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1

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

2

Feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) networking in university hospitals in Brussels.  

PubMed

The mutualisation of analytical platforms might be used to address rising healthcare costs. Our study aimed to evaluate the feasibility of networking a unique matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) system for common use in several university hospitals in Brussels, Belgium. During a one-month period, 1,055 successive bacterial isolates from the Brugmann University Hospital were identified on-site using conventional techniques; these same isolates were also identified using a MALDI-TOF MS system at the Porte de Hal Laboratory by sending target plates and identification projects via transportation and the INFECTIO_MALDI software (Infopartner, Nancy, France), respectively. The occurrence of transmission problems (<2 %) and human errors (<1 %) suggested that the system was sufficiently robust to be implemented in a network. With a median time-to-identification of 5 h and 11 min (78 min, min-max: 154-547), MALDI-TOF MS networking always provided a faster identification result than conventional techniques, except when chromogenic culture media and oxidase tests were used (p < 0.0001). However, the limited clinical benefits of the chromogenic culture media do not support their extra cost. Our financial analysis also suggested that MALDI-TOF MS networking could lead to substantial annual cost savings. MALDI-TOF MS networking presents many advantages, and few conventional techniques (optochin and oxidase tests) are required to ensure the same quality in patient care from the distant laboratory. Nevertheless, such networking should not be considered unless there is a reorganisation of workflow, efficient communication between teams, qualified technologists and a reliable IT department and helpdesk to manage potential connectivity problems. PMID:24197439

Martiny, D; Cremagnani, P; Gaillard, A; Miendje Deyi, V Y; Mascart, G; Ebraert, A; Attalibi, S; Dediste, A; Vandenberg, O

2014-05-01

3

An overview of analytical applications of time of flight-mass spectrometric (TOF-MS) analyzers and an inductively coupled plasma-TOF-MS technique.  

PubMed

A brief overview of the applications of time-of-flight mass spectrometry (TOF-MS) for analytical purposes is presented. The performance of TOF-MS combined with an inductively coupled plasma (ICP) ion source is discussed in detail. The advantages of TOF-MS detectors over the quadrupole mass filters for multi-elemental analysis of fast transient signals are discussed. The applications of ICP-TOF-MS for the detection of signals from laser ablation, electrothermal vaporization, gas and liquid chromatography, capillary electrophoresis and flow-injection analysis are reviewed. PMID:12880079

Balcerzak, Maria

2003-07-01

4

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

5

Comprehensive multidimensional separation methods by hyphenation of single-photon ionization time-of-flight mass spectrometry (SPI-TOF-MS) with GC and GCxGC.  

PubMed

One- and comprehensive two-dimensional gas chromatography were hyphenated with soft photoionization mass spectrometry. The characteristics of these two- and three-dimensional comprehensive separation techniques are discussed in detail. Using the innovative electron beam pumped excimer light source (EBEL) for single-photon ionization (SPI), organic molecules with ionization energies (E ( i )) of below 9.8 eV can be detected by a time-of-flight mass spectrometer (TOF-MS). SPI with 126 nm vacuum ultraviolet (VUV) photons enables the universal and soft ionization of organic molecules. SPI-TOF-MS hyphenated to one-dimensional gas chromatography results in a comprehensive two-dimensional separation method (GCxMS). To demonstrate this, diesel fuel was analyzed, and the resulting GCxMS chromatograms are discussed in depth. A three-dimensional separation method was also realized by combining comprehensive two-dimensional gas chromatography (GCxGC) with SPI-MS. In the resulting separation space, constituents originating from mineral oil diesel blended with biodiesel were dispersed along the two GC separation axes, while the molecular mass axis served as a third separation dimension. PMID:20669008

Eschner, Markus S; Welthagen, Werner; Gröger, Thomas M; Gonin, Marc; Fuhrer, Katrin; Zimmermann, Ralf

2010-10-01

6

Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics for comparison of caffeinated and decaffeinated coffee and its implications for Alzheimer's disease.  

PubMed

Findings from epidemiology, preclinical and clinical studies indicate that consumption of coffee could have beneficial effects against dementia and Alzheimer's disease (AD). The benefits appear to come from caffeinated coffee, but not decaffeinated coffee or pure caffeine itself. Therefore, the objective of this study was to use metabolomics approach to delineate the discriminant metabolites between caffeinated and decaffeinated coffee, which could have contributed to the observed therapeutic benefits. Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics approach was employed to characterize the metabolic differences between caffeinated and decaffeinated coffee. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed distinct separation between the two types of coffee (cumulative Q(2) = 0.998). A total of 69 discriminant metabolites were identified based on the OPLS-DA model, with 37 and 32 metabolites detected to be higher in caffeinated and decaffeinated coffee, respectively. These metabolites include several benzoate and cinnamate-derived phenolic compounds, organic acids, sugar, fatty acids, and amino acids. Our study successfully established GC-TOF-MS based metabolomics approach as a highly robust tool in discriminant analysis between caffeinated and decaffeinated coffee samples. Discriminant metabolites identified in this study are biologically relevant and provide valuable insights into therapeutic research of coffee against AD. Our data also hint at possible involvement of gut microbial metabolism to enhance therapeutic potential of coffee components, which represents an interesting area for future research. PMID:25098597

Chang, Kai Lun; Ho, Paul C

2014-01-01

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

2012-03-25

8

Rapid Identification of Bacillus anthracis Spores in Suspicious Powder Samples by Using Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS)  

PubMed Central

Rapid and reliable identification of Bacillus anthracis spores in suspicious powders is important to mitigate the safety risks and economic burdens associated with such incidents. The aim of this study was to develop and validate a rapid and reliable laboratory-based matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis method for identifying B. anthracis spores in suspicious powder samples. A reference library containing 22 different Bacillus sp. strains or hoax materials was constructed and coupled with a novel classification algorithm and standardized processing protocol for various powder samples. The method's limit of B. anthracis detection was determined to be 2.5 × 106 spores, equivalent to a 55-?g sample size of the crudest B. anthracis-containing powder discovered during the 2001 Amerithrax incidents. The end-to-end analysis method was able to successfully discriminate among samples containing B. anthracis spores, closely related Bacillus sp. spores, and commonly encountered hoax materials. No false-positive or -negative classifications of B. anthracis spores were observed, even when the analysis method was challenged with a wide range of other bacterial agents. The robustness of the method was demonstrated by analyzing samples (i) at an external facility using a different MALDI-TOF MS instrument, (ii) using an untrained operator, and (iii) using mixtures of Bacillus sp. spores and hoax materials. Taken together, the observed performance of the analysis method developed demonstrates its potential applicability as a rapid, specific, sensitive, robust, and cost-effective laboratory-based analysis tool for resolving incidents involving suspicious powders in less than 30 min. PMID:23811517

van der Laaken, Anton L.; Blatny, Janet Martha; Paauw, Armand

2013-01-01

9

Multi-residue analysis method for analysis of pharmaceuticals using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS) in water sample  

NASA Astrophysics Data System (ADS)

In this work, a developed method using solid - phase extraction (SPE) followed by liquid chromatography - time of flight mass spectrometry (LC-ESI-TOF/MS) was developed and validated for quantification and confirmation of eleven pharmaceuticals with different therapeutic classes in water samples, Malaysia. These compounds are caffeine (CAF), prazosin (PRZ), enalapril (ENL), carbamazepine (CBZ), nifedipine (NFD), levonorgestrel (LNG), simvastatin (SMV), hydrochlorothiazide (HYD), gliclazide (GLIC), diclofenac-Na (DIC-Na) and mefenamic acid (MEF). LC was performed on a Dionex Ultimate 3000/LC 09115047 (USA) system. Chromatography was performed on a Thermo Scientific C18 (250 mm × 2.1 mm, i.d.: 5?m) column. Several parameters were optimised such as; mobile phase, gradient elution, collision energy and solvent elution for extraction of compounds from water. The recoveries obtained ranged from 30-148 % in river water. Five pharmaceutical compounds were detected in the surface water samples: caffeine, prazosin, enalpril, diclofenac-Na and mefenamic acid. The developed method is precise and accepted recoveries were got. In addition, this method is suitable to identify and quantify trace concentrations of pharmaceuticals in surface water.

Al-Qaim, Fouad Fadhil; Abdullah, Md Pauzi; Othman, Mohamed Rozali

2013-11-01

10

Rapid and highly accurate detection of steryl glycosides by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS).  

PubMed

This study describes the development and validation of a fast, accurate, and precise UPLC-Q-TOF-MS method for the analysis of steryl glycosides (SGs). The best combination of separation and sensitivity was obtained with a methanol/water gradient and formic acid as additive, using electrospray ionization (ESI). SGs were detected almost exclusively as sodiated adducts, allowing identification of the intact molecule, including the sugar moiety. The TOF-MS system offered high mass accuracy (1.3 ppm), providing a valuable tool for SG identification. The method was used to quantify single SG species in oat bran and whole wheat, and it was demonstrated that reliable quantification requires accounting for the matrix effect, which may reduce the SG signal by up to 50% in some samples. The level of matrix effect also depends on food matrices with various SG contents, indicating that it should be individually considered for each sample. PMID:25175549

Oppliger, Selina R; Münger, Linda H; Nyström, Laura

2014-10-01

11

Rapid Discrimination of Haemophilus influenzae, H. parainfluenzae, and H. haemolyticus by Fluorescence In Situ Hybridization (FISH) and Two Matrix-Assisted Laser-Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) Platforms  

PubMed Central

Background Due to considerable differences in pathogenicity, Haemophilus influenzae, H. parainfluenzae and H. haemolyticus have to be reliably discriminated in routine diagnostics. Retrospective analyses suggest frequent misidentifications of commensal H. haemolyticus as H. influenzae. In a multi-center approach, we assessed the suitability of fluorescence in situ hybridization (FISH) and matrix-assisted laser-desorption-ionization time-of-flight mass-spectrometry (MALDI-TOF-MS) for the identification of H. influenzae, H. parainfluenzae and H. haemolyticus to species level. Methodology A strain collection of 84 Haemophilus spp. comprising 50 H. influenzae, 25 H. parainfluenzae, 7 H. haemolyticus, and 2 H. parahaemolyticus including 77 clinical isolates was analyzed by FISH with newly designed DNA probes, and two different MALDI-TOF-MS systems (Bruker, Shimadzu) with and without prior formic acid extraction. Principal Findings Among the 84 Haemophilus strains analyzed, FISH led to 71 correct results (85%), 13 uninterpretable results (15%), and no misidentifications. Shimadzu MALDI-TOF-MS resulted in 59 correct identifications (70%), 19 uninterpretable results (23%), and 6 misidentifications (7%), using colony material applied directly. Bruker MALDI-TOF-MS with prior formic acid extraction led to 74 correct results (88%), 4 uninterpretable results (5%) and 6 misidentifications (7%). The Bruker MALDI-TOF-MS misidentifications could be resolved by the addition of a suitable H. haemolyticus reference spectrum to the system's database. In conclusion, no analyzed diagnostic procedure was free of errors. Diagnostic results have to be interpreted carefully and alternative tests should be applied in case of ambiguous test results on isolates from seriously ill patients. PMID:23646201

Frickmann, Hagen; Christner, Martin; Donat, Martina; Berger, Anja; Essig, Andreas; Podbielski, Andreas; Hagen, Ralf Matthias; Poppert, Sven

2013-01-01

12

Optimization of experimental and modelling parameters for the differentiation of beverage spoiling yeasts by Matrix-Assisted-Laser-Desorption/Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) in response to varying growth conditions.  

PubMed

The growth of spoiling yeasts in beverages results in reduced quality, economic and image losses. Therefore, biochemical and DNA-based identification methods have been developed but are mostly time-consuming and laborious. Matrix-Assisted-Laser-Desorption/Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) could deliver discriminative peptide mass fingerprints within minutes and could thus be a rapid and reliable tool for identification and differentiation. However, routine analysis of yeasts by MALDI-TOF MS is yet impaired by low reproducibility and effects of different physiological states of organisms on the reliability of the identification method are still controversial. The aim of this study was to optimize sample preparation and measurement parameterization using three spoilage yeasts (Saccharomyces cerevisiae var. diastaticus, Wickerhamomyces anomalus and Debaryomyces hansenii). The influence of environmental or physiological parameters including oxygen availability, different nutrients, cell density and growth phase were analysed and revealed small differences in mass fingerprints. Yeasts grown in the presence or absence of oxygen were precisely differentiated along these differences in mass fingerprints and a crude classification of growth phase was possible. Cell concentration did not affect the spectra distinctly, neither qualitatively nor quantitatively, and an influence of available nutrients could not be measured in each case. However, core mass peaks remained constant under all tested conditions enabling reliable identification. PMID:24010620

Usbeck, Julia C; Kern, Carola C; Vogel, Rudi F; Behr, Jürgen

2013-12-01

13

Gas Chromatography Time-Of-Flight Mass Spectrometry (GC-TOF-MS)-Based Metabolomics for Comparison of Caffeinated and Decaffeinated Coffee and Its Implications for Alzheimer’s Disease  

PubMed Central

Findings from epidemiology, preclinical and clinical studies indicate that consumption of coffee could have beneficial effects against dementia and Alzheimer’s disease (AD). The benefits appear to come from caffeinated coffee, but not decaffeinated coffee or pure caffeine itself. Therefore, the objective of this study was to use metabolomics approach to delineate the discriminant metabolites between caffeinated and decaffeinated coffee, which could have contributed to the observed therapeutic benefits. Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics approach was employed to characterize the metabolic differences between caffeinated and decaffeinated coffee. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed distinct separation between the two types of coffee (cumulative Q2?=?0.998). A total of 69 discriminant metabolites were identified based on the OPLS-DA model, with 37 and 32 metabolites detected to be higher in caffeinated and decaffeinated coffee, respectively. These metabolites include several benzoate and cinnamate-derived phenolic compounds, organic acids, sugar, fatty acids, and amino acids. Our study successfully established GC-TOF-MS based metabolomics approach as a highly robust tool in discriminant analysis between caffeinated and decaffeinated coffee samples. Discriminant metabolites identified in this study are biologically relevant and provide valuable insights into therapeutic research of coffee against AD. Our data also hint at possible involvement of gut microbial metabolism to enhance therapeutic potential of coffee components, which represents an interesting area for future research. PMID:25098597

Chang, Kai Lun; Ho, Paul C.

2014-01-01

14

Source-Identifying Biomarker Ions between Environmental and Clinical Burkholderia pseudomallei Using Whole-Cell Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS)  

PubMed Central

Burkholderia pseudomallei is the causative agent of melioidosis, which is an endemic disease in Northeast Thailand and Northern Australia. Environmental reservoirs, including wet soils and muddy water, serve as the major sources for contributing bacterial infection to both humans and animals. The whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (whole-cell MALDI-TOF MS) has recently been applied as a rapid, accurate, and high-throughput tool for clinical diagnosis and microbiological research. In this present study, we employed a whole-cell MALDI-TOF MS approach for assessing its potency in clustering a total of 11 different B. pseudomallei isolates (consisting of 5 environmental and 6 clinical isolates) with respect to their origins and to further investigate the source-identifying biomarker ions belonging to each bacterial group. The cluster analysis demonstrated that six out of eleven isolates were grouped correctly to their sources. Our results revealed a total of ten source-identifying biomarker ions, which exhibited statistically significant differences in peak intensity between average environmental and clinical mass spectra using ClinProTools software. Six out of ten mass ions were assigned as environmental-identifying biomarker ions (EIBIs), including, m/z 4,056, 4,214, 5,814, 7,545, 7,895, and 8,112, whereas the remaining four mass ions were defined as clinical-identifying biomarker ions (CIBIs) consisting of m/z 3,658, 6,322, 7,035, and 7,984. Hence, our findings represented, for the first time, the source-specific biomarkers of environmental and clinical B. pseudomallei. PMID:24914956

Srisanga, Kitima; Roytrakul, Sittiruk; Tungpradabkul, Sumalee

2014-01-01

15

Fecal metabonomic study of a polysaccharide, MDG-1 from Ophiopogon japonicus on diabetic mice based on gas chromatography/time-of-flight mass spectrometry (GC TOF/MS).  

PubMed

Type 2 Diabetes Mellitus (T2DM) is a chronic metabolic disorder with systemic complications and has been a worldwide epidemic. Ophiopogon japonicus is a traditional Chinese medicine used to treat diabetes for thousands of years. From our previous work, we know that MDG-1, a water-soluble ?-D-fructan polysaccharide from O. japonicas could treat T2DM experimentally. However, MDG-1 is poorly absorbed and its mechanism of action is still unknown. Therefore, a GC TOF/MS-based metabonomic approach in combination with multivariate statistical analysis was performed to investigate the mechanism of MDG-1 in a spontaneous diabetic model. Female diabetic KKay mice (21 weeks old) were randomly divided into a diabetic group (n = 6, gavaged with distilled water) and a MDG-1-Diabetic group (n = 7, gavaged with MDG-1, 300 mg kg(-1)) and female C57BL/6 mice (21 weeks old) were set as controls (n = 6, gavaged with distilled water). After 8-weeks of treatment, feces samples were collected for GC-TOF/MS analysis. Consequently, 12 potential biomarkers were identified, including monosugars (D-tagatose, D-lyxose, D-erythrose, xylo-hexos-5-ulose, 2-deoxy-galactose), butanedioic acid, amino acids (phenylalanine, L-lysine, L-methionine, L-aspartic acid) and purine derivatives (7H-purine, 2'-deoxyinosine). We assume the monosugars and butanedioic acid were the fermentation products of MDG-1 by intestinal microbes and MDG-1 actions against diabetes might be accomplished through the absorbable monosugars and butanedioic acid via suppressing intestinal glucose absorption, enhancing liver glycogenesis, inhibiting glycogenolysis and promoting GLP-1 secretion. Besides, MDG-1 might alleviate diabetes and diabetic nephropathy by reducing 7H-purine and 2'-deoxyinosine. Further omics-driven studies including genomics, proteomics and metabonomics were considered to be carried out to provide direct evidence of gut microbiome contribution to MDG-1 actions. PMID:24292023

Zhu, Yunyun; Cong, Wenjuan; Shen, Lan; Wei, Hai; Wang, Yuan; Wang, Lingyi; Ruan, Kefeng; Wu, Fei; Feng, Yi

2014-02-01

16

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS)-based identification of pathogens from positive blood culture bottles.  

PubMed

Since the expansion of commercial use of MALDI-TOF/MS instruments for the identification of bacteria from culture which has occurred over the past 5-8 years, techniques for the identification of bacteria directly from positive blood cultures have been developed (Lagace-Wiens et al., J Clin Microbiol 50:3324-3328, 2012; Martiny et al., Eur J Clin Microbiol Infect Dis 31:2269-2281, 2012; Moussaoui et al., Clin Microbiol Infect 16:1631-1638, 2010). These techniques have the potential to provide definitive identification of pathogens causing sepsis 18-48 h earlier than conventional methodologies, and implementation of these methods has been shown to impact morbidity and hospital costs in a positive way (Martiny et al., Clin Microbiol Infect 19:E568-E581, 2013; Loonen et al., Eur J Clin Microbiol Infect Dis 31:1575-1583, 2012). Although many methods for purification of bacterial cells have been developed, including differential centrifugation, centrifuge lysis, and preincubation on sold media (March-Rossello et al., Eur J Clin Microbiol Infect Dis 32:699-704, 2013; Saffert et al., Diagn Microbiol Infect Dis 73:21-26, 2012; Schubert et al., J Mol Diagn 13:701-706, 2011), we will describe the method by which intact bacterial cells are extracted from positive blood culture bottles using a commercially available kit (SepsiTyper™) which is based on the centrifuge lysis methodology (Lagace-Wiens et al., J Clin Microbiol 50:3324-3328, 2012; Buchan et al., J Clin Microbiol 50:346-352, 2012). PMID:25319778

Lagacé-Wiens, Philippe

2015-01-01

17

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.  

PubMed

Toxic organophosphorus compounds (OPC), e.g., pesticides and nerve agents (NA), are known to phosphylate distinct endogenous proteins in vivo and in vitro. OPC adducts of butyrylcholinesterase and albumin are considered to be valuable biomarkers for retrospective verification of OPC exposure. Therefore, we have detected and identified novel adducts of human serum albumin (HSA) by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Pure albumin and plasma were incubated with numerous pesticides and NA of the V- and G-type in different molar ratios. Samples were prepared either by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by in-gel enzymatic cleavage using endoproteinase Glu-C (Glu-C) or by combining highly albumin-selective affinity extraction with ultrafiltration followed by reduction, carbamidomethylation, and enzymatic cleavage (Glu-C) prior to MALDI-TOF MS analysis. Characteristic mass shifts for phosphylation revealed tyrosine adducts at Y(411) (Y(401)KFQNALLVRY(411)TKKVPQVSTPTLVE(425)), Y(148) and Y(150) (I(142)ARRHPY(148)FY(150)APE(153), single and double labeled), and Y(161) (L(154)LFFAKRY(161)KAAFTE(167)) produced by original NA (tabun, sarin, soman, cyclosarin, VX, Chinese VX, and Russian VX) as well as by chlorpyrifos-oxon, diisopropyl fluorophosphate (DFP), paraoxon-ethyl (POE), and profenofos. MALDI-MS/MS of the single-labeled I(142)-E(153) peptide demonstrated that Y(150) was phosphylated with preference to Y(148). Aged albumin adducts were not detected. The procedure described was reproducible and feasible for detection of adducts at the most reactive Y(411)-residue (S/N???3) when at least 1% of total albumin was labeled. This was achieved by incubating plasma with molar HSA/OPC ratios ranging from approximately 1:0.03 (all G-type NA, DFP, and POE) to 1:3 (V-type NA, profenofos). Relative signal intensity of the Y(411) adduct correlated well with the spotted relative molar amount underlining the usefulness for quantitative adduct determination. In conclusion, the current analytical design exhibits potential as a verification tool for high-dose exposure. PMID:20730528

John, Harald; Breyer, Felicitas; Thumfart, Jörg Oliver; Höchstetter, Hans; Thiermann, Horst

2010-11-01

18

Investigation of the volatile composition of pinotage wines fermented with different malolactic starter cultures using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOF-MS).  

PubMed

Headspace solid phase microextraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (HS-SPME-GC × GC-TOF-MS) was used for the detailed investigation of the impact of malolactic fermentation (MLF) using three commercial Oenococcus oeni strains on the volatile composition of Vitis vinifera cv. Pinotage wines. GC × GC allowed the identification of 115 volatile compounds, including both major constituents and trace-level compounds, in a single analysis. A number of compounds differing in mean concentration levels between the control wines and those fermented with different starter cultures were shown for the first time to be influenced by MLF and/or the bacterial strain. Principal component analysis (PCA) provided excellent separation between the wines fermented with different MLF starter cultures and the control wine. Significantly different levels for some volatile compounds in wines fermented with one of the LAB starter cultures could be indicative of metabolic differences of this strain. PMID:22023396

Vestner, Jochen; Malherbe, Sulette; Du Toit, Maret; Nieuwoudt, Hélène H; Mostafa, Ahmed; Górecki, Tadeusz; Tredoux, Andreas G J; de Villiers, André

2011-12-28

19

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

20

A Silicon Nanomembrane Detector for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) of Large Proteins  

PubMed Central

We describe a MALDI-TOF ion detector based on freestanding silicon nanomembrane technology. The detector is tested in a commercial MALDI-TOF mass spectrometer with equimolar mixtures of proteins. The operating principle of the nanomembrane detector is based on phonon-assisted field emission from these silicon nanomembranes, in which impinging ion packets excite electrons in the nanomembrane to higher energy states. Thereby the electrons can overcome the vacuum barrier and escape from the surface of the nanomembrane via field emission. Ion detection is demonstrated of apomyoglobin (16,952 Da), aldolase (39,212 Da), bovine serum albumin (66,430 Da), and their equimolar mixtures. In addition to the three intact ions, a large number of fragment ions are also revealed by the silicon nanomembrane detector, which are not observable with conventional detectors. PMID:24152929

Park, Jonghoo; Blick, Robert H.

