic Search

Fatty aldehydes are important components of the cellular lipidome. Significant interest has been developed towards the analysis of the short chain ?,?-unsaturated and hydroxylated aldehydes formed as a result of oxidation of polyunsaturated fatty acids. Multiple gas chromatography–mass spectrometry (GC\\/MS) and subsequently liquid chromatography–mass spectrometry (LC\\/MS) approaches have been developed to identify and quantify short-chain as well as long-chain fatty

Evgeny V. Berdyshev

2011-01-01

377

Analysis of trace organic compounds in vehicle emission using REMPI/TOF-MS  

NASA Astrophysics Data System (ADS)

Emission of fuel combustion in vehicle engines is one of the most important sources of urban environmental pollution. In this paper we present a new method for detecting trace pollution gases of vehicle emissions - laser mass spectrometry. The principles of the laser mass spectrometry is combination of resonant enhanced multiphoton ionization with flight-of-time mass spectroscopy. The experimental setup and results on the exhaust gas of a motorcycle are detailed. By excitation of 248nm KrF excimer laser, benzene and other aromatic compounds are detected in the motorcycle exhaust gases. The preliminary results of the concentration change of these compounds with speed are also presented.

Li, Ziyao; Wei, Jie; Xia, Zhuhong; Gu, Xuejun; Zhang, Liandi; Kong, Xianghe; Zheng, Haiyang; Zhang, Bing

2000-10-01

378

Toward the Complete Characterization of Atmospheric Organic Particulate Matter: Derivatization and Two-Dimensional Comprehensive Gas Chromatography/Time of Flight Mass Spectrometry as a Method for the Determination of Carboxylic Acids  

NASA Astrophysics Data System (ADS)

Understanding the composition of atmospheric organic particulate matter (OPM) is essential for predicting its effects on climate, air quality, and health. However, the polar oxygenated fraction (PO-OPM), which includes a significant mass contribution from carboxylic acids, is difficult to speciate and quantitatively determine by current analytical methods such as gas chromatography-mass spectrometry (GC-MS). The method of chemical derivatization and two-dimensional GC with time of flight MS (GCxGC/TOF-MS) was examined in this study for its efficacy in: 1) quantifying a high percentage of the total organic carbon (TOC) mass of a sample containing PO-OPM; 2) quantitatively determining PO-OPM components including carboxylic acids at atmospherically relevant concentrations; and 3) tentatively identifying PO-OPM components. Two derivatization reagent systems were used in this study: BF3/butanol for the butylation of carboxylic acids, aldehydes, and acidic ketones, and BSTFA for the trimethylsilylation (TMS) of carboxylic acids and alcohols. Three alpha-pinene ozonolysis OPM filter samples and a set of background filter samples were collected by collaborators in a University of California, Riverside environmental chamber. Derivatization/GCxGC TOF-MS was used to tentatively identify some previously unidentified ?-pinene ozonolysis products, and also to show the characteristics of all oxidation products determined. Derivatization efficiencies as measured were 40-70% for most butyl derivatives, and 50-58% for most trimethylsilyl derivatives. A thermal optical method was used to measure the TOC on each filter, and a value of the quantifiable TOC mass using a gas chromatograph was calculated for each sample using GCxGC separation and the mass-sensitive response of a flame ionization detector (FID). The TOC quantified using TMS and GCxGC-FID (TMS/TOCGCxGC FID) accounted for 15-23% of the TOC measured by the thermal-optical method. Using TMS and GCxGC/TOF-MS, 8.85% of the thermal optical TOC was measured and 48.2% of the TMS/TOCGCxGC-FID was semi-quantified using a surrogate standard. The carboxylic acids tentatively identified using TMS and GCxGC/TOF-MS accounted for 8.28% of the TOC measured by thermal optical means. GCxGC TOF-MS chromatograms of derivatized analytes showed reduced peak tailing due in part to the lesser interactions of the derivatized analytes with the stationary phase of the chromatography column as compared to the chromatograms of underivatized samples. The improved peak shape made possible the greater separation, quantification, and identification of high polarity analytes. Limits of detection using derivatization and GCxGC/TOF-MS were <1 ng per ?L injected for a series of C2-C6 di-acids, cis-pinonic acid, and dodecanoic acid using both butylation and TMS. Derivatization with GCxGC/TOF-MS was therefore effective for determining polar oxygenated compounds at low concentrations, for determining specific oxidation products not previously identified in OPM, and also for characterizing the probable functional groups and structures of ?-pinene ozonolysis products.