2013-01-01

21

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

NASA Astrophysics Data System (ADS)

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 the low mass resolution of the quadrupoles used this has the disadvantage that identification of trace gases under study is not unambiguous. Here we report the development of a new version of PTR-MS instruments using a time-of-flight mass spectrometer, which is capable of measuring VOCs at ultra-low concentrations (as low as a few pptv) under high mass resolution (as high as 6000 m/[Delta]m in the V-mode) with a mass range of beyond 100 000 amu. This instrument was constructed by interfacing the well characterized and recently improved Ionicon hollow cathode ion source and drift tube section with a Tofwerk orthogonal acceleration reflectron time-of-flight mass spectrometer. We will first discuss the set-up of this new PTR-TOF-MS mass spectrometer instrument, its performance (with a sensitivity of several tens of cps/ppbv) and finally give some examples concerning urban air measurements where sensitivity, detection limit and mass resolution is essential to obtain relevant data.

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

2009-09-01

22

Analysis of Wheat Prolamins, the Causative Agents of Celiac Sprue, Using Reversed Phase High Performance Liquid Chromatography (RP-HPLC) and Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS)  

PubMed Central

Wheat prolamins, commonly known as “gluten”, are a complex mixture of 71–78 proteins, which constitute ~80% of the proteins in the wheat grains and supply 50% of the global dietary protein demand. Prolamins are also responsible for numerous gluten-induced disorders and determine the unique visco-elastic properties of the wheat dough. These properties necessitate the reliable determination of the prolamin composition in wheat grains and their derived products. Therefore, this study examined the impact of HPLC conditions, including column type, column temperature, flow rate, and the gradient of polar and non-polar solvents in the mobile phase, to improve the analytical resolution of prolamins. The following conditions were found optimal for analyses: column temperature 60 °C, flow rate 1.0 mL/min and an elution gradient of 20%–60% of 0.1% trifluoroacetic acid + acetonitrile in 60 min. For further improvement of resolution, gliadin and glutenin extracts were analyzed using MALDI-TOF-MS in combination with HPLC fractionation. Two semi-quantitative methods, densitometry of stained polyacrylamide gels and HPLC, were used to determine relative prolamin quantities and the correspondence between the methods was established. The combinatorial gluten analyses approach developed during the present study was used to analyze prolamin profiles of wheat transformants expressing DEMETER silencing artificial microRNA, and the results are discussed. PMID:24739977

Mejías, Jaime H.; Lu, Xiaoqiao; Osorio, Claudia; Ullman, Jeffrey L.; von Wettstein, Diter; Rustgi, Sachin

2014-01-01

23

Analysis of wheat prolamins, the causative agents of celiac sprue, using reversed phase high performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).  

PubMed

Wheat prolamins, commonly known as "gluten", are a complex mixture of 71-78 proteins, which constitute ~80% of the proteins in the wheat grains and supply 50% of the global dietary protein demand. Prolamins are also responsible for numerous gluten-induced disorders and determine the unique visco-elastic properties of the wheat dough. These properties necessitate the reliable determination of the prolamin composition in wheat grains and their derived products. Therefore, this study examined the impact of HPLC conditions, including column type, column temperature, flow rate, and the gradient of polar and non-polar solvents in the mobile phase, to improve the analytical resolution of prolamins. The following conditions were found optimal for analyses: column temperature 60 °C, flow rate 1.0 mL/min and an elution gradient of 20%-60% of 0.1% trifluoroacetic acid + acetonitrile in 60 min. For further improvement of resolution, gliadin and glutenin extracts were analyzed using MALDI-TOF-MS in combination with HPLC fractionation. Two semi-quantitative methods, densitometry of stained polyacrylamide gels and HPLC, were used to determine relative prolamin quantities and the correspondence between the methods was established. The combinatorial gluten analyses approach developed during the present study was used to analyze prolamin profiles of wheat transformants expressing DEMETER silencing artificial microRNA, and the results are discussed. PMID:24739977

Mejías, Jaime H; Lu, Xiaoqiao; Osorio, Claudia; Ullman, Jeffrey L; von Wettstein, Diter; Rustgi, Sachin

2014-04-01

24

Metabolomic Analysis Using Ultra-Performance Liquid Chromatography-Quadrupole-Time of Flight Mass Spectrometry (UPLC-Q-TOF MS) Uncovers the Effects of Light Intensity and Temperature under Shading Treatments on the Metabolites in Tea  

PubMed Central

To investigate the effect of light intensity and temperature on the biosynthesis and accumulation of quality-related metabolites, field grown tea plants were shaded by Black Net and Nano-insulating Film (with additional 2–4°C cooling effect) with un-shaded plants as a control. Young shoots were subjected to UPLC-Q-TOF MS followed by multivariate statistical analysis. Most flavonoid metabolites (mainly flavan-3-ols, flavonols and their glycosides) decreased significantly in the shading treatments, while the contents of chlorophyll, ?-carotene, neoxanthin and free amino acids, caffeine, benzoic acid derivatives and phenylpropanoids increased. Comparison between two shading treatments indicated that the lower temperature under Nano shading decreased flavonols and their glycosides but increased accumulation of flavan-3-ols and proanthocyanidins. The comparison also showed a greater effect of temperature on galloylation of catechins than light intensity. Taken together, there might be competition for substrates between the up- and down-stream branches of the phenylpropanoid/flavonoid pathway, which was influenced by light intensity and temperature. PMID:25390340

Ma, Lifeng; Yi, Xiaoyun; Ruan, Jianyun

2014-01-01

25

Profile of phenolic compounds of Brazilian virgin olive oils by rapid resolution liquid chromatography coupled to electrospray ionisation time-of-flight mass spectrometry (RRLC-ESI-TOF-MS).  

PubMed

In recent years, agronomical researchers began to cultivate several olive varieties in different regions of Brazil to produce virgin olive oil (VOO). Because there has been no reported data regarding the phenolic profile of the first Brazilian VOO, the aim of this work was to determine phenolic contents of these samples using rapid-resolution liquid chromatography coupled to electrospray ionisation time-of-flight mass spectrometry. 25 VOO samples from Arbequina, Koroneiki, Arbosana, Grappolo, Manzanilla, Coratina, Frantoio and MGS Mariense varieties from three different Brazilian states and two crops were analysed. It was possible to quantify 19 phenolic compounds belonging to different classes. The results indicated that Brazilian VOOs have high total phenolic content because the values were comparable with those from high-quality VOOs produced in other countries. VOOs from Coratina, Arbosana and Grappolo presented the highest total phenolic content. These data will be useful in the development and improvement of Brazilian VOO. PMID:25306359

Ballus, Cristiano Augusto; Quirantes-Piné, Rosa; Bakhouche, Abdelhakim; da Silva, Luiz Fernando de Oliveira; de Oliveira, Adelson Francisco; Coutinho, Enilton Fick; da Croce, Dorli Mario; Segura-Carretero, Antonio; Godoy, Helena Teixeira

2015-03-01

26

Quantitation using GC-TOF-MS: example of bromazepam.  

PubMed

Time-of-flight mass spectrometry (TOF-MS) offers new perspectives for forensic toxicology. Qualitative and quantitative analyses of a mixture of three selected benzodiazepines (diazepam, nordazepam and bromazepam) were used to compare gas chromatography (GC-TOF-MS, quadrupole GC-MS, GC-ECD) and liquid chromatography (HPLC-DAD) data. Method validation parameters like LOD, LOQ, S/N-ratios reflect the capabilities of GC-TOF-MS. Five-point calibrations for bromazepam in human peripheral blood (50, 100, 160, 200, 300 ng/ml) using medazepam as internal standard (1000 ng/ml) were performed. The calibrations using GC-TOF-MS (using the fragments of m/z 236 and 288), GC-ECD (dual system) and HPLC-DAD (at 235 nm) all showed correlation coefficients close or superior to 0.99. Quadrupole GC-MS data was not used in the comparison of extracted samples due to the low sensitivity in the full scan mode. Two analyses of real cases concerning bromazepam are presented. In the first case, the presence or absence of bromazepam could not be established with both HPLC-DAD and GC-ECD due to background signals. The extracted ion chromatograms and spectrum traces after the analysis with the GC-TOF-MS could clearly excluded the presence of bromazepam. The second case illustrates the quantitation of bromazepam, where both HPLC-DAD and GC-ECD were unable to give satisfactory results, again due to interfering background signals. The analyses performed on the GC-TOF-MS-system demonstrated high sensitivity and also high selectivity due to the high quality of mass spectra obtained. The advantages of GC-TOF-MS make it a promising analytical technique for forensic toxicology. PMID:12208027

Aebi, B; Sturny-Jungo, R; Bernhard, W; Blanke, R; Hirsch, R

2002-08-14

27

[Discrimination of plasticizers and screening of phthalates in polyvinyl chloride using DART-TOF/MS].  

PubMed

A technique using a direct analysis in real time (DART) ion source coupled with time of flight/mass spectrometry (TOF/MS) was developed to discriminate plasticizers and to screen phthalates in polyvinyl chloride (PVC). In DART-TOF/MS analysis of 40 plasticizers, the protonated molecular ion, [M+H](+), was detected for most plasticizers, and the molecular weight could be easily predicted. In the analysis of PVC sheets and toys, mass spectra of plasticizers were successfully detected, and accordingly, plasticizers in PVC were easily discriminated. PVC with a phthalates content in excess of 0.1% could be screened accurately according to the DART-TOF/MS ion intensity of phthalates corresponding to the limit of detection or a suitable criterion value. DART-TOF/MS analysis is a simple and rapid technique that is suitable for the discrimination of plasticizers and for screening of phthalates in PVC. PMID:20827052

Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Hirahara, Yoshichika; Kawamura, Maiko; Kikura-Hanajiri, Ruri; Goda, Yukihiro; Kawamura, Yoko

2010-01-01

28

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

29

Identification of Dermatophyte Species after Implementation of the In-House MALDI-TOF MS Database  

PubMed Central

Despite that matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has become a powerful tool in the clinical microbiology setting, few studies have till now focused on MALDI-TOF MS-based identification of dermatophytes. In this study, we analyze dermatophytes strains isolated from clinical samples by MALDI-TOF MS to supplement the reference database available in our laboratory. Twenty four dermatophytes (13 reference strains and 11 field isolated strains), identified by both conventional and molecular standard procedures, were analyzed by MALDI-TOF MS, and the spectra obtained were used to supplement the available database, limited to a few species. To verify the robustness of the implemented database, 64 clinical isolates other than those used for the implementation were identified by MALDI-TOF MS. The implementation allowed the identification of the species not included in the original database, reinforced the identification of the species already present and correctly identified those within the Trichophyton mentagrophytes complex previously classified as Trichophyton. tonsurans by MALDI-TOF MS. The dendrogram obtained by analyzing the proteic profiles of the different species of dermatophytes reflected their taxonomy, showing moreover, in some cases, a different clusterization between the spectra already present in the database and those newly added. In this study, MALDI-TOF MS proved to be a useful tool suitable for the identification of dermatophytes for diagnostic purpose. PMID:25216335

Calderaro, Adriana; Motta, Federica; Montecchini, Sara; Gorrini, Chiara; Piccolo, Giovanna; Piergianni, Maddalena; Buttrini, Mirko; Medici, Maria Cristina; Arcangeletti, Maria Cristina; Chezzi, Carlo; De Conto, Flora

2014-01-01

30

Performance of mass spectrometric identification of bacteria and yeasts routinely isolated in a clinical microbiology laboratory using MALDI-TOF MS  

PubMed Central

Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is an emerging technology newly applied to identifying bacterial and yeast strains. The aim of this study was to evaluate the clinical performance of the VITEK® MS system in the identification of bacteria and yeast strains routinely isolated from clinical samples. Methods We prospectively analyzed routine MALDI-TOF mass spectrometry identification in parallel with conventional phenotypic identification of bacteria and yeasts regardless of phylum or source of isolation. Discordant results were resolved with 16S rDNA or internal transcribed spacer (ITS) gene sequencing. Colonies (a single deposit on a MALDI disposable target without any prior extraction step) were analyzed using the VITEK® MS system. Peptide spectra acquired by the system were compared with the VITEK® MS IVD database Version 2.0, and the identification scores were recorded. Results Of the 1,181 isolates (1,061 bacterial isolates and 120 yeast isolates) analyzed, 99.5% were correctly identified by MALDI-TOF mass spectrometry; 95.7% identified to the species level, 3.6% identified to the genus level, and 0.3% identified within a range of species belonging to different genera. Conversely, 0.1% of isolates were misidentified and 0.4% were unidentified, partly because the species were not included in the database. Re-testing using a second deposit provided a successful identification for 0.5% of isolates unidentified with the first deposit. Our results show that the VITEK® MS system has exceptional performance in identifying bacteria and yeast by comparing acquired peptide spectra to those contained in its database. Conclusions MALDI-TOF mass spectrometry is a rapid, accurate, and relatively inexpensive method for bacterial and yeast identification. Our results demonstrate that the VITEK® MS system is a fast and reliable technique, and has the potential to replace conventional phenotypic identification for most bacterial and yeast strains routinely isolated in clinical microbiology laboratories. PMID:24822114

Wang, Weiping; Xi, Haiyan; Huang, Mei; Wang, Jie; Fan, Ming; Chen, Yong; Shao, Haifeng

2014-01-01

31

Wine yeast typing by MALDI-TOF MS.  

PubMed

For the production of wine, the most important industrially used yeast species is Saccharomyces cerevisiae. Years of experience have shown that wine quality and property are significantly affected by the employed strain conducting the fermentation. Consequently, the ability of a strain level differentiation became an important requirement of modern winemaking. In our study, we showed that the differentiation by time-consuming and laborious biochemical and DNA-based methods to enable a constant beverage quality and characteristics can be replaced by matrix-assisted-laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), accompanied by the additional benefit of an application prediction. Mass fingerprints of 33 Saccharomyces strains, which are commonly used for varying wine fermentations, were generated by MALDI-TOF MS upon optimized sample preparation and instrument settings and analyzed by a cluster analysis for strain or ecotype-level differentiation. As a reference method, delta-PCR was chosen to study the genetic diversity of the employed strains. Finally, the cluster analyses of both methods were compared. It could be shown that MALDI-TOF MS, acting at proteome level, provides valuable information about the relationship between yeast strains and their application potential according to their MALDI mass fingerprint. PMID:24615383

Usbeck, Julia C; Wilde, Caroline; Bertrand, Dave; Behr, Jürgen; Vogel, Rudi F

2014-04-01

32

A critical assessment of SELDI-TOF-MS for biomarker discovery in serum and tissue of patients with an ovarian mass  

PubMed Central

Background Less than 25% of patients with a pelvic mass who are presented to a gynecologist will eventually be diagnosed with epithelial ovarian cancer. Since there is no reliable test to differentiate between different ovarian tumors, accurate classification could facilitate adequate referral to a gynecological oncologist, improving survival. The goal of our study was to assess the potential value of a SELDI-TOF-MS based classifier for discriminating between patients with a pelvic mass. Methods Our study design included a well-defined patient population, stringent protocols and an independent validation cohort. We compared serum samples of 53 ovarian cancer patients, 18 patients with tumors of low malignant potential, and 57 patients with a benign ovarian tumor on different ProteinChip arrays. In addition, from a subset of 84 patients, tumor tissues were collected and microdissection was used to isolate a pure and homogenous cell population. Results Diagonal Linear Discriminant Analysis (DLDA) and Support Vector Machine (SVM) classification on serum samples comparing cancer versus benign tumors, yielded models with a classification accuracy of 71-81% (cross-validation), and 73-81% on the independent validation set. Cancer and benign tissues could be classified with 95-99% accuracy using cross-validation. Tumors of low malignant potential showed protein expression patterns different from both benign and cancer tissues. Remarkably, none of the peaks differentially expressed in serum samples were found to be differentially expressed in the tissue lysates of those same groups. Conclusion Although SELDI-TOF-MS can produce reliable classification results in serum samples of ovarian cancer patients, it will not be applicable in routine patient care. On the other hand, protein profiling of microdissected tumor tissue may lead to a better understanding of oncogenesis and could still be a source of new serum biomarkers leading to novel methods for differentiating between different histological subtypes. PMID:22824475

2012-01-01

33

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

34

[Identification of staphylococci directly from positive blood culture bottles by MALDI-TOF MS system].  

PubMed

Bloodstream infections are substantial causes of morbidity and mortality worldwide. Staphylococcus species are the most commonly isolated microorganisms from blood cultures in clinical microbiology laboratories. MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time- of- Flight Mass Spectrometry) system allows the identification of microorganisms directly from positive blood culture bottles. The aim of this study was to evaluate the MALDI-TOF MS system for the identification of staphylococci directly from the positive blood culture bottles which revealed the presence of gram-positive cocci by staining. A total of 96 positive blood culture bottles that yielded gram-positive cocci by Gram stain were evaluated. These blood cultures were obtained from 69 patients between December 2013-February 2014. Conventional methods and BD Phoenix™ automated bacterial identification system (Becton Dickinson, USA) were used for routine identification. The strains were also identified by real-time Taqman PCR (qPCR) which was considered as the reference method. In MALDI-TOF MS method, MALDI Sepsityper™ Kit was used for the bacterial identification and all measurements were carried out by using Microflex LT instrument and FlexControl 3.0 software (Bruker Daltonics, USA). Of 96 culture bottles positive for gram-positive cocci, 90 were correctly identified as staphylococci at genus level with all the three study methods (qPCR, BD Phoenix, Bruker MALDI-TOF MS). The other six samples were identified as Enterococcus faecium (n= 4) and Streptococcus pyogenes (n= 2) by both Phoenix and the MALDI-TOF systems. Of the 90 samples, 87 were identified at the species level (15 S.aureus, 33 S.epidermidis, 29 S.hominis, 10 S.haemolyticus) and three at the genus level by the reference qPCR method. When comparing the results obtained by qPCR and Bruker MALDI-TOF MS, incompatibility was detected for three isolates. Those isolates were identified as S.hominis by qPCR, however two of them were identified as S.haemolyticus and one as S.epidermidis by MALDI-TOF MS. Compared with real-time Taqman PCR it was detected that Bruker MALDI TOF MS was identified 100% of S.aureus to the genus and species level and 100% and 96.6% of coagulase-negative staphylococci (CNS) to the genus and species level, respectively. In conclusion, it was thought that Bruker MALDI TOF MS system may allow rapid and reliable identification of S.aureus and CNS directly from positive blood culture bottles compared with the routine methods used in the clinical microbiology laboratory. PMID:25052104

Kilic, Abdullah; Baysallar, Mehmet

2014-07-01

35

Detection of Rickettsia spp in Ticks by MALDI-TOF MS  

PubMed Central

Background Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has been shown to be an effective tool for the rapid identification of arthropods, including tick vectors of human diseases. Methodology/Principal Findings The objective of the present study was to evaluate the use of MALDI-TOF MS to identify tick species, and to determine the presence of rickettsia pathogens in the infected Ticks. Rhipicephalus sanguineus and Dermacentor marginatus Ticks infected or not by R. conorii conorii or R. slovaca, respectively, were used as experimental models. The MS profiles generated from protein extracts prepared from tick legs exhibited mass peaks that distinguished the infected and uninfected Ticks, and successfully discriminated the Rickettsia spp. A blind test was performed using Ticks that were laboratory-reared, collected in the field or removed from patients and infected or not by Rickettsia spp. A query against our in-lab arthropod MS reference database revealed that the species and infection status of all Ticks were correctly identified at the species and infection status levels. Conclusions/Significance Taken together, the present work demonstrates the utility of MALDI-TOF MS for a dual identification of tick species and intracellular bacteria. Therefore, MALDI-TOF MS is a relevant tool for the accurate detection of Rickettsia spp in Ticks for both field monitoring and entomological diagnosis. The present work offers new perspectives for the monitoring of other vector borne diseases that present public health concerns. PMID:25659152

Yssouf, Amina; Almeras, Lionel; Terras, Jérôme; Socolovschi, Cristina; Raoult, Didier; Parola, Philippe

2015-01-01

36

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. PMID:23457514

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

2013-01-01

37

Rapid identification of oral Actinomyces species cultivated from subgingival biofilm by MALDI-TOF-MS  

PubMed Central

Background Actinomyces are a common part of the residential flora of the human intestinal tract, genitourinary system and skin. Isolation and identification of Actinomyces by conventional methods is often difficult and time consuming. In recent years, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has become a rapid and simple method to identify bacteria. Objective The present study evaluated a new in-house algorithm using MALDI-TOF-MS for rapid identification of different species of oral Actinomyces cultivated from subgingival biofilm. Design Eleven reference strains and 674 clinical strains were used in this study. All the strains were preliminarily identified using biochemical methods and then subjected to MALDI-TOF-MS analysis using both similarity-based analysis and classification methods (support vector machine [SVM]). The genotype of the reference strains and of 232 clinical strains was identified by sequence analysis of the 16S ribosomal RNA (rRNA). Results The sequence analysis of the 16S rRNA gene of all references strains confirmed their previous identification. The MALDI-TOF-MS spectra obtained from the reference strains and the other clinical strains undoubtedly identified as Actinomyces by 16S rRNA sequencing were used to create the mass spectra reference database. Already a visual inspection of the mass spectra of different species reveals both similarities and differences. However, the differences between them are not large enough to allow a reliable differentiation by similarity analysis. Therefore, classification methods were applied as an alternative approach for differentiation and identification of Actinomyces at the species level. A cross-validation of the reference database representing 14 Actinomyces species yielded correct results for all species which were represented by more than two strains in the database. Conclusions Our results suggest that a combination of MALDI-TOF-MS with powerful classification algorithms, such as SVMs, provide a useful tool for the differentiation and identification of oral Actinomyces. PMID:25597306

Stingu, Catalina S.; Borgmann, Toralf; Rodloff, Arne C.; Vielkind, Paul; Jentsch, Holger; Schellenberger, Wolfgang; Eschrich, Klaus

2015-01-01

38

Determination of photoionization cross-sections of different organic molecules using gas chromatography coupled to single-photon ionization (SPI) time-of-flight mass spectrometry (TOF-MS) with an electron-beam-pumped rare gas excimer light source (EBEL): influence of molecular structure and analytical implications.  

PubMed

This work describes a fast and reliable method for determination of photoionization cross-sections (PICS) by means of gas chromatography (GC) coupled to single-photon ionization mass spectrometry (SPI-MS). Photoionization efficiency (PIE) data for 69 substances was obtained at a photon energy of 9.8 ± 0.4 eV using an innovative electron-beam-pumped rare gas excimer light source (EBEL) filled with argon. The investigated analytes comprise 12 alkylbenzenes as well as 11 other substituted benzenes, 23 n-alkanes, ten polyaromatic hydrocarbons, seven aromatic heterocycles, and six polyaromatic heterocycles. Absolute PICS for each substance at 9.8 eV are calculated from the relative photoionization efficiencies of the compounds with respect to benzene, whose photoionization cross-section data is well known. Furthermore, a direct correlation between the type of benzene substituents and their absolute PICS is presented and discussed in depth. Finally, comparison of previously measured photoionization cross-sections for 20 substances shows good agreement with the data of the present work. PMID:21740643

Eschner, Markus S; Zimmermann, Ralf

2011-07-01

39

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. PMID:22192890

2011-01-01

40

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

41

Performance of two resin-containing blood culture media in detection of bloodstream infections and in direct matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) broth assays for isolate identification: clinical comparison of the BacT/Alert Plus and Bactec Plus systems.  

PubMed

We compared the clinical performances of the BacT/Alert Plus (bioMérieux) and Bactec Plus (Becton Dickinson) aerobic and anaerobic blood culture (BC) media with adsorbent polymeric beads. Patients ? 16 years old with suspected bloodstream infections (BSIs) were enrolled in intensive care units and infectious disease wards. A single 40-ml blood sample was collected from each and used to inoculate (10 ml/bottle) one set of BacT/Alert Plus cultures and one set of Bactec Plus cultures, each set consisting of one aerobic and one anaerobic bottle. Cultures were incubated ? 5 days in the BacT/Alert 3D and Bactec FX instruments, respectively. A total of 128 unique BSI episodes were identified based on the recovery of clinically significant growth in 212 aerobic cultures (106 BacT/Alert and 106 Bactec) and 151 anaerobic cultures (82 BacT/Alert and 69 Bactec). The BacT/Alert aerobic medium had higher recovery rates for Gram-positive cocci (P = 0.024), whereas the Bactec aerobic medium was superior for recovery of Gram-negative bacilli (P = 0.006). BacT/Alert anaerobic medium recovery rates exceeded those of the Bactec anaerobic medium for total organisms (P = 0.003), Gram-positive cocci (P = 0.013), and Escherichia coli (P = 0.030). In terms of capacity for diagnosing the 128 septic episodes, the BacT/Alert and Bactec sets were comparable, although the former sets diagnosed more BSIs caused by Gram-positive cocci (P = 0.008). They also allowed earlier identification of coagulase-negative staphylococcal growth (mean, 2.8 h; P = 0.003) and growth in samples from patients not on antimicrobial therapy that yielded positive results (mean, 1.3 h; P < 0.001). Similarly high percentages of microorganisms in BacT/Alert and Bactec cultures (93.8% and 93.3%, respectively) were identified by direct matrix-assisted laser desorption ionization-time of flight mass spectrometry assay of BC broths. The BacT/Alert Plus media line appears to be a reliable, timesaving tool for routine detection of BSIs in the population we studied, although further studies are needed to evaluate their performance in other settings. PMID:25031441

Fiori, Barbara; D'Inzeo, Tiziana; Di Florio, Viviana; De Maio, Flavio; De Angelis, Giulia; Giaquinto, Alessia; Campana, Lara; Tanzarella, Eloisa; Tumbarello, Mario; Antonelli, Massimo; Sanguinetti, Maurizio; Spanu, Teresa

2014-10-01

42

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

43

Serum biomarker screening for the diagnosis of early gastric cancer using SELDI-TOF-MS.  