Boris, Alexandra Jeanne

379

Simultaneous qualitative and quantitative analysis of phenolic acids and flavonoids for the quality control of Apocynum venetum L. leaves by HPLC-DAD-ESI-IT-TOF-MS and HPLC-DAD.  

PubMed

A reliable method based on high performance liquid chromatography-diode array detector-electrospray ionization-ion trap-time of flight-mass spectrometry (HPLC-DAD-ESI-IT-TOF-MS) was developed for the identification of phenolic acids and flavonoids in Apocynum venetum L. leaves and its adulterant, Pocynum hendersonii (Hook. f.) Woodson leaves. A total of 21 compounds were identified or tentatively identified, including 4 phenolic acids and 17 flavonoids. 3-O-caffeoylquinic acid (3-CQA) and caffeic acid were detected for the first time in A. venetum leaves; 4-O-caffeoylquinic acid (4-CQA), 3-CQA, caffeic acid, quercetin-3-O-(6"-O-malonyl)-galactoside, quercetin-3-O-(6"-O-malonyl)-glucoside, kaempferol-3-O-(6"-O-malonyl)-glucoside, kaempferol-3-O-(6"-O-acetyl)-glucoside, and kaempferol-3-O-dihexoside were detected for the first time in P. hendersonii leaves. Cluster analysis was employed to analyze 24 batches of A. venetum leaves and 5 batches of P. hendersonii leaves collected from various regions in China. The analysis, which was based on the 21 compounds, indicated that profiles of these compounds were distinct between the two species, and among A. venetum leaf samples from different origins. 18 of these 21 compounds were selected as the markers and simultaneously analyzed by HPLC-DAD for the first time. The quantitative analytical method was validated and subsequently applied to the comprehensive quality evaluation of 24 batches of A. venetum leaves. PMID:23973760

An, Haijuan; Wang, Hong; Lan, Yuexiang; Hashi, Yuki; Chen, Shizhong

2013-07-19

380

Mass spectrometric analysis of peptides in brain neurosecretory cells and neurohemal organs in the adult blowfly, Protophormia terraenovae  

Microsoft Academic Search

Neuropeptides in neurosecretory cells of the pars intercerebralis (PI) and pars lateralis (PL) in the brain, and those in the corpus cardiacum–hypocerebral ganglion complex (CC-HG) and corpus allatum (CA) were examined by mass spectrometry and immunocytochemistry in adult females of the blowfly, Protophormia terraenovae. By using matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and electrospray ionization quadrupole orthogonal acceleration

Aoi Inosaki; Akikazu Yasuda; Tetsuro Shinada; Yasufumi Ohfune; Hideharu Numata; Sakiko Shiga

2010-01-01

381

Optimization of Matrix-Assisted-Laser-Desorption-Ionization-Time-Of-Flight Mass Spectrometry for the identification of bacterial contaminants in beverages.  

PubMed

The growth of microbial contaminants in industrially produced beverages can cause turbidity, haze and off-flavors resulting in quality loss often rendering the product undrinkable. In this work Matrix-Assisted-Laser-Desorption-Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) based on the generation of peptide mass fingerprints, which form a distinctive protein peak pattern, is presented as a rapid, reliable and powerful tool for the identification of spoilage bacteria encountered in beverages. Lactobacillus brevis, Pediococcus claussenii and Leuconostoc mesenteroides were used to optimize sample preparation and MALDI-TOF MS-settings. Different sample preparation methods ranging from plain cell smears to more elaborate extraction procedures including mechanical and enzymatical disruption of cells were investigated. The effects of culturing time and the availability of oxygen and nutrients on the acquired protein peak patterns were studied. While cell smears at times hampered the acquisition of spectra for strain L. brevis all other procedures constantly delivered good quality spectra for all three strains. The extraction procedure allowed good reproducibility of spectra with high information content and enabled differentiation on the species level regardless of the culture conditions used. The application of specific culture conditions to microorganisms resulted in minor but stable changes in spectra, which were not sufficient to impair identification of isolates on the species level. PMID:23541955

Kern, Carola C; Usbeck, Julia C; Vogel, Rudi F; Behr, Jürgen

2013-03-26

382

Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry profiling of trace constituents of condom lubricants in the presence of biological fluids.  

PubMed

The use of condoms in sexual assault cases has become increasingly common due to the heightened awareness of the use of DNA as evidence in criminal investigations. The ability to identify and differentiate the polymers and additives found in lubricant residues can provide investigators leads and insights as to the perpetrator of a sexual assault. Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) is ideal for detecting condom lubricants and additives; the instrument is capable of surveying analytes across a wide mass range and is a preferred technique for the analysis of polymers. Three MALDI-TOF-MS methods directed toward the detection and differentiation of condom and personal lubricant residues, as well as their mixtures with biological fluids, were developed and compared: (a) a sample premixed with aqueous matrix; (b) a sample premixed with an ionic liquid matrix; and (c) a layering method that incorporates a cationization reagent. Of the three, the layered method that utilized sodium chloride as a cationization reagent showed the best sensitivity and selectivity. This method allowed for the segregation of the various lubricant formulas into a discrete number of groups. Infrared spectroscopy was used to support and clarify the MALDI data. Principal component analysis was used to further demonstrate the ability of this method to segregate various lubricant types into a limited number of classes. Additionally, lubricant residues could be detected in the presence of biological fluids down to a fraction of a percent. PMID:20832207

Spencer, Sandra E; Kim, Sin Young; Kim, Seoung Bum; Schug, Kevin A

2010-09-15

383

Use of time-of-flight mass spectrometry for large screening of organic pollutants in surface waters and soils from a rice production area in Colombia.  

PubMed

The irrigate district of Usosaldaña, an important agricultural area in Colombia mainly devoted to rice crop production, is subjected to an intensive use of pesticides. Monitoring these compounds is necessary to know the impact of phytosanitary products in the different environmental compartments. In this work, surface water and soil samples from different sites of this area have been analyzed by applying an analytical methodology for large screening based on the use of time-of-flight mass spectrometry (TOF MS) hyphenated to liquid chromatography (LC) and gas chromatography (GC). Several pesticides were detected and unequivocally identified, such as the herbicides atrazine, diuron or clomazone. Some of their main metabolites and/or transformation products (TPs) like deethylatrazine (DEA), deisopropylatrazine (DIA) and 3,4-dichloroaniline were also identified in the samples. Among fungicides, carbendazim, azoxystrobin, propiconazole and epoxiconazole were the most frequently detected. Insecticides such as thiacloprid, or p,p'-DDT metabolites (p,p'-DDD and p,p'-DDE) were also found. Thanks to the accurate-mass full-spectrum acquisition in TOF MS it was feasible to widen the number of compounds to be investigated to other families of contaminants. This allowed the detection of emerging contaminants, such as the antioxidant 3,5-di-tertbutyl-4-hydroxy-toluene (BHT), its metabolite 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), or the solar filter benzophenone, among others. PMID:23085466

Hernández, F; Portolés, T; Ibáñez, M; Bustos-López, M C; Díaz, R; Botero-Coy, A M; Fuentes, C L; Peñuela, G

2012-10-17

384

[Screening method for multi herbicide and insecticide residues in soybeans using high performance liquid chromatography-time-of-flight mass spectrometry].  