PubMed

In this study, we performed a proteomic analysis of sera from stage I gastric cancer patients using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) and established a diagnostic model for the early diagnosis of stage I gastric cancer. Serum samples from 169 gastric cancer patients and 83 age- and gender-matched healthy individuals were analyzed by SELDI-TOF-MS ProteinChip array technology. The SELDI-TOF-MS spectral data were analyzed using the Biomarker Wizard™ and Biomarker Patterns™ software to find differential proteins and develop a classification tree for gastric cancer. A total of 34 mass peaks were identified. Six peaks at a mass-to-charge ratio (m/z) of 2873, 3163, 4526, 5762, 6121 and 7778 were used to construct the diagnostic model. The model effectively distinguished gastric cancer samples from control samples, achieving a sensitivity and specificity of 93.49 and 91.57%, respectively. In addition, we identified 3 of the 6 protein peaks at 2873, 6121 and 7778 m/z, which distinguished between stage I and stage II/III/IV gastric cancer. The model had an accuracy of 88.89% for the identification of stage I gastric cancer. In conclusion, the diagnostic model for the detection of serum proteins by SELDI-TOF-MS ProteinChip array technology correctly distinguishes gastric cancer from healthy samples, and has the ability to screen and distinguish between early gastric cancer from advanced gastric cancer. PMID:22427025

Li, Ping; Zhang, Dianliang; Guo, Chunbao

2012-06-01

44

Analyses by UPLC Q-TOF MS of products of aflatoxin B(1) after ozone treatment.  

PubMed

Analysing the products of ozone-treated aflatoxin B1 (AFB1) is essential in order to study the practical use of ozone treatment. In this paper, the products of AFB1 were investigated using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC Q-TOF MS). The products were well separated using UPLC, and the accurate masses of all the products were determined using Q-TOF MS. Finally, the possible pathways of fragmentation ion generation from the products of AFB1 and the structures of four products were proposed. From the view of the proposed structures of products, the C8-C9 double bond in the terminal furan ring was destroyed. According to the structure-activity relationship, the toxicity of products was significantly reduced compared with that of AFB1. The result indicated that ozone was an effective agent for degrading AFB1, and UPLC Q-TOF MS was a useful analytical tool for proposing and identifying a series of unknown products. PMID:24350699

Luo, Xiaohu; Wang, Ren; Wang, Li; Li, Yongfu; Zheng, Ruihang; Sun, Xiulan; Wang, Yong; Chen, Zhengxing; Tao, Guanjun

2014-01-01

45

Mass spectrometry: pneumococcal meningitis verified and Brucella species identified in less than half an hour.  

PubMed

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is currently being introduced for the rapid and accurate identification of bacteria. We describe 2 MALDI-TOF MS identification cases - 1 directly on spinal fluid and 1 on grown bacteria. Rapidly obtained results had great value for the continued treatment and for the elucidation of exposure. PMID:20429713

Nyvang Hartmeyer, Gitte; Kvistholm Jensen, Anne; Böcher, Sidsel; Damkjaer Bartels, Mette; Pedersen, Michael; Engell Clausen, Marianne; Abdul-Redha, Rawaa; Dargis, Rimtas; Schouenborg, Per; Højlyng, Niels; Kemp, Michael; Christensen, Jens Jørgen E

2010-09-01

46

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...

47

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

PubMed Central

Time-of-flight mass spectrometry (TOF MS) is increasingly used in proteomics research. Herein, we report on the development and characterization of a TOF MS instrument with improved sensitivity equipped with an electrodynamic ion funnel trap (IFT) that employs an automated gain control (AGC) capability. The IFT-TOF MS was coupled to a reversed-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. PMID:18512944

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

2009-01-01

48

Detection and quantification of bacterial spoilage in milk and pork meat using MALDI-TOF-MS and multivariate analysis.  

PubMed

Microbiological safety is one of the cornerstones of quality control in the food industry. Identification and quantification of spoilage bacteria in pasteurized milk and meat in the food industry currently relies on accurate and sensitive yet time-consuming techniques which give retrospective values for microbial contamination. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), a proven technique in the field of protein and peptide identification and quantification, may be a valuable alternative approach for the rapid assessment of microbial spoilage. In this work we therefore developed MALDI-TOF-MS as a novel analytical approach for the assessment of food that when combined with chemometrics allows for the detection and quantification of milk and pork meat spoilage bacteria. To develop this approach, natural spoilage of pasteurized milk and raw pork meat samples incubated at 15 °C and at room temperature, respectively, was conducted. Samples were collected for MALDI-TOF-MS analysis (which took 4 min per sample) at regular time intervals throughout the spoilage process, with concurrent calculation and documentation of reference total viable counts using traditional microbiological methods (these took 2 days). Multivariate statistical techniques such as principal component discriminant function analysis, canonical correlation analysis, partial least-squares (PLS) regression, and kernel PLS (KPLS) were used to analyze the data. The results from MALDI-TOF-MS combined with PLS or KPLS gave excellent bacterial quantification results for both milk and meat spoilage, and typical root mean squared errors for prediction in test spectra were between 0.53 and 0.79 log unit. Overall these novel findings strongly indicate that MALDI-TOF-MS when combined with chemometric approaches would be a useful adjunct for routine use in the milk and meat industry as a fast and accurate viable bacterial detection and quantification method. PMID:22698768

Nicolaou, Nicoletta; Xu, Yun; Goodacre, Royston

2012-07-17

49

Detection of Murine Toxoplasmosis Using Magnetic Bead-Based Serum Peptide Profiling by MALDI-TOF MS  

PubMed Central

Abstract Establishment of a rapid, highly specific, and accurate method for diagnosis of Toxoplasma gondii infection is essential to control and prevent zoonotic toxoplasmosis. In this study, a novel diagnostic strategy using magnetic bead-based serum peptide profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was developed. The serum peptides (samples I, II, and III) from T. gondii RH strain-infected mice at days 3, 6, and 9 post-infection (p.i.), and healthy mice were enriched by the optimized magnetic bead-based hydrophobic interaction (MB-HIC8). The mass spectrograms were acquired by MALDI-TOF MS, and analyzed by ClinProTools bioinformatics software from Bruker Daltonics. The diagnostic models from T. gondii RH-infected serum peptide profiling of samples I, II, and III were produced by genetic algorithms, and verified by cross-validation. The sample II model could correctly recognize T. gondii RH strain infection in mice at days 3, 6, and 9 p.i. with a sensitivity of 91.1% and a specificity of 96.7%., and also detect T. gondii ME49 strain-infected serum samples at days 3, 6, 9, and 12 p.i. with a sensitivity of 91.7%. The results of the present study suggest that serum peptide profiling by MALDI-TOF MS is a novel potential tool for the clinical diagnosis of acute T. gondii infection. PMID:22448678

Li, Jiping; Jin, Hongtao; Li, Lixia; Shang, Limin; Zhao, Yongkun; Wei, Feng; Liu, Yanjing; Qian, Jun

2012-01-01

50

Identification of the 'Streptococcus anginosus group' by matrix-assisted laser desorption ionization--time-of-flight mass spectrometry.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides rapid, accurate and cost-effective identification of a range of bacteria and is rapidly changing the face of routine diagnostic microbiology. However, certain groups of bacteria, for example streptococci (in particular viridans or non-haemolytic streptococci), are less reliably identified by this method. We studied the performance of MALDI-TOF MS for identification of the 'Streptococcus anginosus group' (SAG) to species level. In total, 116 stored bacteraemia isolates identified by conventional methods as belonging to the SAG were analysed by MALDI-TOF MS. Partial 16S rRNA gene sequencing, supplemented with sialidase activity testing, was performed on all isolates to provide 'gold standard' identification against which to compare MALDI-TOF MS performance. Overall, 100?% of isolates were correctly identified to the genus level and 93.1?% to the species level by MALDI-TOF MS. However, only 77.6?% were correctly identified to the genus level and 59.5?% to the species level by a MALDI-TOF MS direct transfer method alone. Use of a rapid in situ extraction method significantly improved identification rates when compared with the direct transfer method (P<0.001). We recommend routine use of this method to reduce the number of time-consuming full extractions required for identification of this group of bacteria by MALDI-TOF MS in the routine diagnostic laboratory. Only 22?% (1/9) of Streptococcus intermedius isolates were reliably identified by MALDI-TOF MS to the species level, even after full extraction. MALDI-TOF MS reliably identifies S. anginosus and Streptococcus constellatus to the species level but does not reliably identify S. intermedius. PMID:24917618

Woods, Katherine; Beighton, David; Klein, John L

2014-09-01

51

Detection of NDM-1, VIM-1, KPC, OXA-48, and OXA-162 Carbapenemases 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) is a potentially useful tool for the detection of antimicrobial resistance, especially that conferred by ?-lactamases. Here we describe a modification of a previously reported MALDI-TOF MS meropenem hydrolysis assay. The modified method was validated on 108 carbapenemase-producing members of the Enterobacteriaceae, two NDM-1-producing Acinetobacter baumannii isolates, and 35 carbapenem-resistant enterobacteria producing no carbapenemase. The detection of carbapenemases by MALDI-TOF MS seems to be a powerful, quick, and cost-effective method for microbiological laboratories. PMID:22553235

Študentová, Vendula; Walková, Radka; Žemli?ková, Helena; Jakub?, Vladislav; Chudá?ková, Eva; Gniadkowski, Marek; Pfeifer, Yvonne; Perry, John D.; Wilkinson, Kathryn; Bergerová, Tamara

2012-01-01

52

Spontaneous-Desorption Ionizer for a TOF-MS  

NASA Technical Reports Server (NTRS)

A time-of-flight mass spectrometer (TOF-MS) like the one mentioned in the immediately preceding article has been retrofitted with an ionizer based on a surface spontaneous-desorption process. This ionizer includes an electron multiplier in the form of a microchannel plate (MCP). Relative to an ionizer based on a hot-filament electron source, this ionizer offers advantages of less power consumption and greater mechanical ruggedness. The current density and stability characteristics of the electron emission of this ionizer are similar to those of a filament-based ionizer. In tests of various versions of this ionizer in the TOF-MS, electron currents up to 100 nA were registered. Currents of microamperes or more - great enough to satisfy requirements in most TOFMS applications - could be obtained by use of MCPs different from those used in the tests, albeit at the cost of greater bulk. One drawback of this ionizer is that the gain of the MCP decreases as a function of the charge extracted thus far; the total charge that can be extracted over the operational lifetime is about 1 coulomb. An MCP in the ion-detector portion of the TOF-MS is subject to the same limitation.

Schultz, J. Albert

2006-01-01

53

Proton Transfer Reaction Time-of-Flight Mass Spectrometric (PTR-TOF-MS) determination of volatile organic compounds (VOCs) emitted from a biomass fire developed under stable nocturnal conditions  

NASA Astrophysics Data System (ADS)

Combustion of solid and liquid fuels is the largest source of potentially toxic volatile organic compounds (VOCs), which can strongly affect health and the physical and chemical properties of the atmosphere. Among combustion processes, biomass burning is one of the largest at global scale. We used a Proton Transfer Reaction “Time-of-Flight” Mass Spectrometer (PTR-TOF-MS), which couples high sensitivity with high mass resolution, for real-time detection of multiple VOCs emitted by burned hay and straw in a barn located near our measuring station. We detected 132 different organic ions directly attributable to VOCs emitted from the fire. Methanol, acetaldehyde, acetone, methyl vinyl ether (MVE), acetic acid and glycolaldehyde dominated the VOC mixture composition. The time-course of the 25 most abundant VOCs, representing ?85% of the whole mixture of VOCs, was associated with that of carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4) emissions. The strong linear relationship between the concentrations of pyrogenic VOC and of a reference species (i.e. CO) allowed us to compile a list of emission ratios (ERs) and emission factors (EFs), but values of ER (and EF) were overestimated due to the limited mixing of the gases under the stable (non-turbulent) nocturnal conditions. In addition to the 25 most abundant VOCs, chemical formula and concentrations of the residual, less abundant VOCs in the emitted mixture were also estimated by PTR-TOF-MS. Furthermore, the evolution of the complex combustion process was described on the basis of the diverse types of pyrogenic gases recorded.

Brilli, Federico; Gioli, Beniamino; Ciccioli, Paolo; Zona, Donatella; Loreto, Francesco; Janssens, Ivan A.; Ceulemans, Reinhart

2014-11-01

54

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...

55

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

56

MALDI-TOF MS analysis of lipids from cells, tissues and body fluids.  

PubMed

Many diseases as atherosclerosis and metabolic dysfunctions are known to correlate with changes of the lipid profile of tissues and body fluids. Therefore, the importance of reliable methods of lipid analysis is obvious. Although matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) was so far primarily used for protein analysis, this method has itself proven to be very useful in lipid analysis, too. This review provides an overview of applications of MALDI-TOF MS in lipid analysis and summarizes the specific advantages and drawbacks of this modern soft-ionization method. The focus will be on the analysis of body fluids and cells as well as the diagnostic potential of the method in the lipid field. It will be shown that MALDI-TOF mass spectra can be recorded in a very short time and provide important information on the lipid as well as the fatty acyl composition of the lipids of an unknown sample. However, it will also be shown that only selected lipid classes (in particular those with quaternary ammonia groups as phosphatidylcholine) are detected if crude mixtures are analyzed as they are more sensitively detectable than other ones. This review ends with a short outlook emphasizing current methodological developments. PMID:18751926

Fuchs, Beate; Schiller, Jürgen

2008-01-01

57

Comparative analysis of Gram's stain, PNA-FISH and Sepsityper with MALDI-TOF MS for the identification of yeast direct from positive blood cultures.  

PubMed

Fungaemia diagnosis could be improved by reducing the time to identification of yeast from blood cultures. This study aimed to evaluate three rapid methods for the identification of yeast direct from blood cultures; Gram's stain analysis, the AdvanDX Peptide Nucleic Acid in Situ Hybridisation Yeast Traffic Light system (PNA-FISH YTL) and Bruker Sepsityper alongside matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI-TOF MS). Fifty blood cultures spiked with a known single yeast strain were analysed by blinded operators experienced in each method. Identifications were compared with MALDI-TOF MS CHROMagar Candida culture and ITS rRNA sequence-based identifications. On first attempt, success rates of 96% (48/50) and 76% (36/50) were achieved using PNA-FISH YTL and Gram's stain respectively. MALDI-TOF MS demonstrated a success rate of 56% (28/50) when applying manufacturer's species log score thresholds and 76% (38/50) using in-house parameters, including lowering the species log score threshold to >1.5. In conclusion, PNA-FISH YTL demonstrated a high success rate successfully identifying yeast commonly encountered in fungaemia. Sepsityper(™) with MALDI-TOF MS was accurate but increased sensitivity is required. Due to the misidentification of commonly encountered yeast Gram's stain analysis demonstrated limited utility in this setting. PMID:24862948

Gorton, Rebecca L; Ramnarain, P; Barker, K; Stone, N; Rattenbury, S; McHugh, T D; Kibbler, C C

2014-10-01

58

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Identification of Yeasts Is Contingent on Robust Reference Spectra  

Microsoft Academic Search

BackgroundMatrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for yeast identification is limited by the requirement for protein extraction and for robust reference spectra across yeast species in databases. We evaluated its ability to identify a range of yeasts in comparison with phenotypic methods.MethodsMALDI-TOF MS was performed on 30 reference and 167 clinical isolates followed by prospective examination

Angie Pinto; Catriona Halliday; Melissa Zahra; Sebastian van Hal; Tom Olma; Krystyna Maszewska; Jonathan R. Iredell; Wieland Meyer; Sharon C.-A. Chen; Markus M. Heimesaat

2011-01-01

59

A comparative study of amino acid measurement in leaf extracts by gas chromatography-time of flight-mass spectrometry and high performance liquid chromatography with fluorescence detection  

Microsoft Academic Search

Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) has become a promising technique for simultaneous\\u000a and rapid analysis of small metabolites in complex mixtures. The aim of this work was to establish the quantitative nature\\u000a of the information generated by amino acid analysis of crude leaf extracts using GC-TOF-MS. Dried aliquots of methanol\\/water\\u000a extracts of Arabidopsis leaves were analysed in

Graham Noctor; Gaëlle Bergot; Caroline Mauve; Dorothée Thominet; Caroline Lelarge-Trouverie; Jean-Louis Prioul

2007-01-01

60

Proteomic analysis of Acinetobacter lwoffii K24 by 2-D gel electrophoresis and electrospray ionization quadrupole-time of flight mass spectrometry  

Microsoft Academic Search

The MS\\/MS analysis by Electrospray ionization quadrupole-time of flight mass spectrometry (ESI-Q-TOF MS) was applied to identify proteins in proteome analysis of bacteria whose genomes are not known. The protein identification by ESI-Q-TOF MS was performed sequentially by database search and then de novo sequencing using MS\\/MS spectra. Soil bacteria having unanalyzed genome, Acinetobacter lwoffii K24 is an aniline degrading

Eun-A Kim; Jin Young Kim; Soo-Jung Kim; Kyeong Ryang Park; Hae-Jin Chung; Sun-Hee Leem; Seung Il Kim

2004-01-01

61

Species differentiation within the Staphylococcus intermedius group using a refined MALDI-TOF MS database.  

PubMed

Among coagulase-positive staphylococci of animal origin, the members of the Staphylococcus intermedius-group (SIG: S. intermedius, Staphylococcus pseudintermedius and Staphylococcus delphini) are important opportunistic pathogens in different animal hosts and occasionally in humans. However, the unambiguous species diagnosis of SIG is often challenging. Therefore, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) -based SIG-identification with Bruker Microflex LT in combination with Biotyper 3.0 software (Bruker Daltonics, Bremen, Germany) was evaluated using (i) the original database content and (ii) the database after extension with distinct hierarchical clustered reference spectra for 60 SIG. A convenience sample comprising 200 isolates was used to compare both database performances. As a result, 17 isolates initially diagnosed as S. intermedius with the current content of the Bruker database were identified as S. pseudintermedius by applying the in-house reference spectra extended version. Furthermore, a significant improvement (average rise of log score value: 0.24) of the SIG identification score values was achieved, emphasizing that further sequence-based refinement of the Bruker database content allows improvement of MALDI-TOF MS-based identification. PMID:24807701

Murugaiyan, J; Walther, B; Stamm, I; Abou-Elnaga, Y; Brueggemann-Schwarze, S; Vincze, S; Wieler, L H; Lübke-Becker, A; Semmler, T; Roesler, U

2014-10-01

62

Identification of Corynebacterium spp. isolated from bovine intramammary infections by matrix-assisted laser desorption ionization-time of flight mass spectrometry.  

PubMed

Corynebacterium species (spp.) are among the most frequently isolated pathogens associated with subclinical mastitis in dairy cows. However, simple, fast, and reliable methods for the identification of species of the genus Corynebacterium are not currently available. This study aimed to evaluate the usefulness of matrix-assisted laser desorption ionization/mass spectrometry (MALDI-TOF MS) for identifying Corynebacterium spp. isolated from the mammary glands of dairy cows. Corynebacterium spp. were isolated from milk samples via microbiological culture (n=180) and were analyzed by MALDI-TOF MS and 16S rRNA gene sequencing. Using MALDI-TOF MS methodology, 161 Corynebacterium spp. isolates (89.4%) were correctly identified at the species level, whereas 12 isolates (6.7%) were identified at the genus level. Most isolates that were identified at the species level with 16 S rRNA gene sequencing were identified as Corynebacterium bovis (n=156; 86.7%) were also identified as C. bovis with MALDI-TOF MS. Five Corynebacterium spp. isolates (2.8%) were not correctly identified at the species level with MALDI-TOF MS and 2 isolates (1.1%) were considered unidentified because despite having MALDI-TOF MS scores >2, only the genus level was correctly identified. Therefore, MALDI-TOF MS could serve as an alternative method for species-level diagnoses of bovine intramammary infections caused by Corynebacterium spp. PMID:25086477

Gonçalves, Juliano Leonel; Tomazi, Tiago; Barreiro, Juliana Regina; Braga, Patrícia Aparecida de Campos; Ferreira, Christina Ramires; Araújo Junior, João Pessoa; Eberlin, Marcos Nogueira; dos Santos, Marcos Veiga

2014-09-17

63

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

64

MALDI-TOF Mass Spectrometry of Naturally-Occurring Mixtures of Mono- and Di-rhamnolipids  

Technology Transfer Automated Retrieval System (TEKTRAN)

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been developed for high-throughput screening of naturally-occurring mixtures of rhamnolipids from Pseudomonas spp. Mono- and di-rhamnolipids are readily distinguished by characteristic molecular adduct i...

65

High-throughput identification of bacteria and yeast by matrix-assisted laser desorption ionization-time of flight mass spectrometry in conventional medical microbiology laboratories.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is suitable for high-throughput and rapid diagnostics at low costs and can be considered an alternative for conventional biochemical and molecular identification systems in a conventional microbiological laboratory. First, we evaluated MALDI-TOF MS using 327 clinical isolates previously cultured from patient materials and identified by conventional techniques (Vitek-II, API, and biochemical tests). Discrepancies were analyzed by molecular analysis of the 16S genes. Of 327 isolates, 95.1% were identified correctly to genus level, and 85.6% were identified to species level by MALDI-TOF MS. Second, we performed a prospective validation study, including 980 clinical isolates of bacteria and yeasts. Overall performance of MALDI-TOF MS was significantly better than conventional biochemical systems for correct species identification (92.2% and 83.1%, respectively) and produced fewer incorrect genus identifications (0.1% and 1.6%, respectively). Correct species identification by MALDI-TOF MS was observed in 97.7% of Enterobacteriaceae, 92% of nonfermentative Gram-negative bacteria, 94.3% of staphylococci, 84.8% of streptococci, 84% of a miscellaneous group (mainly Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella [HACEK]), and 85.2% of yeasts. MALDI-TOF MS had significantly better performance than conventional methods for species identification of staphylococci and genus identification of bacteria belonging to HACEK group. Misidentifications by MALDI-TOF MS were clearly associated with an absence of sufficient spectra from suitable reference strains in the MALDI-TOF MS database. We conclude that MALDI-TOF MS can be implemented easily for routine identification of bacteria (except for pneumococci and viridans streptococci) and yeasts in a medical microbiological laboratory. PMID:20053859

van Veen, S Q; Claas, E C J; Kuijper, Ed J

2010-03-01

66

High-Throughput Identification of Bacteria and Yeast by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry in Conventional Medical Microbiology Laboratories ?  

PubMed Central

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is suitable for high-throughput and rapid diagnostics at low costs and can be considered an alternative for conventional biochemical and molecular identification systems in a conventional microbiological laboratory. First, we evaluated MALDI-TOF MS using 327 clinical isolates previously cultured from patient materials and identified by conventional techniques (Vitek-II, API, and biochemical tests). Discrepancies were analyzed by molecular analysis of the 16S genes. Of 327 isolates, 95.1% were identified correctly to genus level, and 85.6% were identified to species level by MALDI-TOF MS. Second, we performed a prospective validation study, including 980 clinical isolates of bacteria and yeasts. Overall performance of MALDI-TOF MS was significantly better than conventional biochemical systems for correct species identification (92.2% and 83.1%, respectively) and produced fewer incorrect genus identifications (0.1% and 1.6%, respectively). Correct species identification by MALDI-TOF MS was observed in 97.7% of Enterobacteriaceae, 92% of nonfermentative Gram-negative bacteria, 94.3% of staphylococci, 84.8% of streptococci, 84% of a miscellaneous group (mainly Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella [HACEK]), and 85.2% of yeasts. MALDI-TOF MS had significantly better performance than conventional methods for species identification of staphylococci and genus identification of bacteria belonging to HACEK group. Misidentifications by MALDI-TOF MS were clearly associated with an absence of sufficient spectra from suitable reference strains in the MALDI-TOF MS database. We conclude that MALDI-TOF MS can be implemented easily for routine identification of bacteria (except for pneumococci and viridans streptococci) and yeasts in a medical microbiological laboratory. PMID:20053859

van Veen, S. Q.; Claas, E. C. J.; Kuijper, Ed J.