PubMed

A new multi-residue methodology using liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) for the quantitative analysis of pesticides has been developed. The analytical performance of the method was evaluated by screening herbicide and insecticide residues in 10 kinds of imported soybeans. The accurate mass was obtained in different spiking levels (from 0.05 to 0.10 mg/kg) and the accuracy error was lower than 3 x 10(-6), which is well within the accepted limits for target confirmation. The linearity of response ranged from 0.03 mg/kg to 1.0 mg/kg and the correlation coefficient was greater than 0.99. The average recoveries of herbicides and insecticides ranged from 60% to 120% of the fortified herbicides and insecticides in soybeans at 0.05 - 0.10 mg/kg levels for the majority of herbicides and insecticides, and the relative standard deviations (RSD) were between 2.17% and 13.54%. The limits of detection (LOD) were between 0.002 and 0.026 mg/kg. The results indicated that the method developed is easier, faster, and more sensitive. It also demonstrated that this method can meet the requirements for simultaneous determination of herbicides and insecticides in soybeans. This study provides valuable evidence for that LC-TOF-MS method has the potential in screening multi pesticide residues in soybeans. PMID:18257315

Chu, Xiaogang; Yong, Wei; Ling, Yun; Yao, Huiyuan; Zweigenbaum, Jerry; Fang, Yanyan

2007-11-01

385

Mass spectrometry of proton adducts of fucosylated N-glycans: fucose transfer between antennae gives rise to misleading fragments.  

PubMed

Fragmentation behavior of fucosylated N-glycans in both protonated and sodiated form was studied by low-energy collision-induced dissociation with an ion trap mass spectrometer as well as by laser-induced dissociation with matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). Diantennary, core-(alpha1-6)-fucosylated N-glycans with Lewis X (Gal(beta1-4)[Fuc(alpha1-3)]GlcNAcbeta1-) and/or fucosylated LacdiNAc antennae (GalNAc(beta1-4)[Fuc(alpha1-3)]GlcNAcbeta1-) were obtained from the human parasite Schistosoma mansoni and used as model substances, after labeling with 2-aminobenzamide, or as native reducing glycans. While fragment spectra of sodiated as well as protonated species obtained in both mass spectrometers resulted in B- and Y-type ions, fragmentation of proton adducts additionally gave rise to various fragment ions which had acquired fucose residues from other parts of the molecule. In particular, fucose was transferred efficiently to the Lewis X antennae suggesting the occurrence of difucosylated antennae, which could erroneously be interpreted as Lewis Y epitopes. By studying two additional model substances, this fucose gain was shown to occur by transfer of fucose between the antennae, but not by transfer of a core-(alpha1-6)-fucose. Despite the drastically different lifetimes of the ions, protonated species analyzed on the ion trap (millisecond range) and by MALDI-TOF/TOF-MS (microsecond range) showed similar rearrangement patterns, suggesting that the fucose mobility goes hand in hand with decomposition. Notably, permethylation of the model N-glycans seemed to completely preclude fucose migration. This study indicates that caution should be applied with the interpretation of tandem mass spectrometric (MS/MS) data of protonated glycoconjugates, including glycopeptides, because of the potential occurrence of fucose rearrangements. PMID:16676317

Wuhrer, Manfred; Koeleman, Carolien A M; Hokke, Cornelis H; Deelder, André M

2006-01-01

386

Surface preparation strategies for improved parallelization and reproducible MALDI-TOF MS ligand binding assays.  