2010-01-01

67

Characterization of mustard seeds and paste by DART ionization with time-of-flight mass spectrometry.  

PubMed

Direct analysis in real time (DART) is a novel technique with great potential for rapid screening analysis. The DART ionization method coupled with high-resolution time-of-flight mass spectrometry (TOF-MS) has been used for characterization of mustard seeds and table mustard. The possibility to use DART to analyse glucosinolates was confirmed on determination of sinalbin (4-hydroxybenzyl glucosinolate). The DART-TOF-MS method was optimized and validated. A set of samples of mustard seeds and mustard products was analyzed. High-performance liquid chromatography and DART-TOF-MS were used to determine glucosinolates in mustard seeds and compared. The correlation equation between these methods was DART?=?0.797*HPLC?+?6.987, R(2) ?=?0.972. The DART technique seems to be a suitable method for evaluation of the quality of mustard seeds and mustard products. PMID:25230177

Prchalová, Jana; Kova?ík, František; Šev?ík, Rudolf; ?ížková, Helena; Rajchl, Aleš

2014-09-01

68

Probing Combustion Chemistry in a Miniature Shock Tube with Synchrotron VUV Photo Ionization Mass Spectrometry.  

PubMed

Tunable synchrotron-sourced photoionization time-of-flight mass spectrometry (PI-TOF-MS) is an important technique in combustion chemistry, complementing lab-scale electron impact and laser photoionization studies for a wide variety of reactors, typically at low pressure. For high-temperature and high-pressure chemical kinetics studies, the shock tube is the reactor of choice. Extending the benefits of shock tube/TOF-MS research to include synchrotron sourced PI-TOF-MS required a radical reconception of the shock tube. An automated, miniature, high-repetition-rate shock tube was developed and can be used to study high-pressure reactive systems (T > 600 K, P < 100 bar) behind reflected shock waves. In this paper, we present results of a PI-TOF-MS study at the Advanced Light Source at Lawrence Berkeley National Laboratory. Dimethyl ether pyrolysis (2% CH3OCH3/Ar) was observed behind the reflected shock (1400 < T5 < 1700 K, 3 < P5 < 16 bar) with ionization energies between 10 and 13 eV. Individual experiments have extremely low signal levels. However, product species and radical intermediates are well-resolved when averaging over hundreds of shots, which is ordinarily impractical in conventional shock tube studies. The signal levels attained and data throughput rates with this technique are comparable to those with other synchrotron-based PI-TOF-MS reactors, and it is anticipated that this high pressure technique will greatly complement those lower pressure techniques. PMID:25594229

Lynch, Patrick T; Troy, Tyler P; Ahmed, Musahid; Tranter, Robert S

2015-02-17

69

Accurate identification of Culicidae at aquatic developmental stages by MALDI-TOF MS profiling.  

PubMed

BackgroundThe identification of mosquito vectors is generally based on morphological criteria, but for aquatic stages, morphological characteristics may be missing, leading to incomplete or incorrect identification. The high cost of molecular biology techniques requires the development of an alternative strategy. In the last decade, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling has proved to be efficient for arthropod identification at the species level.MethodsTo investigate the usefulness of MALDI-TOF MS for the identification of mosquitoes at aquatic stages, optimizations of sample preparation, diet, body parts and storage conditions were tested. Protein extracts of whole specimens from second larval stage to pupae were selected for the creation of a reference spectra database. The database included a total of 95 laboratory-reared specimens of 6 mosquito species, including Anopheles gambiae (S form), Anopheles coluzzi (M form), Culex pipiens pipiens, Culex pipiens molestus, Aedes aegypti and 2 colonies of Aedes albopictus.ResultsThe present study revealed that whole specimens at aquatic stages produced reproducible and singular spectra according to the mosquito species. Moreover, MS protein profiles appeared weakly affected by the diet provided. Despite the low diversity of some MS profiles, notably for cryptic species, clustering analyses correctly classified all specimens tested at the species level followed by the clustering of early vs. late aquatic developmental stages. Discriminant mass peaks were recorded for the 6 mosquito species analyzed at larval stage 3 and the pupal stage. Querying against the reference spectra database of 149 new specimens at different aquatic stages from the 6 mosquito species revealed that 147 specimens were correctly identified at the species level and that early and late developmental stages were also distinguished.ConclusionsThe present work highlights that MALDI-TOF MS profiling may be useful for the rapid and reliable identification of mosquito species at aquatic stages. With this proteomic tool, it becomes now conceivable to survey mosquito breeding sites prior to the mosquitoes¿ emergence and to adapt anti-vectorial measures according to the mosquito fauna detected. PMID:25442218

Dieme, Constentin; Yssouf, Amina; Vega-Rúa, Anubis; Berenger, Jean-Michel; Failloux, Anna-Bella; Raoult, Didier; Parola, Philippe; Almeras, Lionel

2014-12-01

70

Mass spectrometry.  

NASA Technical Reports Server (NTRS)

Review of the current state of mass spectrometry, indicating its unique importance for advanced scientific research. Mass spectrometry applications in computer techniques, gas chromatography, ion cyclotron resonance, molecular fragmentation and ionization, and isotope labeling are covered. Details are given on mass spectrometry applications in bio-organic chemistry and biomedical research. As the subjects of these applications are indicated alkaloids, carbohydrates, lipids, terpenes, quinones, nucleic acid components, peptides, antibiotics, and human and animal metabolisms. Particular attention is given to the mass spectra of organo-inorganic compounds, inorganic mass spectrometry, surface phenomena such as secondary ion and electron emission, and elemental and isotope analysis. Further topics include mass spectrometry in organic geochemistry, applications in geochronology and cosmochemistry, and organic mass spectrometry.

Burlingame, A. L.; Johanson, G. A.

1972-01-01

71

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

72

Early Diagnosis of Irkut Virus Infection Using Magnetic Bead-Based Serum Peptide Profiling by MALDI-TOF MS in a Mouse Model  

PubMed Central

Early diagnosis is important for the prompt post-exposure prophylaxis of lyssavirus infections. To diagnose Irkut virus (IRKV) infection during incubation in mice, a novel method using magnetic bead-based serum peptide profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been established. For this test, serum peptides were concentrated by adsorption to and elution from the magnetic bead-based weak cation ion exchanger. Mass spectrograms obtained by MALDI-TOF MS were analyzed using ClinProTools bioinformatics software. Construction of the diagnostic model was performed using serum samples from mice infected with IRKV and rabies virus (RABV) BD06, Flury-LEP, and SRV9 (as controls). The method accurately diagnosed sera 2, 4 and 8 days after IRKV and RABV infections. The sensitivity, specificity, and total accuracy of diagnosis were 86.7%, 95.2%, and 92.9%, respectively. However, IRKV could not be differentiated from RABV 1 day after infection. The results of the present study indicate that serum peptide profiling by MALDI-TOF MS is a promising technique for the early clinical diagnosis of lyssavirus infections and needs to be further tested in humans and farm animals. PMID:24670473

Li, Nan; Liu, Ye; Hao, Zhuo; Zhang, Shoufeng; Hu, Rongliang; Li, Jiping

2014-01-01

73

MALDI-TOF MS for the identification of veterinary non-C. neoformans-C. gattii Cryptococcus spp. isolates from Italy.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) offers an effective alternative to phenotypic and molecular methods for the rapid identification of microorganisms. Our aim in this study was to create an in-house library for a set of strains of nine uncommonly reported human and animal cryptococcal species, including Cryptococcus adeliensis, C. albidosimilis, C. albidus, C. aureus, C. carnescens, C. laurentii, C. magnus, C. victoriae and C. uniguttulatus, and to use this library to make timely and correct identifications using MALDI-TOF MS for use in routine laboratory diagnostics. Protein extracts obtained via the formic acid extraction method of 62 veterinary non-C. neoformans-C. gattii cryptococcal isolates were studied. The obtained mass spectra correctly grouped all 62 studied isolates according to species identification previously obtained by internal transcribe spacer sequence analysis. The in-house database was than exported and successfully uploaded to the Microflex LT (Maldi Biotyper; Bruker Daltonics) instrument at a different diagnostic laboratory in Italy. Scores >2.7 obtained from isolates reanalyzed in the latter laboratory supported the high reproducibility of the method. The possibility of creating and transferring an in-house library adds to the usefulness MALDI-TOF MS an important tool for the rapid and inexpensive identification of pathogenic and saprophytic fungi as required for differential diagnosis of human and animal mycoses. PMID:24951721

Danesi, Patrizia; Drigo, Ilenia; Iatta, Roberta; Firacative, Carolina; Capelli, Gioia; Cafarchia, Claudia; Meyer, Wieland

2014-08-01

74

Reducing time to identification of positive blood cultures with MALDI-TOF MS analysis after a 5-h subculture.  

PubMed

Speeding up the turn-around time of positive blood culture identifications is essential in order to optimize the treatment of septic patients. Several sample preparation techniques have been developed allowing direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identification of positive blood cultures. Yet, the hands-on time restrains their routine workflow. In this study, we evaluated an approach whereby MALDI-TOF MS identification without any additional steps was carried out on short subcultured colonies from positive blood bottles with the objective of allowing results reporting on the day of positivity detection. Over a 7-month period in 2012, positive blood cultures detected by 9 am with an automated system were inoculated onto a Columbia blood agar and processed after a 5-h incubation on a MALDI-TOF MicroFlex platform (Bruker Daltonik GmbH). Single-spotted colonies were covered with 1 ?l formic acid and 1 ?l matrix solution. The results were compared to the validated identification techniques. A total of 925 positive blood culture bottles (representing 470 bacteremic episodes) were included. Concordant identification was obtained in 727 (81.1 %) of the 896 monomicrobial blood cultures, with failure being mostly observed with anaerobes and yeasts. In 17 episodes of polymicrobic bacteremia, the identification of one of the two isolates was achieved in 24/29 (82.7 %) positive cultures. Routine implementation of MALDI-TOF MS identification on young positive blood subcultures provides correct results to the clinician in more than 80 % of the bacteremic episodes and allows access to identification results on the day of blood culture positivity detection, potentially accelerating the implementation of targeted clinical treatments. PMID:25252627

Verroken, A; Defourny, L; Lechgar, L; Magnette, A; Delmée, M; Glupczynski, Y

2014-09-25

75

MALDI-TOF mass spectrometry applied to identifying species of insect-pathogenic fungi from the Metarhizium anisopliae complex  

Technology Transfer Automated Retrieval System (TEKTRAN)

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has proven to be a powerful tool for taxonomic resolution of microorganisms. In this proof-of-concept study, we assessed the effectiveness of this technique to track the current gene sequence-based phylogenet...

76

Performance of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Bacterial Strains Routinely Isolated in a Clinical Microbiology Laboratory ?  

PubMed Central

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been introduced in diagnostic microbiology laboratories for the identification of bacterial and yeast strains isolated from clinical samples. In the present study, we prospectively compared MALDI-TOF MS to the conventional phenotypic method for the identification of routine isolates. Colonies were analyzed by MALDI-TOF MS either by direct deposition on the target plate or after a formic acid-acetonitrile extraction step if no valid result was initially obtained. Among 1,371 isolates identified by conventional methods, 1,278 (93.2%) were putatively identified to the species level by MALDI-TOF MS and 73 (5.3%) were identified to the genus level, but no reliable identification was obtained for 20 (1.5%). Among the 1,278 isolates identified to the species level by MALDI-TOF MS, 63 (4.9%) discordant results were initially identified. Most discordant results (42/63) were due to systematic database-related taxonomical differences, 14 were explained by poor discrimination of the MALDI-TOF MS spectra obtained, and 7 were due to errors in the initial conventional identification. An extraction step was required to obtain a valid MALDI-TOF MS identification for 25.6% of the 1,278 valid isolates. In conclusion, our results show that MALDI-TOF MS is a fast and reliable technique which has the potential to replace conventional phenotypic identification for most bacterial strains routinely isolated in clinical microbiology laboratories. PMID:20220166

Bizzini, A.; Durussel, C.; Bille, J.; Greub, G.; Prod'hom, G.

2010-01-01

77

Extraction and sequencing of human and Neanderthal mature enamel proteins using MALDI-TOF/TOF MS  

E-print Network

Extraction and sequencing of human and Neanderthal mature enamel proteins using MALDI-TOF/TOF MS Enamel Neanderthal MALDI-TOF-TOF a b s t r a c t We report here the first results of a method to extract and sequence mature enamel proteins from modern human and Neanderthal tooth enamel. Using MALDI-TOF/TOF mass

Smith, Tanya M.

78

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. PMID:22925589

2012-01-01

79

Species Identification of Clinical Prevotella Isolates by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry  

PubMed Central

The performance of matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) for species identification of Prevotella was evaluated and compared with 16S rRNA gene sequencing. Using a Bruker database, 62.7% of the 102 clinical isolates were identified to the species level and 73.5% to the genus level. Extension of the commercial database improved these figures to, respectively, 83.3% and 89.2%. MALDI-TOF MS identification of Prevotella is reliable but needs a more extensive database. PMID:22301022

Soetens, Oriane; De Bel, Annelies; Echahidi, Fedoua; Vancutsem, Ellen; Vandoorslaer, Kristof; Piérard, Denis

2012-01-01

80

Powerful GC-TOF-MS Techniques for Screening, Identification and Quantification of Halogenated Natural Products  

PubMed Central

Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC TOFMS) and gas chromatography/high-resolution time-of-flight mass spectrometry (GC-HRT) were used to detect and identify halogenated natural products (HNPs) in tissue homogenate, in this case brominated analytes present in a marine snail. Two classes of brominated anthropogenic compounds, polybrominated diphenyl ethers (PBDEs) and brominated dibenzofurans, were analyzed for comparison. Following conventional preparation, the sample was analyzed using GC×GC-TOF-MS. Isotope ratio scripts were used to compile a list of putatively brominated analytes from amongst the thousands of features resolved in the two-dimensional chromatogram. The structured nature of the chromatogram was exploited to propose identifications for several classes of brominated compounds, and include additional candidates that fell marginally outside the script tolerances. The sample was subsequently analyzed by GC-HRT. The high-resolution mass spectral data confirmed many formula assignments, facilitated confident assignment of an alternate formula when an original proposal did not hold, and enabled unknown identification. Identified HNPs include hydroxylated and methoxylated PBDE analogs, polybrominated dibenzo-p-dioxins (PBDDs) and hydroxyl-PBDDs, permitting the environmental occurrence and fate of such compounds to be studied. PMID:24349937

S. Haglund, Peter; Löfstrand, Karin; Siek, Kevin; Asplund, Lillemor

2013-01-01

81

Analysis of raw hams using SELDI-TOF-MS to predict the final quality of dry-cured hams.  

PubMed

The relationship between protein profiles of Gluteus medius (GM) muscles of raw hams obtained from 4 pure breed pigs (Duroc, Large White, Landrace, and Piétrain) with the final quality of the Semimembranosus and Biceps femoris muscles of dry-cured hams was investigated. As expected, Duroc hams showed higher levels of marbling and intramuscular fat content than the other breeds. Piétrain hams were the leanest and most conformed, and presented the lowest salt content in dry-cured hams. Even if differences in the quality traits (colour, water activity, texture, composition, intramuscular fat, and marbling) of dry-cured hams were observed among the studied breeds, only small differences in the sensory attributes were detected. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) was used to obtain the soluble protein profiles of GM muscles. Some associations between protein peaks obtained with SELDI-TOF-MS and quality traits, mainly colour (b*) and texture (F(0), Y(2), Y(90)) were observed. Candidate protein markers for the quality of processed dry-cured hams were identified. PMID:23036942

Marcos, B; Gou, P; Serra, X; Guàrdia, M D; Zhen, Z Y; Hortós, M; Mach, N; te Pas, M F W; Keuning, E; Kruijt, L; Font i Furnols, M; Arnau, J

2013-02-01

82

Establishing serological classification tree model in rheumatoid arthritis using combination of MALDI-TOF-MS and magnetic beads.  

PubMed

To establish a serological classification tree model for rheumatoid arthritis (RA), protein/peptide profiles of serum were detected by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS) combined with weak cationic exchange (WCX) from Cohort 1, including 65 patients with RA and 41 healthy controls (HC). The samples were randomly divided into a training set and a test set. Twenty-four differentially expressed peaks (P < 0.05) were identified in the training set and 4 of them, namely m/z 3,939, 5,906, 8,146, and 8,569 were chosen to set up our model. This model exhibited a sensitivity of 100.0 % and a specificity of 96.0 % for differentiating RA patients from HC. The test set reproduced these high levels of sensitivity and specificity, which were 100.0 and 81.2 %, respectively. Cohort 2, which include 228 RA patients, was used to further verify the classification efficiency of this model. It came out that 97.4 % of them were classified as RA by this model. In conclusion, MALDI-TOF-MS combined with WCX magnetic beads was a powerful method for constructing a classification tree model for RA, and the model we established was useful in recognizing RA. PMID:24292670

Yan, Zhang; Chaojun, Hu; Chuiwen, Deng; Xiaomei, Leng; Xin, Zhang; Yongzhe, Li; Fengchun, Zhang

2015-02-01

83

Monoaromatic 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 monoaromatic complexity in gasoline, gasoline vapours and urban air. A comparison of comprehensive gas chromatography (GC×GC) 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 monoaromatic isomers isolated in gasoline during a 200 s GC separation. Higher analytical resolution for gasoline was obtained using GC×GC, isolating 130 monoaromatics, using combined column retention behaviour for analyte identification. Analysis of urban air using GC×GC indicated the presence of 147 monoaromatic species with up to 8 carbon substituents on the ring. In conventional separations such as single column GC-FID, heartcut GC and GC/MS these compounds are hidden by the constant co-elutions occurring in low volatility regions. The vast number of low concentration species in the higher boiling point range make it impossible to completely speciate all analytes present using single column methodologies. Comparison of 2D GC×GC chromatograms for air and gasoline vapours demonstrated visually the impact of evaporative emission sources in urban environments. The potential contribution of larger monoaromatic compounds as precursors to both photochemical ozone and secondary organic aerosol is discussed along with the implications on modelling OH chemistry in polluted air.

Hamilton, Jacqueline F.; Lewis, Alastair C.

84

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

85

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

2009-01-01

86

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. PMID:24086492

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

2013-01-01

87

Herbal medicine analysis by liquid chromatography/time-of-flight mass spectrometry.  

PubMed

The fact that the effects of herbal medicines (HMs) are brought about by their chemical constituents has created a critical demand for powerful analytical tools performing the chemical analysis to assure their efficacy, safety and quality. Liquid chromatography coupled to mass spectrometry (LC-MS) is an excellent technique to analyze multi-components in complex herbal matrices. Due to its inherent characteristics of accurate mass measurements and high resolution, time-of-flight (TOF) MS is well-suited to this field, especially for qualitative applications. The purpose of this article is to provide an overview on the potential of TOF, including the hybrid quadrupole- and ion trap-TOF (QTOF and IT-TOF), hyphenated to LC for chemical analysis in HMs or HM-treated biological samples. The peculiarities of LC-(Q/IT)TOF-MS for the analysis of HMs are discussed first, including applied stationary phase, mobile-phase selection, accurate mass measurements, fragmentation and selectivity. The final section is devoted to describing the applicability of LC-(Q/IT)TOF-MS to routine analysis of multi-components, including target and non-target (unknown) compounds, in herbal samples, emphasizing both the advantages and limitations of this approach for qualitative and quantitative purposes. The potential and future trends of fast high-performance liquid chromatography (HPLC) (e.g. rapid resolution LC and ultra-performance LC) coupled to (Q)TOF-MS for chemical analysis of HMs are highlighted. PMID:19501368

Zhou, Jian-Liang; Qi, Lian-Wen; Li, Ping

2009-10-30

88

UPLC-TOF-MS Characterization and Identification of Bioactive Iridoids in Cornus mas Fruit  

PubMed Central

Cornus mas L. is indigenous to Europe and parts of Asia. Although Cornus is widely considered to be an iridoid rich genera, only two iridoids have been previously found in this plant. The lack of information on taxonomically and biologically active iridoids prompted us to develop and optimize an analytical method for characterization of additional phytochemicals in C. mas fruit. An ultra performance liquid chromatography (UPLC) coupled with photodiode array spectrophotometry (PDA) and electrospray time-of-flight mass spectrometry (ESI-TOF-MS) was employed and mass parameters were optimized. Identification was made by elucidating the mass spectral data and further confirmed by comparing retention times and UV spectra of target peaks with those of reference compounds. Primary DNA damage and antigenotoxicity tests in E. coli PQ37 were used to screen the iridoids for biological activity. As a result, ten phytochemicals were identified, including iridoids loganic acid, loganin, sweroside, and cornuside. Nine of these were reported for the first time from C. mas fruit. The iridoids did not induce SOS repair of DNA, indicating a lack of genotoxic activity in E. coli PQ37. However, loganin, sweroside, and cornuside did reduce the amount of DNA damage caused by 4-nitroquinoline 1-oxide, suggesting potential antigenotoxic activity. PMID:24228188

West, Brett J.; Jensen, C. Jarakae

2013-01-01

89

HPLC-Q-TOF-MS Identification of Antioxidant and Antihypertensive Peptides Recovered from Cherry (Prunus cerasus L.) Subproducts.  

PubMed

The processing of fruits, such as cherries, is characterized by generating a lot of waste material such as fruit stones, skins, etc. To contribute to environmental sustainability, it is necessary to recover these residues. Cherry stones contain seeds with a significant amount of proteins that are underused and undervalued. The aim of this work was to extract cherry seed proteins, to evaluate the presence of bioactive peptides, and to identify them by mass spectrometry. The digestion of cherry seed proteins was optimized, and three different enzymes were employed: Alcalase, Thermolysin, and Flavourzyme. Peptide extracts obtained by the digestion of the cherry seed protein isolate with Alcalase and Thermolysin yielded the highest antioxidant and antihypertensive capacities. Ultrafiltration of hydrolysates allowed obtaining fractions with high antioxidant and antihypertensive capabilities. HPLC-Q-TOF-MS together with bioinformatics tools enabled one to identify peptides in these fractions. PMID:25599260

García, María Concepción; Endermann, Jochan; González-García, Estefanía; Marina, María Luisa

2015-02-11

90

Chemical profiling of Wu-tou decoction by UPLC-Q-TOF-MS.  

PubMed

Wu-tou decoction (WTD), a traditional Chinese medicine (TCM) formula, is composed of Aconiti Radix Cocta, Ephedrae Herba, Paeoniae Radix Alba, Astragali Radix and Glycyrrhiza Radix Preparata, and it has been used for more than a thousand years to treat rheumatic arthritis, rheumatoid arthritis and pain of joints, while the active constitutions of WTD are unclear. In this research, an ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method in both positive and negative ion mode was established to investigate the major constitutions in WTD. A Waters ACQUITY UPLC BEH C18 column was used to separate the aqueous extract of WTD. Acetonitrile and 0.1% aqueous formic acid (v/v) were used as the mobile phase. 74 components including alkaloids, monoterpene glycosides, triterpene saponins, flavones and flavone glycosides were identified or tentatively characterized in WTD based on the accurate mass within 15 ppm error and tandem MS behavior. All the constitutions were also detected in the corresponding individual herbs. These results will provide a basis for further study in vivo of WTD and the information of potential new drug structure for treating rheumatic arthritis and rheumatoid arthritis. PMID:24274266

Qi, Yao; Li, Shizhe; Pi, Zifeng; Song, Fengrui; Lin, Na; Liu, Shu; Liu, Zhiqiang

2014-01-01

91

Qualitative and quantitative analyses of alkaloids in Uncaria species by UPLC-ESI-Q-TOF/MS.  