PubMed

Immunoassays are employed in academia and the healthcare and biotech industries for high-throughput, quantitative screens of biomolecules. We have developed monolayer-based immunoassays for MALDI-TOF MS. To improve parallelization, we adapted the workflow to photolithography-generated arrays. Our work shows Parylene-C coatings provide excellent "solvent pinning" for reagents and biofluids, enabling sensitive MS detection of immobilized components. With a unique MALDI-matrix crystallization technique we show routine interassay RSD <10% at picomolar concentrations and highlight platform compatibility for relative and label-free quantitation applications. Parylene-arrays provide high sample densities and promise screening throughputs exceeding 1000 samples/h with modern liquid-handlers and MALDI-TOF systems. PMID:23249094

Roth, Michael J; Maresh, Erica M; Plymire, Daniel A; Zhang, Junmei; Corbett, John R; Robbins, Roger; Patrie, Steven M

2012-12-24

387

Instrumentation for mass spectrometry: 1997  

SciTech Connect

All mass spectrometry experiments involve the manipulation of material, an interface with the mass spectrometer, ionization, ion manipulation/analysis, detection and data collection/reduction. Each of these elements involve instrumentation. The wide range of species now amenable to mass spectrometry and the diverse areas of physical science in which it plays a role have led to a seemingly unlimited array of instrumental combinations. However, only a limited number of mass analyzers, and their combinations, dominate. The dominant analyzers include time-of-flight, Fourier transform ion cyclotron resonance, the Paul trap, the mass filter, and the sector mass spectrometer. Why there are so few (or so many, depending upon one`s point of view) can be understood upon consideration of a set of mass analyzer figures of merit. These include mass resolution, mass accuracy, mass range, dynamic range, abundance sensitivity, precision, efficiency, speed, MS{sup n} capability, compatibility with the ionizer, cost, and size. The most appropriate form of mass spectrometry is determined by the priorities of the particular measurement placed on the various mass analyzer characteristics and the relative strengths of the analyzers in meeting the requirements. Each of the analyzer types has a unique set of figures of merit that makes it optimally suited for particular applications. This paper discusses these figures of merit, provides data illustrating recent developments for each analyzer type, and gives the figures of merit of each type of analyzer as they stand in 1997. 101 refs., 24 figs.

McLuckey, S.A.

1997-08-01

388

Development and characterization of cIEF-MALDI-TOF MS for protein analysis.  

PubMed

This paper describes the hyphenation of cIEF and MALDI-TOF MS via a fractionation or spotting device. After focusing in cIEF the compounds are hydrodynamically mobilized and deposited on a MALDI target plate using a sheath liquid interface, which provides the catholyte solution and the electrical ground. From previous experiments, sample conditions that resulted in a high resolution in cIEF and acceptable protein signal intensity in MS were selected [Silvertand et al., Electrophoresis, 2008, 29, 1985-1996]. Besides the mixture of test proteins, the sample solution contains 1% Pharmalyte, 0.3% hydroxyethyl cellulose and 0.1% Tween 20 and is used for both optimization as well as characterization of the cIEF-MALDI-TOF MS system. Hyphenation problems encountered are mainly due to transfer of the liquid from the needle to the MALDI target plate and are solved by choosing the proper sheath catholyte (200 mM NH4OH in 50% methanol with 0.1% Tween20). MS electropherograms were reconstructed by plotting the intensities of the m/z values corresponding to the proteins versus migration time (related to spot number). Reproducibility, peak width and signal intensity for different focusing and spotting (fractionation) times were calculated using these reconstructed MS electropherograms as well as the UV electropherograms. The best results were obtained with focusing time of 75 min (no under- or overfocusing) and a spotting time of 5 s (highest protein signal intensity in MS). The applicability of the system is demonstrated by the analysis of a biopharmaceutical (glucagon) and its deamidation product. PMID:19391148

Silvertand, Linda H H; Toraño, Javier Sastre; de Jong, Gerhardus J; van Bennekom, Wouter P

2009-05-01

389

Method for Screening and MALDI-TOF MS Sequencing of Encoded Combinatorial Libraries  

PubMed Central

We describe a new method for encoded synthesis, efficient on-resin screening, and rapid unambiguous sequ