PubMed

An ultra performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (Q-TOF/MS) method has been optimized and established for the rapid analysis of the alkaloids in 22 samples originating from five Uncaria (U.) species. The accurate mass measurement of all the protonated molecules and subsequent fragment ions offers higher quality structural information for the interpretation of fragmentation pathways of the various groups of alkaloids. A total of 19 oxindole alkaloids, 16 indole alkaloids and 1 flavone were identified by co-chromatography of the sample extract with authentic standards, comparison of the retention time, characteristic molecular ions and fragment ions, or were tentatively identified by MS/MS determination. Moreover, the method was validated for the simultaneous quantification of the 24 components within 10.5 min. The potential chemical markers were identified for classification of the U. species samples by principal component analysis (PCA) and orthogonal partial least squared discriminant analysis (OPLS-DA). The results demonstrate the similarity and differences in alkaloids among the five U. species, which is helpful for the standardization and quality control of the medical materials of the U. Ramulus Cum Unics (URCU). Furthermore, with multivariate statistical analysis, the determined markers are more definite and useful for chemotaxonomy of the U. genus. PMID:25366313

Wang, Hai-Bo; Qi, Wen; Zhang, Lin; Yuan, Dan

2014-01-01

92

Novel, Improved Sample Preparation for Rapid, Direct Identification from Positive Blood Cultures Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry  

PubMed Central

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used for rapid and reliable identification of bacteria and yeast grown on agar plates. Moreover, MALDI-TOF MS also holds promise for bacterial identification from blood culture (BC) broths in hospital laboratories. The most important technical step for the identification of bacteria from positive BCs by MALDI-TOF MS is sample preparation to remove blood cells and host proteins. We present a method for novel, rapid sample preparation using differential lysis of blood cells. We demonstrate the efficacy and ease of use of this sample preparation and subsequent MALDI-TOF MS identification, applying it to a total of 500 aerobic and anaerobic BCs reported to be positive by a Bactec 9240 system. In 86.5% of all BCs, the microorganism species were correctly identified. Moreover, in 18/27 mixed cultures at least one isolate was correctly identified. A novel method that adjusts the score value for MALDI-TOF MS results is proposed, further improving the proportion of correctly identified samples. The results of the present study show that the MALDI-TOF MS-based method allows rapid (<20 minutes) bacterial identification directly from positive BCs and with high accuracy. PMID:21889611

Schubert, Sören; Weinert, Kirsten; Wagner, Chris; Gunzl, Beatrix; Wieser, Andreas; Maier, Thomas; Kostrzewa, Markus

2011-01-01

93

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...

94

Comparison of PCR/Electron spray Ionization-Time-of-Flight-Mass Spectrometry versus Traditional Clinical Microbiology for active surveillance of organisms contaminating high-use surfaces in a burn intensive care unit, an orthopedic ward and healthcare workers  

PubMed Central

Background Understanding nosocomial pathogen transmission is restricted by culture limitations. Novel platforms, such as PCR-based electron spray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS), may be useful as investigational tools. Methods Traditional clinical microbiology (TCM) and PCR/ESI-TOF-MS were used to recover and detect microorganisms from the hands and personal protective equipment of 10 burn intensive care unit (ICU) healthcare workers providing clinical care at a tertiary care military referral hospital. High-use environmental surfaces were assessed in 9 burn ICU and 10 orthopedic patient rooms. Clinical cultures during the study period were reviewed for pathogen comparison with investigational molecular diagnostic methods. Results From 158 samples, 142 organisms were identified by TCM and 718 by PCR/ESI-TOF-MS. The molecular diagnostic method detected more organisms (4.5?±?2.1 vs. 0.9?±?0.8, p?TOF-MS. Gram-negative organisms were less commonly identified than gram-positive by both methods; especially by TCM. Among all detected bacterial species, similar percentages were typical nosocomial pathogens (18-19%) for TCM vs. PCR/ESI-TOF-MS. PCR/ESI-TOF-MS also detected mecA in 112 samples, vanA in 13, and KPC-3 in 2. MecA was associated (p?TOF-MS detected more organisms, especially gram-negatives, compared to TCM, but the current assay format is limited by the number of antibiotic resistance determinants it covers. Further large-scale assessments of PCR/ESI-TOF-MS for hospital surveillance are warranted. PMID:23050585

2012-01-01

95

Direct Identification of Urinary Tract Pathogens from Urine Samples 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 been suggested as a reliable method for bacterial identification from cultures. Direct analysis of clinical samples might increase the usefulness of this method, shortening the time for microorganism identification. We compared conventional methods for the diagnosis of urinary tract infections (UTIs) and identification of the urinary tract pathogens (automated screening, plate cultures, and identification based on biochemical characteristics) and a fast method based on conventional screening and MALDI-TOF MS. For this latter method, 4 ml of urine was centrifuged at a low-revolution setting (2,000 × g) to remove leukocytes and then at high revolutions (15,500 × g) to collect bacteria. The pellet was washed and then applied directly to the MALDI-TOF MS plate. Two hundred sixty urine samples, detected as positive by the screening device (UF-1000i), were processed by culture and MALDI-TOF MS. Twenty samples were positive in the screening device but negative in culture, and all of them were also negative by MALDI-TOF MS. Two-hundred thirty-five samples displayed significant growth of a single morphological type in culture. Two-hundred twenty of them showed bacterial growth of >105 CFU/ml. Microorganism identifications in this group were coincident at the species level in 202 cases (91.8%) and at the genus level in 204 cases (92.7%). The most frequent microorganism was Escherichia coli (173 isolates). MALDI-TOF MS identified this microorganism directly from the urine sample in 163 cases (94.2%). Our results show that MALDI-TOF MS allows bacterial identification directly from infected urine in a short time, with high accuracy, and especially when Gram-negative bacteria with high bacterial counts are involved. PMID:20392910

Ferreira, Laura; Sánchez-Juanes, Fernando; González-Ávila, Magdalena; Cembrero-Fuciños, David; Herrero-Hernández, Ana; González-Buitrago, José Manuel; Muñoz-Bellido, Juan Luis

2010-01-01

96

Determination of genotoxic phenylhydrazine agaritine in mushrooms using liquid chromatography–electrospray ionization tandem mass spectrometry  

Microsoft Academic Search

A new method with good sensitivity and specificity for detecting and quantifying genotoxic hydrazines, agaritine and 4-(hydroxymethyl)phenylhydrazine (HMPH), was developed using liquid chromatography–electrospray tandem mass spectrometry (MS). Synthetic agaritine and HMPH were structurally assigned by H-, C- and two-dimensional nuclear magnetic resonance (NMR) analysis (HMBC and HMQC), high-resolution fast-atom bombardment (HR-FAB) MS and time of flight (TOF) MS. The polar

Kazunari Kondo; Asako Watanabe; Yuko Iwanaga; Ikuro Abe; Hideya Tanaka; Megumi Hamano Nagaoka; Hiroshi Akiyama; Tamio Maitani

2006-01-01

97

Utility of matrix-assisted laser desorption ionization-time of flight mass spectrometry following introduction for routine laboratory bacterial identification.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was evaluated prospectively in a diagnostic laboratory. Nine hundred twenty-seven organisms were tested in triplicate; 2,351/2,781 (85%) species and 2,681/2,781 (96%) genus identifications were correct. Known issues such as the misidentification of alpha-hemolytic streptococci as Streptococcus pneumoniae were easily corrected. Identifications cost AUD$0.45 per isolate and were available in minutes. MALDI-TOF MS is rapid, accurate, and inexpensive. PMID:21632894

Neville, Stephen A; Lecordier, Annabelle; Ziochos, Helen; Chater, Mathew J; Gosbell, Iain B; Maley, Michael W; van Hal, Sebastiaan J

2011-08-01

98

Differentiation of Raoultella ornithinolytica/planticola and Klebsiella oxytoca clinical isolates by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.  

PubMed

Ninety-nine clinical isolates previously identified as Klebsiella oxytoca were evaluated using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Eight isolates were identified as Raoultella spp., being 5 Raoultella spp. and 3 K. oxytoca, by 16S rRNA sequencing. These isolates were correctly identified by applying the 10% differential rule for the MALDI-TOF MS score values. This approach might be useful to discriminate Raoultella species from K. oxytoca. PMID:23375086

de Jong, Eefje; de Jong, Arjan S; Smidts-van den Berg, Nathalie; Rentenaar, Rob J

2013-04-01

99

Graphene as a Novel Matrix for the Analysis of Small Molecules by MALDI-TOF MS  

PubMed Central

Graphene was utilized for the first time as matrix for the analysis of low-molecular weight compounds using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Polar compounds including amino acids, polyamines, anticancer drugs and nucleosides could be successfully analyzed. Additionally, nonpolar compounds including steroids could be detected with high resolution and sensitivity. Compared with conventional matrix, graphene exhibited high desorption/ionization efficiency for nonpolar compounds. The graphene matrix functions as substrate to trap analytes, and it transfers energy to the analytes upon laser irradiation, which allowed for the analytes to be readily desorbed/ionized and interference of intrinsic matrix ions to be eliminated. The use of graphene as matrix avoided the fragmentation of analytes and provided good reproducibility and high salt tolerance, underscoring the potential application of graphene as matrix for MALDI-MS analysis of practical samples in complex sample matrices. We also demonstrated that the use of graphene as adsorbent for the solid-phase extraction of squalene could improve greatly the detection limit. This work not only opens a new field for applications of graphene, but also offers a new technique for high-speed analysis of low-molecular weight compounds in areas such as metabolism research and natural products characterization. PMID:20565059

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

2010-01-01

100

Systematic analyses of free ceramide species and ceramide species comprising neutral glycosphingolipids by MALDI-TOF MS with high-energy CID.  

PubMed

Free ceramides and glycosphingolipids (GSLs) are important components of the membrane microdomain and play significant roles in cell survival. Recent studies have revealed that both fatty acids and long-chain bases (LCBs) are more diverse than expected, in terms of i) alkyl chain length, ii) hydroxylation and iii) the presence or absence of double bonds. Electrospray ionization mass spectrometry and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) have been well utilized to characterize sphingolipids with high throughput, but reports to date have not fully characterized various types of ceramide species such as hydroxyl fatty acids and/or trihydroxy-LCBs of both free ceramides and the constituent ceramides in neutral GSLs. We performed a systematic analysis of both ceramide species, including LCBs with nona-octadeca lengths using MALDI-TOF MS with high-energy collision-induced dissociation (CID) at 20 keV. Using both protonated and sodiated ions, this technique enabled us to propose general rules to discriminate between isomeric and isobaric ceramide species, unrelated to the presence or absence of sugar chains. In addition, this high-energy CID generated (3,5)A ions, indicating Hex 1-4 Hex linkage in the sugar chains. Using this method, we demonstrated distinct differences among ceramide species, including free ceramides, sphingomyelins, and neutral GSLs of glucosylceramides, galactosylceramides, lactosylceramides, globotriaosylceramides and Forssman glycolipids in the equine kidneys. PMID:21400001

Tanaka, Kouji; Yamada, Masaki; Tamiya-Koizumi, Keiko; Kannagi, Reiji; Aoyama, Toshifumi; Hara, Atsushi; Kyogashima, Mamoru

2011-02-01

101

The value of surface enhanced laser desorption/ionization-time of flight mass spectrometry at the diagnosis of non-small cell lung cancer: a systematic review.  

PubMed

Numbers of studies used surface enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF-MS) to find novel serum biomarkers for non-small cell lung cancer (NSCLC). It is arguable whether the SELDI technique has its value of diagnostic accuracy for NSCLC. The purpose of our study is to determine the diagnostic accuracy of SELDI-TOF-MS for diagnosing NSCLC. The Cochrane Central Register of Controlled Trials, MEDLINE, Pub Med, EMBASE, the Chinese Biomedical Literature Database, the China Academic Journals Full-text Database, and the Chinese Scientific Journals Database were searched systematically for potential studies. Reference lists of included studies and review articles were also reviewed. All studies that reported data on patients with a confirmed diagnosis of NSCLC and that compared the measurement of SELDI-TOF-MS with pathology standard were considered for inclusion. 11 studies were included in the systematic review. The ranges of the diagnostic value of SELDI-TOF-MS for NSCLC were as follows: sensitivity (SEN) was 0.70~1.00; specificity (SPE) was 0.68~1.00; positive likelihood ratio (PLR) was 2.23~23.14; negative likelihood ratio (NLR) was 0.04~0.43; and diagnostic odds ratio (DOR) was 5.17~621.0, respectively. SELDI-TOF-MS showed high accuracy in identifying NSCLC, and could be a potential screening tool for diagnosing NSCLC patients. PMID:23862745

Jiang, Feng; Zhou, Xiang-Yu; Huang, Jing

2014-04-01

102

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: a Fundamental Shift in the Routine Practice of Clinical Microbiology  

PubMed Central

SUMMARY 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

2013-01-01

103

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

104

Potential pitfalls in MALDI-TOF MS analysis of abiotically synthesized RNA oligonucleotides.  

PubMed

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. PMID:23793938

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

2013-06-01

105

The Construction and Evaluation of Reference Spectra for the Identification of Human Pathogenic Microorganisms by MALDI-TOF MS  

PubMed Central

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an emerging technique for the rapid and high-throughput identification of microorganisms. There remains a dearth of studies in which a large number of pathogenic microorganisms from a particular country or region are utilized for systematic analyses. In this study, peptide mass reference spectra (PMRS) were constructed and evaluated from numerous human pathogens (a total of 1019 strains from 94 species), including enteric (46 species), respiratory (21 species), zoonotic (17 species), and nosocomial pathogens (10 species), using a MALDI-TOF MS Biotyper system (MBS). The PMRS for 380 strains of 52 species were new contributions to the original reference database (ORD). Compared with the ORD, the new reference database (NRD) allowed for 28.2% (from 71.5% to 99.7%) and 42.3% (from 51.3% to 93.6%) improvements in identification at the genus and species levels, respectively. Misidentification rates were 91.7% and 57.1% lower with the NRD than with the ORD for genus and species identification, respectively. Eight genera and 25 species were misidentified. For genera and species that are challenging to accurately identify, identification results must be manually determined and adjusted in accordance with the database parameters. Through augmentation, the MBS demonstrated a high identification accuracy and specificity for human pathogenic microorganisms. This study sought to provide theoretical guidance for using PMRS databases in various fields, such as clinical diagnosis and treatment, disease control, quality assurance, and food safety inspection. PMID:25181391

Xiao, Di; Ye, Changyun; Zhang, Huifang; Kan, Biao; Lu, Jingxing; Xu, Jianguo; Jiang, Xiugao; Zhao, Fei; You, Yuanhai; Yan, Xiaomei; Wang, Duochun; Hu, Yuan; Zhang, Maojun; Zhang, Jianzhong

2014-01-01

106

The use of multidimensional liquid-phase separations and mass spectrometry for the detailed characterization of posttranslational modifications in glycoproteins.  

PubMed

The goal of characterization of the proteome, while challenging in itself, is further complicated by the microheterogeneity introduced by posttranslational modifications such as glycosylation. A combination of liquid chromatography (LC), capillary electrophoresis (CE), and mass spectrometry (MS) offers the advantages of unique selectivity and high efficiency of the separation methods combined with the mass specificity and sensitivity of MS. In the current work, the combination of liquid-phase separations and mass spectrometry is demonstrated through the on-line coupling of electrospray ionization mass spectrometry (ESI-MS) and off-line coupling with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS). LC/ESI-MS yields real-time results while maintaining the separation obtained from the LC analysis. CE/MALDI TOF-MS offers high-mass detection and extremely low detection limits. The unique separation selectivity of CE relative to reversed-phase HPLC separations of the members of a glycopeptide family was used to develop an integrated multidimensional analysis achieved by the off-line coupling of LC, CE, and MALDI TOF-MS. To demonstrate the applicability of these techniques to the characterization of the heterogeneity of posttranslational modifications present in glycoproteins, we will report on the study of the glycoforms present in a N-linked site in a single-chain plasminogen activator (DSPA?1). PMID:21644704

Udiavar, S; Apffel, A; Chakel, J; Swedberg, S; Hancock, W S; Pungor, E

1998-09-01

107

Detection of Biomarkers of Pathogenic Naegleria fowleri Through Mass Spectrometry and Proteomics.  

PubMed

Emerging methods based on mass spectrometry (MS) can be used in the rapid identification of microorganisms. Thus far, these practical and rapidly evolving methods have mainly been applied to characterize prokaryotes. We applied matrix-assisted laser-desorption-ionization-time-of-flight mass spectrometry MALDI-TOF MS in the analysis of whole cells of 18 N. fowleri isolates belonging to three genotypes. Fourteen originated from the cerebrospinal fluid or brain tissue of primary amoebic meningoencephalitis patients and four originated from water samples of hot springs, rivers, lakes or municipal water supplies. Whole Naegleria trophozoites grown in axenic cultures were washed and mixed with MALDI matrix. Mass spectra were acquired with a 4700 TOF-TOF instrument. MALDI-TOF MS yielded consistent patterns for all isolates examined. Using a combination of novel data processing methods for visual peak comparison, statistical analysis and proteomics database searching we were able to detect several biomarkers that can differentiate all species and isolates studied, along with common biomarkers for all N. fowleri isolates. Naegleria fowleri could be easily separated from other species within the genus Naegleria. A number of peaks detected were tentatively identified. MALDI-TOF MS fingerprinting is a rapid, reproducible, high-throughput alternative method for identifying Naegleria isolates. This method has potential for studying eukaryotic agents. PMID:25231600

Moura, Hercules; Izquierdo, Fernando; Woolfitt, Adrian R; Wagner, Glauber; Pinto, Tatiana; Del Aguila, Carmen; Barr, John R

2015-01-01

108

UPLC/Q-TOF MS-Based Metabolomics and qRT-PCR in Enzyme Gene Screening with Key Role in Triterpenoid Saponin Biosynthesis of Polygala tenuifolia  

PubMed Central

Background The dried root of Polygala tenuifolia, named Radix Polygalae, is a well-known traditional Chinese medicine. Triterpenoid saponins are some of the most important components of Radix Polygalae extracts and are widely studied because of their valuable pharmacological properties. However, the relationship between gene expression and triterpenoid saponin biosynthesis in P. tenuifolia is unclear. Methodology/Findings In this study, ultra-performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (Q-TOF MS)-based metabolomic analysis was performed to identify and quantify the different chemical constituents of the roots, stems, leaves, and seeds of P. tenuifolia. A total of 22 marker compounds (VIP>1) were explored, and significant differences in all 7 triterpenoid saponins among the different tissues were found. We also observed an efficient reference gene GAPDH for different tissues in this plant and determined the expression level of some genes in the triterpenoid saponin biosynthetic pathway. Results showed that MVA pathway has more important functions in the triterpenoid saponin biosynthesis of P. tenuifolia. The expression levels of squalene synthase (SQS), squalene monooxygenase (SQE), and beta-amyrin synthase (?-AS) were highly correlated with the peak area intensity of triterpenoid saponins compared with data from UPLC/Q-TOF MS-based metabolomic analysis. Conclusions/Significance This finding suggested that a combination of UPLC/Q-TOF MS-based metabolomics and gene expression analysis can effectively elucidate the mechanism of triterpenoid saponin biosynthesis and can provide useful information on gene discovery. These findings can serve as a reference for using the overexpression of genes encoding for SQS, SQE, and/or ?-AS to increase the triterpenoid saponin production of P. tenuifolia. PMID:25148032

Li, Zhenyu; Xu, Xiaoshuang; Peng, Bing; Qin, Xuemei; Du, Guanhua

2014-01-01

109

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

2008-09-01

110

Exploring serological classification tree model of active pulmonary tuberculosis by magnetic beads pretreatment and MALDI-TOF MS analysis.  

PubMed

Pulmonary tuberculosis (TB) is an infectious disease disturbing status of public health, and accurate diagnosis of TB would effectively help control the disturbance. Our study tried to establish a classification tree model that distinguished active TB from non-TB individuals. We used matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) combined with weak cationic exchange (WCX) magnetic beads to analyse 178 serum samples containing 75 patients with active TB and 103 non-TB individuals (43 patients with common pulmonary diseases and 60 healthy controls). Samples were randomly divided into a training set and a test set. Statistical softwares were applied to construct this model. An amount of 48 differential expressed peaks (P < 0.05) were identified by the training set, and our model was set up by three of them, m/z 7626, 8561 and 8608. This model can discriminate patients with active TB from patients with non-TB with a sensitivity of 98.3% and a specificity of 84.4%. The test set was used to verify the performance, which demonstrated good sensitivity and specificity: 85.7% and 83.3%, respectively. Differential expressed peaks between smear-positive and smear-negative active TB also have been analysed. It came out that m/z 8561 and 8608 not only acted as vital factors in the pathogenesis of active TB but also played an important role in regulating different active TB status. In conclusion, MALDI-TOF MS combined with WCX magnetic beads was a powerful technology for constructing classification tree model, and the model we built could serve as a potential diagnostic tool for active TB. PMID:21668462

Deng, C; Lin, M; Hu, C; Li, Y; Gao, Y; Cheng, X; Zhang, F; Dong, M; Li, Y

2011-10-01

111

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

112

Development and validation of a LC/TOF MS method for the determination of carboplatin and paclitaxel in nanovesicles.  

PubMed

Carboplatin and paclitaxel co-loaded nanovesicles (CPT-PTX-CLV), a novel intravenous formulation void of cremophor EL, may have significant advantages over conventional carboplatin and paclitaxel formulations with respect to tumor targeting, sustained drug release, reduced toxicity, and synergistic efficacy profiles. The aim of this study was to develop and validate a rapid, specific, sensitive, and reliable liquid chromatography-time of flight-mass spectrometry (LC/TOF MS)-based bioanalytical method for the simultaneous quantification of CPT and PTX in a fetal bovine serum (FBS) vehicle containing the dispersed nanovesicles. The analytes were extracted from FBS by simple protein precipitation, with subsequent separation of CPT and PTX on a Waters HPLC SunFire C18 column at a flow rate of 0.25 ml/min using gradient elution mode. The total analytical time was only 12 min. Detection and quantitation was performed by electrospray ionization (ESI) in the positive ionization mode with selective ion monitoring (SIM) at m/z 310.0152 for CPT and 876.3224 for PTX. The calibration curves were linear over the concentration range of 10-4,000 ng/ml for CPT and 5-2,000 ng/ml for PTX (r (2) ?>?0.99), with the respective lower limit of quantification (LLOQ) at 10 and 5 ng/ml. The intra- and inter-day precision and accuracy of analysis of the quality control samples at low, medium, and high concentration levels were ?13.6 % relative standard deviation (RSD) and ?14.6 % relative errors (RE). The rapid, sensitive, and reproducible LC/TOF MS method may be used to support preclinical and clinical pharmacological studies of the CPT-PTX-CLV administered by injection in animal and human cancer models. PMID:24573580

Mo, Jingxin; Eggers, Paul K; Raston, Colin L; Lim, Lee Yong

2014-04-01

113

The rapid identification of intact microorganisms using mass spectrometry.  

PubMed

Antibiotic-resistant strains of bacteria continue to emerge, increasing the need for their fast and accurate identification. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS), has become a prominent technique in biological mass spectrometry. We report the application of MALDI-TOF-MS for the identification of intact Gram-negative and Gram-positive microorganisms taken directly from culture. Analysis of bacteria from a single colony is possible, allowing the screening of mixed cultures. Sample preparation is simple and the analysis automated, providing spectra within minutes. The spectra obtained allow identification of microorganisms from different genera, different species, and from different strains of the same species. The procedure provides a unique mass spectral fingerprint of the microorganism, produced from desorbed components of the cell wall. Consistent data were obtained from subcultures grown for 3-day and 6-day periods, from the same cultures 1 day later and from fresh subcultures 2 months later. PMID:9634826

Claydon, M A; Davey, S N; Edwards-Jones, V; Gordon, D B

1996-11-01

114

Rapid identification of bacterial isolates from wheat roots by high resolution whole cell MALDI-TOF MS analysis.  

PubMed

Whole-cell mass spectrometry analysis is a powerful tool to rapidly identify microorganisms. Several studies reported the successful application of this technique to identify a variety of bacterial species with a discriminatory power at the strain level, mainly for bacteria of clinical importance. In this study we used matrix-assisted laser desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) to assess the diversity of wheat-associated bacterial isolates. Wheat plants cultivated in non-sterile vermiculite, under greenhouse conditions were used for bacterial isolation. Total cellular extracts of 138 isolates were analyzed by MALDI-TOF MS and the mass spectra were used to cluster the isolates. Taxonomic identification and phylogenetic reconstruction based on 16S rRNA gene sequences showed the presence of Pseudomonas, Pantoea, Acinetobacter, Enterobacter and Curtobacterium. The 16S rRNA gene sequence analyses were congruent with the clusterization from mass spectra profile. Moreover, MALDI-TOF whole cell mass profiling allowed a finer discrimination of the isolates, suggesting that this technique has the potential of differentiating bacterial isolates at the strain level. PMID:23591594

Stets, Maria Isabel; Pinto, Artur Soares; Huergo, Luciano Fernandes; de Souza, Emanuel Maltempi; Guimarães, Vandeir Francisco; Alves, Alexessander Couto; Steffens, Maria Berenice Reynaud; Monteiro, Rose Adele; Pedrosa, Fábio de Oliveira; Cruz, Leonardo Magalhães

2013-06-10

115

Micro-scale strategy to detect spermine and spermidine by MALDI-TOF MS in foods and identification of apoptosis-related proteins by nano-flow UPLC-MS/MS after treatment with spermine and spermidine.  

PubMed

Spermine and spermidine are multiple-nitrogen compounds found in many foods. Both compounds are essential for cell growth and human health. This study established a simple and fast method of detecting spermine and spermidine in food samples by matrix-assisted laser desorption/ionization combined with time-of-flight mass spectrometry (MALDI-TOF MS). After a simple sample preparation procedure, spermine and spermidine were directly detected by MALDI-TOF MS with no additional purification procedure. The calibration curves for spermine and spermidine ranged from 0.1 to 10?g/mL. In intra- and inter-batch assays of three different concentrations of spermine and spermidine, all relative standard deviations and relative errors were below 18.9%. These experimental results confirmed the practicability and effectiveness of the proposed MALDI-TOF MS method for fast determination of spermine and spermidine in food samples. Furthermore, since spermine and spermidine have important roles in apoptosis, up-regulation and down-regulation of spermine and spermidine during apoptosis were analyzed. After treating NRK-52E cells with spermine and spermidine, the cells were lysed, and cell proteins were collected, and digested. Apoptosis-related proteins were then identified by tandem MS. PMID:25541472

Su, Huai-Hsin; Chuang, Lea-Yea; Tseng, Wei-Lung; Lu, Chi-Yu

2015-01-26

116

VibrioBase: A MALDI-TOF MS database for fast identification of Vibrio spp. that are potentially pathogenic in humans.  

PubMed

Mesophilic marine bacteria of the family Vibrionaceae, specifically V. cholerae, V. parahaemolyticus and V. vulnificus, are considered to cause severe illness in humans. Due to climate-change-driven temperature increases, higher Vibrio abundances and infections are predicted for Northern Europe, which in turn necessitates environmental surveillance programs to evaluate this risk. We propose that whole-cell matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling is a promising tool for the fast and reliable species classification of environmental isolates. Because the reference database does not contain sufficient Vibrio spectra we generated the VibrioBase database in this study. Mass spectrometric data were generated from 997 largely environmental strains and filed in this new database. MALDI-TOF MS clusters were assigned based on the species classification obtained by analysis of partial rpoB (RNA polymerase beta-subunit) sequences. The affiliation of strains to species-specific clusters was consistent in 97% of all cases using both approaches, and the extended VibrioBase generated more specific species identifications with higher matching scores compared to the commercially available database. Therefore, we have made the VibrioBase database freely accessible, which paves the way for detailed risk assessment studies of potentially pathogenic Vibrio spp. from marine environments. PMID:25466918

Erler, René; Wichels, Antje; Heinemeyer, Ernst-August; Hauk, Gerhard; Hippelein, Martin; Reyes, Nadja Torres; Gerdts, Gunnar

2014-11-01

117

A metabolomic protocol for plant systematics by matrix-assisted laser-desorption/ionization time-of flight mass spectrometry.  

PubMed

Matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF MS) has been widely used for the identification and classification of microorganisms based on their proteomic fingerprints. However, the use of MALDI-TOF MS in plant research has been very limited. In the present study, a first protocol is proposed for metabolic fingerprinting by MALDI-TOF MS using three different MALDI matrices with subsequent multivariate data analysis by in-house algorithms implemented in the R environment for the taxonomic classification of plants from different genera, families and orders. By merging the data acquired with different matrices, different ionization modes and using careful algorithms and parameter selection, we demonstrate that a close taxonomic classification can be achieved based on plant metabolic fingerprints, with 92% similarity to the taxonomic classifications found in literature. The present work therefore highlights the great potential of applying MALDI-TOF MS for the taxonomic classification of plants and, furthermore, provides a preliminary foundation for future research. PMID:25622605

Ernst, Madeleine; Silva, Denise B; Silva, Ricardo; Monge, Marcelo; Semir, João; Vêncio, Ricardo Z N; Lopes, Norberto P

2015-02-15

118

Derivatization of organophosphorus nerve agent degradation products for gas chromatography with ICPMS and TOF-MS detection.  

PubMed

Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products by gas chromatography with inductively coupled plasma mass spectrometry (GC-ICPMS) is described. The nonvolatile alkyl phosphonic acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid (IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA, RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC-time of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation products by GC-ICPMS. PMID:17356819

Richardson, Douglas D; Caruso, Joseph A

2007-06-01

119

[UPLC-TOF/MS based chemical profiling approach to evaluate toxicity-attenuated chemical composition in combination of ginseng and radix aconiti praeparata].  

PubMed

In the present study, an ultra performance liquid chromatography coupled with time-of-fight mass spectrometry (UPLC-TOF/MS) based chemical profiling approach was used to evaluate chemical constitution between co-decoction and mixed decoction of ginseng and Radix Aconiti Praeparata. Two different kinds of decoctions, namely co-decoction of ginseng and Radix Aconiti Praeparata: water extract of mixed two herbs, and mixed decoction of ginseng and Radix Aconiti Praeparata: mixed water extract of each individual herbs, were prepared. Batches of these two kinds of decoction samples were subjected to UPLC-TOF/MS analysis. The datasets of t(R) m/z pairs, ion intensities and sample codes were processed with supervised partial least squared discriminant analysis (OPLS-DA) to holistically compare the difference between these two decoction samples. Significant difference between the two decoction samples was showed in the results of positive ion mode. The contents of hypaconitine and deoxyaconitine decreased, while that of benzoylmesaconine, benzoylhypaconine and dehydrated benzoylmesaconine increased in the samples of co-decoction of ginseng and Radix Aconiti Praeparata. The content of diester-diterpenoid alkaloids decreased, while that of monoester-diterpenoid alkaloids increased, which is probably the basis of toxicity-attenuated action when combined ginseng with Radix Aconiti Praeparata. PMID:22375424

Ma, Zeng-Chun; Zhou, Si-Si; Liang, Qian-De; Huo, Chao; Wang, Yu-Guang; Tan, Hong-Ling; Xiao, Cheng-Rong; Gao, Yue

2011-12-01

120

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

2012-12-01

121

Antioxidant Activity of Leaf Extracts from Different Hibiscus sabdariffa Accessions and Simultaneous Determination Five Major Antioxidant Compounds by LC-Q-TOF-MS.  

PubMed

Hibiscus sabdariffa has gained attention for its antioxidant activity. There are many accessions of H. sabdariffa in the world. However, information on the quantification of antioxidant compounds in different accessions is rather limited. In this paper, a liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC-Q-TOF-MS) method for simultaneous determination of five antioxidant compounds (neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, rutin, and isoquercitrin) in H. sabdariffa leaves was developed. The method was validated for linearity, sensitivity, precision, repeatability and accuracy. The validated method has been successfully applied for determination of the five analytes in eight accessions of H. sabdariffa. The eight accessions of H. sabdariffa were evaluated for their antioxidant activities by DPPH free radical scavenging assay. The investigated accessions of H. sabdariffa were rich in rutin and exhibited strong antioxidant activity. The two accessions showing the highest antioxidant activities were from Cuba (No. 2) and Taiwan (No. 5). The results indicated that H. sabdariffa leaves could be considered as a potential antioxidant source for the food industry. The developed LC-Q-TOF-MS method is helpful for quality control of H. sabdariffa. PMID:25525823

Wang, Jin; Cao, Xianshuang; Jiang, Hao; Qi, Yadong; Chin, Kit L; Yue, Yongde

2014-01-01

122

Development and Validation of an In-House Database for Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry-Based Yeast Identification Using a Fast Protein Extraction Procedure  

PubMed Central

In recent studies evaluating the usefulness of the matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based identification of yeasts for the routine diagnosis of fungal infections, preanalytical sample processing has emerged as a critical step for reliable MALDI-TOF MS outcomes, especially when the Bruker Daltonics Biotyper software was used. In addition, inadequate results often occurred due to discrepancies between the methods used for clinical testing and database construction. Therefore, we created an in-house MALDI-TOF MS library using the spectra from 156 reference and clinical yeast isolates (48 species in 11 genera), which were generated with a fast sample preparation procedure. After a retrospective validation study, our database was evaluated on 4,232 yeasts routinely isolated during a 6-month period and fast prepared for MALDI-TOF MS analysis. Thus, 4,209 (99.5%) of the isolates were successfully identified to the species level (with scores of ?2.0), with 1,676 (39.6%) having scores of >2.3. For the remaining 23 (0.5%) isolates, no reliable identification (with scores of <1.7) was obtained. Interestingly, these isolates were almost always from species uniquely represented or not included in the database. As the MALDI-TOF MS results were, except for 23 isolates, validated without additional phenotypic or molecular tests, our proposed strategy can enhance the rapidity and accuracy of MALDI-TOF MS in identifying medically important yeast species. However, while continuous updating of our database will be necessary to enrich it with more strains/species of new and emerging yeasts, the present in-house MALDI-TOF MS library can be made publicly available for future multicenter studies. PMID:24554755

De Carolis, Elena; Vella, Antonietta; Vaccaro, Luisa; Torelli, Riccardo; Posteraro, Patrizia; Ricciardi, Walter; Posteraro, Brunella

2014-01-01

123

Analysis of sucralose and other sweeteners in water and beverage samples by liquid chromatography\\/time-of-flight mass spectrometry  

Microsoft Academic Search

A methodology for the chromatographic separation and analysis of three of the most popular artificial sweeteners (aspartame, saccharin, and sucralose) in water and beverage samples was developed using liquid chromatography\\/time-of-flight mass spectrometry (LC\\/TOF-MS). The sweeteners were extracted from water samples using solid-phase extraction (SPE) cartridges. Furthermore, several beverages were analyzed by a rapid and simple method without SPE, and the

Imma Ferrer; E. Michael Thurman

2010-01-01

124

It's a MALDI but it's a goodie: MALDI-TOF mass spectrometry for microbial identification.  

PubMed

The last few years have witnessed a revolution in the diagnostic microbiology laboratory with the emergence of matrix assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) as an indispensible tool in microbial identification. In many laboratories this has superseded biochemical profiling. A mass spectrum is acquired from an unknown micro-organism and this proteomic fingerprint is then compared with a database of reference spectra to ascertain the likely genus and species identity. The reproducibility of this method is facilitated by the analysis of continually produced, highly abundant proteins (mainly ribosomal proteins) in the mass range 2000 to 20?000?Da. MALDI-TOF MS is reliable and rapid and has the ability to determine the identity of an isolate from culture in a matter of minutes rather than the hours or days required by more traditional methods. In addition to microbial identification of cultured isolates, work is underway to extend the utility of MALDI-TOF MS to include bacterial identification directly from clinical samples as well as providing timely information regarding antibiotic resistance and typing of different micro-organisms. PMID:24781219

Randell, Paul

2014-08-01

125

Identification and Subtyping of Clinically Relevant Human and Ruminant Mycoplasmas 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) 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

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

2013-01-01

126

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 Central

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.

2013-01-01

127

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

2013-02-27

128

Characterization of Bacteria in Ballast Water Using MALDI-TOF Mass Spectrometry  

PubMed Central

To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Since International Maritime Organization (IMO) regulations are concerned with the unintended transportation of pathogenic bacteria through ballast water, emphasis was placed on detecting species of Vibrio, enterococci and coliforms. Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated. At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing. No pathogenic species were detected either by 16S rRNA gene analysis or by MALDI-TOF MS except for the opportunistically pathogenic bacterium Pseudomonas aeruginosa. In addition, in house software that calculated the correlation coefficient values (CCV) of the mass spectral raw data and their variation was developed and used to allow the rapid and efficient identification of marine bacteria in ballast water for the first time. PMID:22685576

Emami, Kaveh; Askari, Vahid; Ullrich, Matthias; Mohinudeen, Khwajah; Anil, Arga Chandrashekar; Khandeparker, Lidita; Burgess, J. Grant; Mesbahi, Ehsan

2012-01-01

129

Quantification of sterol lipids in plants by quadrupole time-of-flight mass spectrometry.  

PubMed

Glycerolipids, sphingolipids, and sterol lipids constitute the major lipid classes in plants. Sterol lipids are composed of free and conjugated sterols, i.e., sterol esters, sterol glycosides, and acylated sterol glycosides. Sterol lipids play crucial roles during adaption to abiotic stresses and plant-pathogen interactions. Presently, no comprehensive method for sterol lipid quantification in plants is available. We used nanospray ionization quadrupole-time-of-flight mass spectrometry (Q-TOF MS) to resolve and identify the molecular species of all four sterol lipid classes from Arabidopsis thaliana. Free sterols were derivatized with chlorobetainyl chloride. Sterol esters, sterol glycosides, and acylated sterol glycosides were ionized as ammonium adducts. Quantification of molecular species was achieved in the positive mode after fragmentation in the presence of internal standards. The amounts of sterol lipids quantified by Q-TOF MS/MS were validated by comparison with results obtained with TLC/GC. Quantification of sterol lipids from leaves and roots of phosphate-deprived A. thaliana plants revealed changes in the amounts and molecular species composition. The Q-TOF method is far more sensitive than GC or HPLC. Therefore, Q-TOF MS/MS provides a comprehensive strategy for sterol lipid quantification that can be adapted to other tandem mass spectrometers. PMID:21382968

Wewer, Vera; Dombrink, Isabel; vom Dorp, Katharina; Dörmann, Peter

2011-05-01

130

Utilization of matrix-assisted laser desorption and ionization time-of-flight mass spectrometry for identification of infantile seborrheic dermatitis-causing Malassezia and incidence of culture-based cutaneous Malassezia microbiota of 1-month-old infants.  

PubMed

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been utilized for identification of various microorganisms. Malassezia species, including Malassezia restricta, which is associated with seborrheic dermatitis, has been difficult to identify by traditional means. This study was performed to develop a system for identification of Malassezia species with MALDI-TOF-MS and to investigate the incidence and variety of cutaneous Malassezia microbiota of 1-month-old infants using this technique. A Malassezia species-specific MALDI-TOF-MS database was developed from eight standard strains, and the availability of this system was assessed using 54 clinical strains isolated from the skin of 1-month-old infants. Clinical isolates were cultured initially on CHROMagar Malassezia growth medium, and the 28S ribosomal DNA (D1/D2) sequence was analyzed for confirmatory identification. Using this database, we detected and analyzed Malassezia species in 68% and 44% of infants with and without infantile seborrheic dermatitis, respectively. The results of MALDI-TOF-MS analysis were consistent with those of rDNA sequencing identification (100% accuracy rate). To our knowledge, this is the first report of a MALDI-TOF-MS database for major skin pathogenic Malassezia species. This system is an easy, rapid and reliable method for identification of Malassezia. PMID:24387229

Yamamoto, Mikachi; Umeda, Yoshiko; Yo, Ayaka; Yamaura, Mariko; Makimura, Koichi

2014-02-01

131

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

2013-02-01

132

The simultaneous determination of hydrophobicity and dissociation constant by liquid chromatography-mass spectrometry.  

PubMed

Convenient methods for testing drug candidates' lipophilicity and acidity are highly requested in modern pharmaceutical research and drug development strategies. Reversed-phase high-performance liquid chromatography (RP HPLC) might be particularly useful for the determination of both dissociation constant and the (pH-dependent) partition coefficient related parameters, applicable in high-throughput analysis of multi-component mixtures. The general theory of combined pH/organic modifier gradient has recently provided equations relating gradient retention time and pH of the mobile phase. The purpose of this work was to facilitate the identification of analytes in this technique by its transfer to RP HPLC coupled with time-of-flight mass spectrometry with electrospray ionization source (ESI-TOF-MS). The accuracy of the proposed methodology was assessed by analyzing a set of known drugs. The ammonium formate, ammonium acetate or ammonium bicarbonate buffers were used to control pH during chromatographic analysis. In result, the pKa and hydrophobicity parameters were determined and the accuracy of the estimated values was assessed by comparing them with literature data. The gradient RP HPLC coupled with ESI-TOF-MS methods allowed for the rapid determination of dissociation constant and hydrophobicity and was shown to be especially applicable for complex mixtures. The use of ESI-TOF-MS detection allowed to achieve the medium-throughput screening rate (100 compounds/day) and provided a simple approach to assess pharmacokinetically important physicochemical properties of drugs. PMID:24598171

Wiczling, P; Struck-Lewicka, W; Kubik, L; Siluk, D; Markuszewski, M J; Kaliszan, R

2014-06-01

133

Rapid laboratory diagnosis for respiratory infectious diseases by using MALDI-TOF mass spectrometry  

PubMed Central

It is still challenging to prevent and treat respiratory infectious diseases. One critical step in the successful treatment of respiratory infections is rapid diagnosis by identifying the causative microorganisms in a timely fashion. However, traditional methods for identification of causative agents could not satisfy the need for rapid and accurate testing due to the limitations of technology-used. In recent years, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) has been validated and used for rapid identification of microorganism and for potential discovery of diseases associated biomarkers. We reviewed recent advances of MALDI-TOF-MS as the laboratory diagnostic tool for the rapid laboratory diagnosis of microorganisms associated with respiratory infectious diseases, with the focus on rapid identification of pathogenic bacteria and molecular markers discovery using MALDI-TOF-MS. With the advanced technologies such as MALDI-TOF, early and targeted therapies based on rapid identification of pathogens and could lead to quick and effective treatment of respiratory infections and better patient management. PMID:24822111

Fu, Jianfeng

2014-01-01

134

Characterisation of the aerobic bacterial flora of boid snakes: application of MALDI-TOF mass spectrometry.  

PubMed

The aim of this study was to identify aerobic bacterial isolates from the respiratory tract of boids with matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS). From 47 boid snakes, swabs from the oral cavity, tracheal wash samples and, in cases in which postmortem examination was performed, pulmonary tissue samples were taken. Each snake was classified as having inflammation of the respiratory tract and/or oral cavity, or without evidence of inflammation based on combination of clinical, cytological and histopathological findings. Samples collected from the respiratory tract and oral cavity were inoculated onto routine media and bacteria were cultured aerobically. All morphologically distinct individual colonies obtained were analysed using MALDI-TOF MS. Unidentified isolates detected in more than three snakes were selected for further 16S rDNA PCR and sequencing. Among all examined isolates (n=243), 49 per cent (n=119) could be sufficiently speciated using MALDI-TOF MS. Molecular biology revealed several bacterial species that have not been previously described in reptiles. With an average of 6.3 different isolates from the respiratory tract and/or oral cavity, boids with inflammatory disease harboured significantly more bacterial species than boids without inflammatory disease (average 2.8 isolates). PMID:25487809

Plenz, Bastian; Schmidt, Volker; Grosse-Herrenthey, Anke; Krüger, Monika; Pees, Michael

2014-12-01

135

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

136

[Fingerprint analysis of Fritillaria thunbergii using rapid resolution liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry].  

PubMed

A fingerprint method for quality assessment of Fritillaria thunbergii was developed by rapid resolution liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (RRLC-Q-TOF-MS). The separation was performed using Agilent Eclipse Plus C18 column (2.1 mm x 100 mm, 1.8 microm) by gradient elution with acetonitrile and 0.1% formic acid aqueous solution (containing 10 mmol x L(-1) ammonium formate) as the mobile phase. Q-TOF-MS was used to obtain the accurate mass for precursor and product ions. Under this chromatographic and MS condition, 12 batches of F. thunbergii and its adulterants (F. hupehensis and F. pallidiflora) were analyzed by RRLC-Q-TOF-MS. Fifteen steroidal alkaloids were identified from F. thunbergii, F. hupehensis and F. pallidiflora and nine were assigned as the common characteristic peaks for F. thunbergii. The RRLC-Q-TOF-MS fingerprint of F. thunbergii was different significantly with those of F. hupehensis and F. pallidiflora. The quality of 12 batches of F. thunbergii samples were finally evaluated by hierarchical clustering analysis (HCA) and principle component analysis (PCA). This convenient and high specific method could be used to identify and evaluate the quality of the F. thunbergii. PMID:24380306

Zhou, Jian-Liang; Liu, Wei; Guo, Zeng-Xi; Chen, Bi-Lian

2013-09-01

137

Identification of medically relevant species of arthroconidial yeasts 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) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories. PMID:23678074

Kolecka, Anna; Khayhan, Kantarawee; Groenewald, Marizeth; Theelen, Bart; Arabatzis, Michael; Velegraki, Aristea; Kostrzewa, Markus; Mares, Mihai; Taj-Aldeen, Saad J; Boekhout, Teun

2013-08-01

138

Identification of Medically Relevant Species of Arthroconidial Yeasts 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) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories. PMID:23678074

Kolecka, Anna; Khayhan, Kantarawee; Groenewald, Marizeth; Theelen, Bart; Arabatzis, Michael; Velegraki, Aristea; Kostrzewa, Markus; Mares, Mihai; Taj-Aldeen, Saad J.

2013-01-01

139

A Sensitive and Effective Proteomic Approach to Identify She-Donkey’s and Goat’s Milk Adulterations by MALDI-TOF MS Fingerprinting  

PubMed Central

She-donkey’s milk (DM) and goat’s milk (GM) are commonly used in newborn and infant feeding because they are less allergenic than other milk types. It is, therefore, mandatory to avoid adulteration and contamination by other milk allergens, developing fast and efficient analytical methods to assess the authenticity of these precious nutrients. In this experimental work, a sensitive and robust matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling was designed to assess the genuineness of DM and GM milks. This workflow allows the identification of DM and GM adulteration at levels of 0.5%, thus, representing a sensitive tool for milk adulteration analysis, if compared with other laborious and time-consuming analytical procedures. PMID:25110863

Di Girolamo, Francesco; Masotti, Andrea; Salvatori, Guglielmo; Scapaticci, Margherita; Muraca, Maurizio; Putignani, Lorenza

2014-01-01

140

A sensitive and effective proteomic approach to identify she-donkey's and goat's milk adulterations by MALDI-TOF MS fingerprinting.  

PubMed

She-donkey's milk (DM) and goat's milk (GM) are commonly used in newborn and infant feeding because they are less allergenic than other milk types. It is, therefore, mandatory to avoid adulteration and contamination by other milk allergens, developing fast and efficient analytical methods to assess the authenticity of these precious nutrients. In this experimental work, a sensitive and robust matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling was designed to assess the genuineness of DM and GM milks. This workflow allows the identification of DM and GM adulteration at levels of 0.5%, thus, representing a sensitive tool for milk adulteration analysis, if compared with other laborious and time-consuming analytical procedures. PMID:25110863

Di Girolamo, Francesco; Masotti, Andrea; Salvatori, Guglielmo; Scapaticci, Margherita; Muraca, Maurizio; Putignani, Lorenza

2014-01-01

141

Interlaboratory comparison of intact-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry results for identification and differentiation of Brucella spp.  

PubMed

Classical microbiological diagnosis of human brucellosis is time-consuming, hazardous, and subject to variable interpretation. Intact-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the routine identification of Brucella spp. Analysis of mass peak patterns allowed accurate identification to the genus level. However, statistical models based on peak intensities were needed for definite species differentiation. Interlaboratory comparison confirmed the reproducibility of the results. PMID:23850950

Karger, Axel; Melzer, Falk; Timke, Markus; Bettin, Barbara; Kostrzewa, Markus; Nöckler, Karsten; Hohmann, Angelika; Tomaso, Herbert; Neubauer, Heinrich; Al Dahouk, Sascha

2013-09-01

142

Interlaboratory Comparison of Intact-Cell Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Results for Identification and Differentiation of Brucella spp.  

PubMed Central

Classical microbiological diagnosis of human brucellosis is time-consuming, hazardous, and subject to variable interpretation. Intact-cell matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the routine identification of Brucella spp. Analysis of mass peak patterns allowed accurate identification to the genus level. However, statistical models based on peak intensities were needed for definite species differentiation. Interlaboratory comparison confirmed the reproducibility of the results. PMID:23850950

Karger, Axel; Melzer, Falk; Timke, Markus; Bettin, Barbara; Kostrzewa, Markus; Nöckler, Karsten; Hohmann, Angelika; Tomaso, Herbert; Neubauer, Heinrich

2013-01-01

143

[Characterization of aromatic hydrocarbons in heavy gas oil using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry].  

PubMed

An analytical method for separating and identifying the aromatic hydrocarbons in heavy gas oil using comprehensive two-dimensional gas chromatography (GC x GC) coupled to time-of-flight mass spectrometry (TOF MS) was established. The two-dimensional distribution by ring number of the aromatic hydrocarbons was obtained. Besides phenanthrene and methyl-phenanthrene, many other polycyclic aromatic hydrocarbons (PAHs) such as pyrene and benzo [a] anthracene were identified by using the retention times, standard mass spectra or literature reports. The method was successfully applied to the hydrotreating process of heavy gas oil and the hydrotreated products of phenanthrene, pyrene were identified. This method provided technical support for the characterization of aromatic hydrocarbons in heavy gas oil and the investigation of hydrogenation mechanism of polycyclic aromatic hydrocarbons. Compared with the conventional method, gas chromatography coupled to mass spectrometry (GC-MS), the GC x GC-TOF MS method illustrated the obvious advantages for heavy gas oil analysis. PMID:22679825

Guo, Kun; Zhou, Jian; Liu, Zelong

2012-02-01

144

The comparative research on constituents of Radix Aconiti and its processing by HPLC quadrupole TOF-MS.  

PubMed

Based upon the regulations stipulated by the State Food and Drug Administration of China, only the processed, detoxified tubers and roots of Aconitum are allowed to be administered orally, used in clinical decoctions and adopted as raw materials for pharmaceutical manufacturing, so the processing principle of preparation of Radix Aconiti is important for ensuring the Radix Aconiti praeparata quality. A simple approach was described for HPLC-Q-TOF-MS screening and identification of many of the aconitine alkaloids present in unprocessed Radix Aconiti and Radix Aconiti praeparata. To compare their fingerprints, the processing principle of preparation of Radix Aconiti was developed. Twenty-nine compounds and 26 compounds were assigned to aconitine alkaloids and tentatively identified by comparing accurate mass and fragments information with that of the authentic standards or by mass spectrometry analysis and retrieving the reference literature. The nonester alkaloids were almost the same. The diester diterpene alkaloids were decreased, the monoester-diterpene alkaloids were increased and lipo-alkaloids decreased obviously in the processing of the preparation. These transformed components could be regarded as potential chemical markers that can be used to distinguish between raw and processed herbs. PMID:22311596

Wu, Jian; Hong, Bo; Wang, Jia; Wang, Xi; Niu, Sijia; Zhao, Chunjie

2012-11-01

145

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

2013-05-15

146

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

147

Hybrid Ion-Detector/Data-Acquisition System for a TOF-MS  

NASA Technical Reports Server (NTRS)

A modified ion-detector/data-acquisition system has been devised to increase the dynamic range of a time-of-flight mass spectrometer (TOF-MS) that, previously, included a microchannel-plate detector and a data-acquisition system based on counting pulses and time-tagging them by use of a time-to-digital converter (TDC). The dynamic range of the TOF-MS was limited by saturation of the microchannel plate detector, which can handle no more than a few million counts per second. The modified system includes (1) a combined microchannel plate/discrete ion multiplier and (2) a hybrid data-acquisition system that simultaneously performs analog current or voltage measurements and multianode single-ion-pulse-counting time-of-flight measurements to extend the dynamic range of a TDC into the regime in which a mass peak comprises multiple ions arriving simultaneously at the detector. The multianode data are used to determine, in real time, whether the detector is saturated. When saturation is detected, the data-acquisition system selectively enables circuitry that simultaneously determines the ion-peak intensity by measuring the time profile of the analog current or voltage detector-output signal.

Burton, William D., Jr.; Schultz, J. Albert; Vaughn, Valentine; McCully, Michael; Ulrich, Steven; Egan, Thomas F.

2006-01-01

148

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

149

Identification of Lactobacillus from the Saliva of Adult Patients with Caries Using Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry  

PubMed Central

Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) has been presented as a superior method for the detection of microorganisms in body fluid samples (e.g., blood, saliva, pus, etc.) However, the performance of MALDI-TOF MS in routine identification of caries-related Lactobacillus isolates from saliva of adult patients with caries has not been determined. In the present study, we introduced a new MALDI-TOF MS system for identification of lactobacilli. Saliva samples were collected from 120 subjects with caries. Bacteria were isolated and cultured, and each isolate was identified by both 16S rRNA sequencing and MALDI-TOF MS. The identification results obtained by MALDI-TOF MS were concordant at the genus level with those of conventional 16S rRNA-based sequencing for 88.6% of lactobacilli (62/70) and 95.5% of non-lactobacilli (21/22). Up to 96 results could be obtained in parallel on a single MALDI target, suggesting that this is a reliable high-throughput approach for routine identification of lactobacilli. However, additional reference strains are necessary to increase the sensitivity and specificity of species-level identification. PMID:25166027

Ma, Qingwei; Song, Yeqing; Zhang, Qian; Wang, Xiaoyan; Chen, Feng

2014-01-01

150

2,3,4,5-Tetrakis(3',4'-dihydroxylphenyl)thiophene: a new matrix for the selective analysis of low molecular weight amines and direct determination of creatinine in urine by MALDI-TOF MS.  

PubMed

Small organic matrixes are still the most commonly used ones in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) because of their advantages of high sensitivity, convenience, and cost-effectiveness. However, due to the matrix interference in the low mass region, the direct analysis of low molecular weight amines in complex surroundings with conventional organic matrixes remains a challenge. Here, a new Brønsted-Lowry acid compound 2,3,4,5-tetrakis(3',4'-dihydroxylphenyl)thiophene (DHPT) was designed, synthesized, and applied as a matrix for analysis of low molecular weight amines by MALDI-TOF MS. DHPT displays good selectivity in the analysis of amines without matrix-related interference and the low picomole/femtomole limit-of-detection was obtained in positive ion mode. With DHPT, the metabolites including creatinine, glycine, alloxan, allantoin, and 3-hydroxyhippuric acid in human urine were directly analyzed by MALDI-TOF MS. The identity of these metabolites was confirmed by tandem mass spectrometry. Furthermore, the urine creatinine was quantitatively determined using isotope-labeled internal standard. This DHPT-assisted LDI MS method provides a general approach for both qualitative and quantitative analysis of low molecular weight amines. PMID:23113720

Chen, Suming; Chen, Li; Wang, Jianing; Hou, Jian; He, Qing; Liu, Jian'an; Wang, Jiyun; Xiong, Shaoxiang; Yang, Guoqiang; Nie, Zongxiu

2012-12-01

151

MALDI-TOF MS analysis of cellodextrins and xylo-oligosaccharides produced by hindgut homogenates of Reticulitermes santonensis.  

PubMed

Hindgut homogenates of the termite Reticulitermes santonensis were incubated with carboxymethyl cellulose (CMC), crystalline celluloses or xylan substrates. Hydrolysates were analyzed with matrix-assisted laser desorption/ionization coupled to time-of-flight mass spectrometry (MALDI-TOF MS). The method was first set up using acid hydrolysis analysis to characterize non-enzymatic profiles. Commercial enzymes of Trichoderma reesei or T. longibrachiatum were also tested to validate the enzymatic hydrolysis analysis. For CMC hydrolysis, data processing and visual display were optimized to obtain comprehensive profiles and allow rapid comparison and evaluation of enzymatic selectivity, according to the number of substituents of each hydrolysis product. Oligosaccharides with degrees of polymerization (DPs) ranging from three to 12 were measured from CMC and the enzymatic selectivity was demonstrated. Neutral and acidic xylo-oligosaccharides with DPs ranging from three to 11 were measured from xylan substrate. These results are of interest for lignocellulose biomass valorization and demonstrated the potential of termites and their symbiotic microbiota as a source of interesting enzymes for oligosaccharides production. PMID:24731986

Brasseur, Catherine; Bauwens, Julien; Tarayre, Cédric; Mattéotti, Christel; Thonart, Philippe; Destain, Jacqueline; Francis, Frédéric; Haubruge, Eric; Portetelle, Daniel; Vandenbol, Micheline; Focant, Jean-François; De Pauw, Edwin

2014-01-01

152

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

NASA Astrophysics Data System (ADS)

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 ([alpha]-cyano-4-hydroxycinnamic acid, CHCA), followed by high-energy CID using "cold" matrices (2,5-dihydroxybenzoic acid, DHB; 2,6-dihydroxyacetophenone/di-ammonium hydrogen citrate, DHAP/DAHC). This strategy ensures that PSD results in a rich variety of product ions derived from charge-driven processes that provide gross structural information. High-energy CID (20 keV collision energy range) of low internal energy [M + H]+ ions is then employed to reveal complementary side-chain detail (i.e. Leu/Ile distinction) in a manner highly selective for charge remote fragmentation (CRF), because PSD is largely reduced. As expected from the known behaviour of protonated peptides at 10 keV collision energies, charge fixation at basic sites required for CRF is more pronounced in CID than in PSD. We have obtained spectra for a synthetic peptide that approximate the results and performance of MALDI high-energy CID obtained on sector-based instrumentation (EBE-oa-TOF).

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

1997-12-01

153

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

154

PTR-TOF-MS measurements of atmospheric VOCs during the CALNEX 2010 campaign  

NASA Astrophysics Data System (ADS)

During the CALNEX 2010 study, in-situ volatile organic compounds (VOCs) measurements were made aboard the WHOI research vessel Atlantis by a high resolution proton transfer mass spectrometer (PTR-TOF-MS, Ionicon Analytik). The PTR-TOF-MS was deployed along with a GC-FID system during cruise along the California coast and inside port areas to characterize atmospheric levels and chemical transformation of the extensive set of VOCs in marine boundary layer, in particular, in situations where outflows of pollutants from the major urban centers along the coast occur, and to probe the interactions of the anthropogenic pollutants with marine atmosphere. One minute average scans were collected over a period of 24 days. Several offshore outflow episodes were identified by the increasing mixing ratios of aromatic compounds, such as benzene, toluene and C8-aromatics. Preliminary analysis suggests a relatively rapid removal of these species as a result of photochemical aging over a time scale of hours during sunrise. The observed rates of removal correspond reasonably well with those expected from OH photochemistry. Data demonstrating all of these conclusions will be shown.

Vlasenko, A. L.; Li, S.; Bon, D.; Gilman, J. B.; Kuster, W. C.; de Gouw, J. A.

2010-12-01

155

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. PMID:22666368

Firacative, Carolina; Trilles, Luciana; Meyer, Wieland

2012-01-01

156

Simple analytical strategy for MALDI-TOF-MS and nanoUPLC-MS/MS: Quantitating curcumin in food condiments and dietary supplements and screening of acrylamide-induced ROS protein indicators reduced by curcumin.  

PubMed

Curcumin is the major active ingredient of turmeric and is widely used as a preservative, flavouring and colouring agent. Curcumin is a potent substance with several functions, including antioxidant, antitumor, anti-inflammatory, antimicrobial, antiparasitic, antimutagenic, chemopreventive and chemotherapeutic activities. Matrix-assisted laser desorption/ionisation coupled with time-of-flight mass spectrometry (MALDI-TOF-MS) has been used to analyse various molecules (including natural antioxidants). This study established an expeditious method that couples MALDI-TOF-MS with a simple dilution method to quantify curcumin in food condiments and dietary supplements. The linear range of curcumin detection ranged from 1 to 100?g/mL. In further experiments, liver cells were treated with curcumin after exposure to acrylamide. Nano ultra performance liquid chromatographic system (nanoUPLC) coupled with tandem mass spectrometry (MS/MS) was used to evaluate the potential proteins and protein modifications induced by acrylamide. The results indicate that curcumin reduces the effects of reactive oxygen species induced by acrylamide. PMID:25529721

Huang, Yu-Shu; Hsieh, Tusty-Jiuan; Lu, Chi-Yu

2015-05-01

157

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

2013-11-01

158

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 Central

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

2013-01-01

159

Effect of a traditional Chinese medicine preparation Xindi soft capsule on rat model of acute blood stasis: A urinary metabonomics study based on liquid chromatography–mass spectrometry  

Microsoft Academic Search

Xindi soft capsule is a traditional Chinese medicine preparation which consists of sea buckthorn flavonoids and sea buckthorn berry oil. In this study, a urinary metabonomics method based on the ultra-performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC Q-TOF MS) was used to evaluate the efficacy and study the mechanism of traditional Chinese medicine preparation to blood

Xinjie Zhao; Yi Zhang; Xianli Meng; Peiyuan Yin; Chong Deng; Jing Chen; Zhang Wang; Guowang Xu

2008-01-01

160

Cryogen-free cryostat for large-scale arrays of superconducting tunnel junction ion detectors in time-of-flight mass spectrometry  

Microsoft Academic Search

Nb-based superconducting tunnel junction (STJ) detectors have a fast time resolution of a few 100ns and high operating temperature of 0.3K. These advantages expand their applicable fields to time-of-flight mass spectrometry (TOF-MS). In order to enlarge effective detection area, we have built arrays based on hundreds of large STJ elements. To realize the fast readout and no-cross talk, coaxial cables

A. Kushino; M. Ohkubo; Y. E. Chen; M. Ukibe; S. Kasai; K. Fujioka

2006-01-01

161

Evaluation of the Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of blood isolates of Acinetobacter species.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (Bruker Biotyper) was able to accurately identify 98.6% (142/144) of Acinetobacter baumannii isolates, 72.4% (63/87) of A. nosocomialis isolates, and 97.6% (41/42) of A. pittii isolates. All Acinetobacter junii, A. ursingii, A. johnsonii, and A. radioresistens isolates (n = 28) could also be identified correctly by Bruker Biotyper. PMID:24899038

Hsueh, Po-Ren; Kuo, Lu-Cheng; Chang, Tsung-Chain; Lee, Tai-Fen; Teng, Shih-Hua; Chuang, Yu-Chung; Teng, Lee-Jene; Sheng, Wang-Huei

2014-08-01

162

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

163

Discrimination of Escherichia coli O157, O26 and O111 from Other Serovars by MALDI-TOF MS Based on the S10-GERMS Method  

PubMed Central

Enterohemorrhagic Escherichia coli (EHEC), causes a potentially life-threatening infection in humans worldwide. Serovar O157:H7, and to a lesser extent serovars O26 and O111, are the most commonly reported EHEC serovars responsible for a large number of outbreaks. We have established a rapid discrimination method for E. coli serovars O157, O26 and O111 from other E. coli serovars, based on the pattern matching of mass spectrometry (MS) differences and the presence/absence of biomarker proteins detected in matrix-assisted laser desorption/ionization time-of-flight MS (MALDI-TOF MS). Three biomarkers, ribosomal proteins S15 and L25, and acid stress chaperone HdeB, with MS m/z peaks at 10138.6/10166.6, 10676.4/10694.4 and 9066.2, respectively, were identified as effective biomarkers for O157 discrimination. To distinguish serovars O26 and O111 from the others, DNA-binding protein H-NS, with an MS peak at m/z 15409.4/15425.4 was identified. Sequence analysis of the O157 biomarkers revealed that amino acid changes: Q80R in S15, M50I in L25 and one mutation within the start codon ATG to ATA in the encoded HdeB protein, contributed to the specific peak pattern in O157. We demonstrated semi-automated pattern matching using these biomarkers and successfully discriminated total 57 O157 strains, 20 O26 strains and 6 O111 strains with 100% reliability by conventional MALDI-TOF MS analysis, regardless of the sample conditions. Our simple strategy, based on the S10-spc-alpha operon gene-encoded ribosomal protein mass spectrum (S10-GERMS) method, therefore allows for the rapid and reliable detection of this pathogen and may prove to be an invaluable tool both clinically and in the food industry. PMID:25411793

Ojima-Kato, Teruyo; Yamamoto, Naomi; Suzuki, Mayumi; Fukunaga, Tomohiro; Tamura, Hiroto

2014-01-01

164

Proteomic analysis of Acinetobacter lwoffii K24 by 2-D gel electrophoresis and electrospray ionization quadrupole-time of flight mass spectrometry.  

PubMed

The MS/MS analysis by Electrospray ionization quadrupole-time of flight mass spectrometry (ESI-Q-TOF MS) was applied to identify proteins in proteome analysis of bacteria whose genomes are not known. The protein identification by ESI-Q-TOF MS was performed sequentially by database search and then de novo sequencing using MS/MS spectra. Soil bacteria having unanalyzed genome, Acinetobacter lwoffii K24 is an aniline degrading bacterium. In this report, we present the results of a comparison between the proteome profile of A. lwoffii K24 cultured in aniline- or succinate-containing media. Protein analysis was performed using two-dimensional gel electrophoresis (2-DE) with pH 3-10 immobilized pH gradient (IPG) strips followed by ESI-Q-TOF MS. More than 780 protein spots were detected by 2-DE from the soluble proteome. Forty-eight of these proteins were expressed exclusively in aniline cultured bacteria, and 81 proteins increased and 162 proteins decreased in aniline-cultured versus succinate cultured A. lwoffii K24. Internal amino acid sequences of 43 major protein spots were successfully determined by ESI-Q-TOF MS to try to identify the bacterial proteins responding to aniline culture condition. Since the A. lwoffii K24 genome is not yet sequenced, many proteins were found to be hypothetical. Comparative proteome analysis of the insoluble protein fractions showed that one novel protein that was strongly induced by succinate-cultured A. lwoffii K24 was repressed under aniline culture conditions. These results suggest that comprehensive analysis of bacterial proteomes by 2-DE and amino acid sequence analysis by ESI-Q-TOF MS is useful for understanding induced novel proteins of biodegrading bacteria. PMID:15134882

Kim, Eun-A; Kim, Jin Young; Kim, Soo-Jung; Park, Kyeong Ryang; Chung, Hae-Jin; Leem, Sun-Hee; Kim, Seung Il

2004-06-01

165

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for rapid identification of Brachyspira species isolated from swine, including the newly described "Brachyspira hampsonii".  

PubMed

The Brachyspira species traditionally associated with swine dysentery and other diarrheal diseases in pigs are Brachyspira hyodysenteriae, Brachyspira pilosicoli, and, to a lesser extent, Brachyspira murdochii. "Brachyspira hampsonii" is a recently proposed novel species that causes clinical disease similar to that caused by B. hyodysenteriae. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems are increasingly available in veterinary diagnostic laboratories, are less expensive, and are faster than traditional microbiological and molecular methods for identification. Thirty-three isolates associated with Brachyspira species of importance to swine were added to an existing MALDI-TOF MS database library. In total, species included in the library were: B. hyodysenteriae, "B. hampsonii" clades I and II, Brachyspira innocens, Brachyspira intermedia, B. murdochii, and B. pilosicoli. A comparison between MALDI-TOF MS and nox sequencing was completed on 176 field isolates. Of the 176 field isolates, 174 (98.9%) matched species identification by both methods. Thirty field isolates were identified by both methods as "B. hampsonii". Twenty-seven of the 30 (90%) "B. hampsonii" field isolates matched clade designation in both assays. The nox sequencing identified 26 as "B. hampsonii" clade I and 4 as clade II. Comparatively, MALDI-TOF MS identified 25 of the 30 as "B. hampsonii" clade I and 5 as clade II. The current study indicates MALDI-TOF MS is a reliable tool for the identification of swine Brachyspira species; however, final clade designation for "B. hampsonii" may still require molecular techniques. PMID:25012082

Warneke, Hallie L; Kinyon, Joann M; Bower, Leslie P; Burrough, Eric R; Frana, Timothy S

2014-09-01

166

Use of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of molds of the fusarium genus.  

PubMed

The rates of infection with Fusarium molds are increasing, and a diverse number of Fusarium spp. belonging to different species complexes can cause infection. Conventional species identification in the clinical laboratory is time-consuming and prone to errors. We therefore evaluated whether matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a useful alternative. The 289 Fusarium strains from the Belgian Coordinated Collections of Microorganisms (BCCM)/Institute of Hygiene and Epidemiology Mycology (IHEM) culture collection with validated sequence-based identities and comprising 40 species were used in this study. An identification strategy was developed, applying a standardized MALDI-TOF MS assay and an in-house reference spectrum database. In vitro antifungal testing was performed to assess important differences in susceptibility between clinically relevant species/species complexes. We observed that no incorrect species complex identifications were made by MALDI-TOF MS, and 82.8% of the identifications were correct to the species level. This success rate was increased to 91% by lowering the cutoff for identification. Although the identification of the correct species complex member was not always guaranteed, antifungal susceptibility testing showed that discriminating between Fusarium species complexes can be important for treatment but is not necessarily required between members of a species complex. With this perspective, some Fusarium species complexes with closely related members can be considered as a whole, increasing the success rate of correct identifications to 97%. The application of our user-friendly MALDI-TOF MS identification approach resulted in a dramatic improvement in both time and accuracy compared to identification with the conventional method. A proof of principle of our MALDI-TOF MS approach in the clinical setting using recently isolated Fusarium strains demonstrated its validity. PMID:25411180

Triest, David; Stubbe, Dirk; De Cremer, Koen; Piérard, Denis; Normand, Anne-Cécile; Piarroux, Renaud; Detandt, Monique; Hendrickx, Marijke

2015-02-01

167

Evaluation of the Bruker Biotyper and VITEK MS MALDI-TOF MS systems for the identification of unusual and/or difficult-to-identify microorganisms isolated from clinical specimens.  

PubMed

The purpose of this investigation was to evaluate the analytical performance characteristics of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of unusual organisms. We evaluated the accuracy of two MALDI-TOF MS systems, bioMérieux VITEK MS (database v2.0) and Bruker Biotyper (software version 3.0), for the identification of the most difficult and/or unusual microorganisms isolated from clinical specimens. Our study included 174 bacterial isolates recovered from clinical cultures at Barnes-Jewish Hospital, St. Louis, MO, from 2009 to 2013, representing 50 genera and 52 species. MS identifications were compared to the identification reported by the reference laboratory. Discrepancies were resolved using molecular methods, including 16S rRNA gene sequencing and additional molecular methods. When performed, molecular methods were considered the gold standard. Of the 168 isolates resolved to the genus level, VITEK MS identified 145 (86.3 %), and of the 114 isolates resolved to the species level, 97 (85.1 %) were correctly identified. Bruker Biotyper identified 155 (92.3 %) of 168 isolates to the genus level and 97 (85.1 %) of 114 isolates to the species level. VITEK MS and Bruker Biotyper provided no identification for 17 (10.1 %) and 12 (7.1 %) organisms, respectively, and misidentified six (3.6 %) and one (0.6 %) isolate, respectively. Six isolates (3.6 %) were not resolvable to the genus level and were excluded from data analysis due to the lack of a gold standard for comparison. There was no significant difference in the number of organisms identified to the genus level, species level, unidentified, or misidentified by the two MALDI-TOF MS systems (p = 0.11, 1.0, 0.44, and 0.12, respectively). PMID:24962194

McElvania TeKippe, E; Burnham, C-A D

2014-12-01

168

Multi-element analysis of milk by ICP-oa-TOF-MS after precipitation of calcium and proteins by oxalic and nitric acid.  

PubMed

In this work a simple technique employing oxalic and nitric acid to cow's milk samples prior to analysis by inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry (ICP-oa-TOF-MS) was introduced. After the precipitation of calcium and proteins via oxalic and nitric acid, respectively, the resulting liquid phase was aspirated with a concentric glass nebulizer for ICP-TOF-MS determination of trace elements. Precipitation of proteins is essential for better separation of solid and liquid phase of modified samples. Separation of calcium as a precipitated non-soluble oxalate enables the elimination of spectral interferences originating from different calcium containing species like (40)Ca(35)Cl(+), (40)Ca(37)Cl(+), (43)Ca(16)O(+), (40)Ca(18)O(+), (44)Ca(16)O(+), (43)Ca(16)O(1)H(+) onto the determination of As, Se, Co and Ni whose assay is more difficult when using conventional quadrupole instruments. High detection capability is further an advantage as the approach enables the analysis without dilution. The methodology may serve, in addition, for a fast and sensitive determination of some other elements. After that, direct, reliable and simultaneous determination of 16 elements (Li, Be, B, V, Cr, Mn, Ni, Co, Ga, As, Se, Mo, Sn, Sb, Cs, Tl) at trace and ultra-trace levels in milk can be performed under optimum instrumental conditions and by using Rh as an internal standard. Accuracy and precision was assessed by measuring NCS ZC73015 milk powder control standard, yielding results in agreement with certified values and RSD <10%. The accuracy was also checked by comparison of the results of the proposed method with those found by a method based on a microwave-assisted digestion of real samples. PMID:23598096

Husáková, Lenka; Urbanová, Iva; Šrámková, Jitka; Kone?ná, Michaela; Bohuslavová, Jana

2013-03-15

169

[Development of UPLC-Q-TOF-MS/MS combined with reference herb approach to rapidly screen commercial sulfur-fumigated ginseng].  

PubMed

An ultra-performance liquid chromatography-quadrupole/time of flight mass spectrometry (UPLC-Q-TOF-MS/MS) combined with reference herb method was developed to rapidly screen commercial sulfur-fumigated ginseng. Sufur-fumigated ginseng reference herb was prepared using genuine ginseng by conventional procedure. Then the reference sulfur-fumigated ginseng sample was analyzed by UPLC-Q-TOF-MS/MS to identify characteristic marker components. 25-hydroxyl-Re sulfate with higher abundance was se- lected as marker compound from 8 characteristic components identified in sulfur-fumigated ginseng reference herb. The fragmentation of 25-hydroxyl-Re sulfate was extensively investigated, fragment ion m/z 879.44 with higher intensity was chosen as the characteristic ion of sulfur-fumigated ginseng. The response of ion m/z 879. 44 was improved by optimizing the MS conditions so that this ion could be used as the characteristic marker ion for screening purpose in ion extracting screening mode. The established approach was successfully applied to inspect 21 commercial ginseng samples collected from different cities in China It was found that the chemical profiles of 9 samples were similar to that of sulfur-fumigated ginseng reference herb, and the characteristic ion m/z 879. 44 of 25-hydroxyl-Re sulfate was also detected in these samples, suggesting that there were nearly 43% ginseng samples analyzed being sulfur-fumigated. This findng agreed well with the results of sulfur dioxide residues of these 21 commercial ginseng samples determined with the method documented in Chinese Pharmacopeia Compared with the method documented in Chinese Pharmacopeia, the proposed approach is more rapid and specific for screening sulfur-fumigated ginseng. SFDA of China should strengthen the enforcement to prohibit ginseng being sulfur-fumigated, so that ginseng and it preparations could be effectively and safely benefit to the health of human beings. PMID:25423813

Zhou, Shan-Shan; Xu, Jin-Di; Shen, Hong; Liu, Huan-Huan; Li, Song-Lin

2014-08-01

170

The influence of incubation time, sample preparation and exposure to oxygen on the quality of the MALDI-TOF MS spectrum of anaerobic bacteria.  

PubMed

With matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), bacteria can be identified quickly and reliably. This accounts especially for anaerobic bacteria. Because growth rate and oxygen sensitivity differ among anaerobic bacteria, we aimed to study the influence of incubation time, exposure to oxygen and sample preparation on the quality of the spectrum using the Bruker system. Also, reproducibility and inter-examiner variability were determined. Twenty-six anaerobic species, representing 17 genera, were selected based on gram-stain characteristics, growth rate and colony morphology. Inter-examiner variation showed that experience in the preparation of the targets can be a significant variable. The influence of incubation time was determined between 24 and 96 h of incubation. Reliable species identification was obtained after 48 h of incubation for gram-negative anaerobes and after 72 h for gram-positive anaerobes. Exposure of the cultures to oxygen did not influence the results of the MALDI-TOF MS identifications of all tested gram-positive species. Fusobacterium necrophorum and Prevotella intermedia could not be identified after >24 h and 48 h of exposure to oxygen, respectively. Other tested gram-negative bacteria could be identified after 48 h of exposure to oxygen. Most of the tested species could be identified using the direct spotting method. Bifidobacterium longum and Finegoldia magna needed on-target extraction with 70% formic acid in order to obtain reliable species identification and Peptoniphilus ivorii a full extraction. Spectrum quality was influenced by the amount of bacteria spotted on the target, the homogeneity of the smear and the experience of the examiner. PMID:25039504

Veloo, A C M; Elgersma, P E; Friedrich, A W; Nagy, E; van Winkelhoff, A J

2014-12-01

171

Identification and characterization of process related impurities in chloroquine and hydroxychloroquine by LC/IT/MS, LC/TOF/MS and NMR.  

PubMed

The focus of this study is identification and characterization of major unknown impurities in chloroquine (CQ) and hydroxychloroquine (HCQ) bulk drug samples using liquid chromatography/ion trap mass spectrometry (LC/IT/MS) and liquid chromatography/time of flight mass spectrometry (LC/TOF/MS). The newly developed LC/MS method was employed for the analysis of both the drugs. The analysis revealed the presence of two impurities in each of the drugs. The impurities are designated as CQ-I, CQ-II (for chloroquine); HCQ-I and HCQ-II (for hydroxychloroquine). Three of the impurities, CQ-II, HCQ-I and HCQ-II were unknown have not been reported previously. Accurate masses of the impurities were determined by using Q-TOF mass spectrometer and fragmentation behavior was studied by an ion trap mass spectrometer. Based on the spectrometric data and synthetic specifics the structures of CQ-II, HCQ-I and HCQ-II were proposed as 1,4 pentanediamine, N(4)(7-chloro-4-quinolinyl), N(4)-chloromethyl, N(4)-ethylamine; 2-(4-(7-chloroquinolin-4-ylamino) pentylamino) ethanol and [[4-[(7-chloro-4-quinolyl) amino] N-pentyl] N-chloromethyl-N-ethylamino] ethanol respectively. The impurities were isolated by semi-preparative HPLC and structures were confirmed by NMR spectroscopy. The formation and through characterization of known CQ-I impurity is also discussed. PMID:19201565

Dongre, Vaijanath G; Ghugare, Pradeep D; Karmuse, Pravin; Singh, Dharmendra; Jadhav, Atul; Kumar, Ashok

2009-05-01

172

Analysis of new synthetic drugs by ion mobility time-of-flight mass spectrometry.  

PubMed

Characteristic ion mobility mass spectrometry data, reduced mobility, and limits of detection (signal-to-noise ratio = 3) were determined for six synthetic drugs and cocaine by ion mobility time-of-flight mass spectrometry (IM-TOF-MS) with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). The studied synthetic illicit drugs recently appeared on the recreational drug market as designer drugs and were methylone, 4-MEC (4'-methylethcathinone), 3,4-MDPV (3,4-methylenedioxypyrovalerone), JWH-210 [4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone], JWH-250 [2-(2-methoxyphenyl)-1-(1-pentyl-1H-indol-3-yl)ethanone], and JWH-203 [1-pentyl-3-(2'-chlorophenylacetyl) indole]. Absolute reduced mobilities in nitrogen were 1.35, 1.28, 1.41, 1.30, 1.18, 0.98, 1.09, and 1.07 cm2V(-1)s(-1), for methylone [M-H]+, methylone [M+H]+, 4-MEC [M-H]+, 4-MEC [M+H]+, 3,4-MDPV [M+H]+, JWH-210 [M+H]+, JWH-250 [M+H]+, and JWH-203 [M+H]+, respectively. Selected illicit drugs are easily identified by IM-TOF-MS during a 100s analysis. Relative Limits of detection ranged from 4 to 400 nM are demonstrated for these compounds. Such relative limits of detection correspond to 14 pg to 2 ng absolute limits of detection. Better detection limits are obtained in APCI mode for all the illicit drugs except cocaine. ESI mode was found to be preferable for the IM-TOF-MS detection of cocaine at trace levels. A single sample analysis is completed in an order of magnitude less time than that for conventional liquid chromatography/mass spectrometry approach. The application allows one to consider IM-TOF-MS as a good candidate for a method to determine quickly the recently surfaced designer drugs marketed on the internet as "bath salts," "spice," and "herbal blends". PMID:24895779

Sysoev, Alexey A; Poteshin, Sergey S; Chernyshev, Denis M; Karpov, Alexander V; Tuzkov, Yuriy B; Kyzmin, Vyacheslav V; Sysoev, Alexander A

2014-01-01

173

Matrix-assisted laser desorption ionisation-time of flight mass spectrometry for rapid identification of Laribacter hongkongensis.  

PubMed

Laribacter hongkongensis is a Gram-negative, facultative anaerobic, motile, S-shaped, urease-positive bacillus associated with invasive infections in liver cirrhosis patients and community-acquired gastroenteritis. Most cases of L hongkongensis infections occur in eastern countries. Information is lacking on the usefulness of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria important in eastern countries. Using the Bruker database extended with 21 L hongkongensis reference strains, all 240 L hongkongensis isolates recovered from patients, fish, frogs and water were correctly identified, with 224 (93.3%) strains having top match scores ?2.0. Notably, the strain of Chromobacterium violaceum was not reliably identified although it is included in the database. MALDI-TOF MS is useful for the accurate routine identification of L hongkongensis after adding reference L hongkongensis main spectra to the database. The number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability. PMID:23814260

Tang, Bone S F; Lau, Susanna K P; Teng, Jade L L; Chan, Tsz-Ming; Chan, Wai-Sing; Wong, Ting-Yin; Tong, Yu-Ting; Fan, Rachel Y Y; Yuen, Kwok-Yung; Woo, Patrick C Y

2013-12-01

174

Quantitative matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid resistance detection.  

PubMed

Antibiotic resistance in Gram-negative microorganisms is an increasing health care problem. The rapid detection of such resistance is crucial for starting an early specific therapy and to enable initiation of the required hygiene measures. With continued emphasis on reducing the cost of laboratory testing, only economical/low-cost approaches have a chance of being implemented. During recent years, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been developed to be a standard method in microbiology laboratories for the rapid and cost-efficient identification of microorganisms. Extending the usage of MALDI-TOF MS in the clinical microbiology laboratory to the area of resistance testing is an attractive option. Quantitative MALDI-TOF MS using an internal standard facilitates the measurement of the quantity of peptides and small proteins within a spectrum. These quantities correlate to the number of microorganisms and therefore to the growth of a microorganism. The comparison of growth in the presence or absence of an antibiotic allows for analysis of the susceptibility behavior of a strain. Here, we describe a novel method and its application in the analysis of 108 Klebsiella sp. isolates. After 1 h of incubation at a meropenem concentration of 8 ?g/ml, a sensitivity of 97.3% and a specificity of 93.5% were achieved (compared to Etest results). PMID:25232164

Lange, Christoph; Schubert, Sören; Jung, Jette; Kostrzewa, Markus; Sparbier, Katrin

2014-12-01

175

Liquid chromatography/quadrupole time-of-flight mass spectrometry for determination of saxitoxin and decarbamoylsaxitoxin in shellfish.  

PubMed

Saxitoxin (STX) and decarbamoylsaxitoxin (dcSTX) were determined by liquid chromatography with quadrupole time-of-flight mass spectrometry (Q-TOF MS). A shellfish tissue was extracted with 0.1 mol/l HCl under ultrasonication, and cleanup of extract was accomplished by solid-phase extraction with a C18 cartridge. Chromatographic separation was carried out on a C18 column (150 mm x 2.1 mm, 3.5 microm) with gradient elution of MeOH-H2O (20:80) containing 0.05% heptafluorobutyric acid and MeOH-H2O (15:85) containing 0.05% acetic acid. The protonated molecule [M + H]+ ions at m/z 257 for dcSTX and 300 for STX were selected in precursor ion scanning for Q-TOF MS in the positive electrospray ionizaion mode. Average recoveries and relative standard deviations, by analyzing samples spiked at a level of 0.1, 0.8 or 1.6 microg/g, were 84-92 and 8-14%, respectively. Identification of the presence of the toxins in shellfish tissues was based on the structural information offered by Q-TOF MS. PMID:15146927

Fang, Xiaoming; Fan, Xiang; Tang, Yifeng; Chen, Jiahua; Lu, Jingci

2004-05-21

176

A novel method to differentiate bovine and porcine gelatins in food products: nanoUPLC-ESI-Q-TOF-MS(E) based data independent acquisition technique to detect marker peptides in gelatin.  

PubMed

We presented a novel nanoUPLC-MS(E) workflow method that has potential to identify origin of gelatin in some dairy products; yoghurt, cheese and ice cream. In this study, the method was performed in two steps. In the first step, gelatin was extracted from these products before the MS-sample preparation. In the second step, tryptic gelatin peptides were separated and analyzed with ultra-performance liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry (nanoUPLC-ESI-q-TOF-MS(E)). The novelty of this setup was that it functioned in a data independent acquisition mode and that alternate low and elevated collision energy was applied to acquire precursor and product ion information. This enabled accurate mass acquisition on the peptide level to identify the gelatin peptides. The marker peptides specific for porcine and bovine could be successfully detected in the gelatin added to the dairy products analyzed, revealing that the detection of marker peptides in the digested gelatin samples using nanoUPLC-ESI-q-TOF-MS(E) could be an effective method to differentiate porcine and bovine gelatin in the dairy products. PMID:23870980

Yilmaz, Mustafa Tahsin; Kesmen, Zulal; Baykal, Betul; Sagdic, Osman; Kulen, Oktay; Kacar, Omer; Yetim, Hasan; Baykal, Ahmet Tarik

2013-12-01

177

[Identification of a new sildenafil analogue based on Q-TOF-MS].  

PubMed

The drugs such as sildenafil adulterated in herbal products and dietary supplements may endanger human health. The number of the new modified derivatives is increasing recently. Based on Q-TOF-MS, a new sildenafil analogue was found. It was isolated and purified by preparative liquid chromatography. Its structure was determined by NMR, as 1-[4-propoxy-3-(6, 7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4, 3-d] pyrimidin-5-yl)phenylsulfonyl]-4-methylpiperazine. Compared with sildenafil, the ethoxy group of the benzene ring moiety was moved to the propoxy group, which had not been reported in China. The mass spectrometric behavior pattern of the structure type was summarized, which can greatly accelerate the structural analysis of novel analogues. PMID:24974470

Sun, Jian; Yu, Hong; Hu, Qing; Feng, Rui; Zhang, Su; Ji, Shen

2014-04-01

178

Dual Polarity Accurate Mass Calibration for ESI and MALDI Mass Spectrometry Using Maltooligosaccharides  

PubMed Central

In view of the fact that memory effects associated with instrument calibration hinder the use of many m/z and tuning standards, identification of robust, comprehensive, inexpensive, and memory-free calibration standards are of particular interest to the mass spectrometry community. Glucose and its isomers are known to have a residue mass of 162.05282 Da; therefore, both linear and branched forms of poly-hexose oligosaccharides possess well defined masses making them ideal candidates for mass calibration. Using a wide range of maltooligosaccharides (MOS) derived from commercially available beers, ions with m/z ratios from ~500 Da to 2500 Da or more have been observed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and time of flight mass spectrometry (TOF-MS). The mixtures of MOS were further characterized using infrared multiphoton dissociation (IRMPD) and nano-liquid chromatography/mass spectrometry (nano-LC/MS). In addition to providing well defined series of positive and negative calibrant ions using either ESI or MALDI, the MOS are not encumbered by memory effects and are thus well suited mass calibration and instrument tuning standards for carbohydrate analysis. PMID:18655765

Clowers, Brian H.; Dodds, Eric D.; Seipert, Richard R.; Lebrilla, Carlito B.

2009-01-01

179

MALDI-TOF mass spectrometry for rapid identification of clinical fungal isolates based on ribosomal protein biomarkers.  

PubMed

This study aimed to evaluate the identification of clinical fungal isolates (yeast and molds) by protein profiling using Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS). A total of 125 clinical fungal culture isolates (yeast and filamentous fungi) were collected. The test set included 88 yeast isolates (Candida albicans, Candida glabrata, Candida guilliermondii, Candida kefyr, Candida krusei, Candida parapsilosis, Candida rugosa, Candida tropicalis and Cryptococcus neoformans) and 37 isolates of molds (Alternaria spp., Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Cunninghamella spp., Histoplasma capsulatum, Microsporum gypseum, Microsporum nanum, Rhizomucor spp. and Trichophyton spp.). The correlation between MALDI TOF MS and conventional identification for all these 125 fungal isolates included in the study was 87.2% at the species level and 90.4% at the genus level. MALDI TOF MS results revealed that the correlation in yeast (n=88) identification was 100% both at the genus and species levels whereas, the correlation in mold (n=37) identification was more heterogeneous i.e. 10.81% isolates had correct identification up to the genus level, 56.7% isolates had correct identification both at the genus and species levels, whereas 32.42% isolates were deemed Not Reliable Identification (NRI). But, with the modification in sample preparation protocol for molds, there was a significant improvement in identification. 86.4% isolates had correct identification till the genus and species levels whereas, only 2.7% isolates had Not Reliable Identification. In conclusion, this study demonstrates that MALDI-TOF MS could be a possible alternative to conventional techniques both for the identification and differentiation of clinical fungal isolates. However, the main limitation of this technique is that MS identification could be more precise only if the reference spectrum of the fungal species is available in the database. PMID:25541362

Panda, Ashutosh; Ghosh, Anup K; Mirdha, Bijay R; Xess, Immaculata; Paul, Saikat; Samantaray, Jyotish C; Srinivasan, Alagiri; Khalil, Shehla; Rastogi, Neha; Dabas, Yubhisha

2015-02-01

180

Identification and differentiation of food-related bacteria: A comparison of FTIR spectroscopy and MALDI-TOF mass spectrometry.  

PubMed

The food industry requires easy, accurate, and cost-effective techniques for microbial identification to ensure safe products and identify microbial contaminations. In this work, FTIR spectroscopy and MALDI-TOF mass spectrometry were assessed for their suitability and applicability for routine microbial diagnostics of food-related microorganisms by analyzing their robustness according to changes in incubation time and medium, identification accuracy and their ability to differentiate isolates down to the strain level. Changes in the protocol lead to a significantly impaired performance of FTIR spectroscopy, whereas they had only little effects on MALDI-TOF MS. Identification accuracy was tested using 174 food-related bacteria (93 species) from an in-house strain collection and 40 fresh isolates from routine food analyses. For MALDI-TOF MS, weaknesses in the identification of bacilli and pseudomonads were observed; FTIR spectroscopy had most difficulties in identifying pseudomonads and enterobacteria. In general, MALDI-TOF MS obtained better results (52-85% correct at species level), since the analysis of mainly ribosomal proteins is more robust and seems to be more reliable. FTIR spectroscopy suffers from the fact that it generates a whole-cell fingerprint and intraspecies diversity may lead to overlapping species borders which complicates identification. In the present study values between 56% and 67% correct species identification were obtained. On the opposite, this high sensitivity offers the opportunity of typing below the species level which was not possible using MALDI-TOF MS. Using fresh isolates from routine diagnostics, both techniques performed well with 88% (MALDI-TOF) and 75% (FTIR) correct identifications at species level, respectively. PMID:24878140

Wenning, Mareike; Breitenwieser, Franziska; Konrad, Regina; Huber, Ingrid; Busch, Ulrich; Scherer, Siegfried

2014-08-01

181

Initializing a digital chromatography data archive for tropospheric air samples on Taunus Observatory Frankfurt by GC-TOF-MS  

NASA Astrophysics Data System (ADS)

The inception of a digital air archive for halogenated hydrocarbons will be presented. This archive is based on weekly samples taken at the Taunus Observatory on "Kleiner Feldberg" near Frankfurt/ Main, i.e. a very central position in Germany. The station is characterized by a mixture of clean air, moderately polluted air and occasional influence from the nearby city of Frankfurt. Regular meteorological and air quality data are available from the German Weather service (DWD) and the regional air quality monitoring (Hessiche Landesanstalt für Umwelt und Geologie, HLUG). Two air samples are collected in parallel in 2 l stainless steel flasks using a metal bellows pump. The air samples are analysed in the laboratory by gas chromatography coupled with Time of Flight Mass Spectrometry (GC TOF MS) and Quadrupole Mass Spectrometry (GC QUAD MS) for halogenated trace gases. Analysis is carried out no later than a month after sampling. Our current target species which will be measured by both mass spectrometers contain a wide range of halogenated trace gases, with calibration scales linked to both global monitoring networks, i.e. NOAA and AGAGE. A Time of Flight Mass Spectrometer has the advantage to measure a full mass range with a high sensitivity. Other measuring networks use Quadrupole mass spectrometers which need to be tuned to selected masses in order to achieve sufficient sensitivity. The full mass scan information available in the TOF data in combination with the high sensitivity of the instrument opens the possibility for retrospective analysis of the data in the future, as information on all substances which can be trapped and desorbed using our sampling technique are recorded, even though they may not be retrieved at the time of measurements. This will open the opportunity to have a look on historical developments even of yet undiscovered halogenated trace gases or those, which have not been subject to one's research focus until a certain time point but have become interesting later. The full resolution mass spectrometric data will be stored together with all meteorological and other information necessary for later reprocessing. This will constitute a digital air archive, which can also be made available to other research groups for reanalysis.

Hoker, Jesica; Obersteiner, Florian; Bönisch, Harald; Engel, Andreas

2014-05-01

182

Two-step Laser Time-of-Flight Mass Spectrometry to Elucidate Organic Diversity in Planetary Surface Materials.  

NASA Technical Reports Server (NTRS)

Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) holds promise to be a low-mass, compact in situ analytical capability for future landed missions to planetary surfaces. The ability to analyze a solid sample for both mineralogical and preserved organic content with laser ionization could be compelling as part of a scientific mission pay-load that must be prepared for unanticipated discoveries. Targeted missions for this instrument capability include Mars, Europa, Enceladus, and small icy bodies, such as asteroids and comets.

Getty, Stephanie A.; Brinckerhoff, William B.; Cornish, Timothy; Li, Xiang; Floyd, Melissa; Arevalo, Ricardo Jr.; Cook, Jamie Elsila; Callahan, Michael P.

2013-01-01

183

What is Mass Spectrometry?  

NSDL National Science Digital Library

This site from the American Society for Mass Spectrometry includes information about what mass spectometry is and how it is used. It has many useful figures and references to other materials. The material answers questions such as "What is mass spectrometry and what can it do for you?"

Chiu, Chia M.

184

Guanidination of Tryptic Peptides without Desalting for MALDI-TOF MS Analysis  

PubMed Central

Derivatizations that enhance mass spectral quality often require desalting which presents as a bottleneck in MALDI-TOF MS-proteomics. Guanidination, which converts lysine to homoarginine, an arginine analog, can increase detection of those peptides 5 – 15-fold. Our aim was to improve guanidination by using a novel reagent, O-methylisourea-freebase. In a simple reaction, interfering salts were removed prior to guanidination. Freebase preparation took about 30 min and could be applied to samples all at once as opposed to desalting samples one-by-one for 5 min each. For freebase guanidinated BSA tryptic peptides, more than 6-times the peptides were observed relative to tryptic peptides or those guanidinated with the conventional reagent, O-methylisourea hemisulfate. Peptide signals increased more than 10-fold relative to those from guanidination with the conventional reagent and were equivalent to those from conventional guanidination with desalting. In addition, freebase guanidination allowed for a lower limit of detection when combined with another derivatization, N-terminal sulfonation, as evidenced by MS/MS fragmentation analysis of in-gel digests of cytochrome c. Freebase guanidination of rat lung proteins after 2-D gel electrophoresis allowed for identification of all tested protein spots regardless of protein characteristics (MW or pI) or abundance. Co-derivatization with N-terminal sulfonation confirmed the identity of low abundance proteins in 2-D gel spots that contained more than one protein. The freebase guanidination reagent is simple to prepare and to implement. Desalting is not needed prior to MALDI-TOF MS. Freebase guanidination effectively increases the dynamic range of detection of lysine-containing peptides while decreasing the work needed for sample preparation. PMID:23964694

Baker, Margaret R.; Li, Qing X.

2013-01-01

185

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

2013-03-01

186

Identification of Anaerobic Bacteria by Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry with On-Plate Formic Acid Preparation  

PubMed Central

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.

2013-01-01

187

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

188

New palytoxin-like molecules in Mediterranean Ostreopsis cf. ovata (dinoflagellates) and in Palythoa tuberculosa detected by liquid chromatography-electrospray ionization time-of-flight mass spectrometry.  

PubMed

A rapid, high resolution liquid chromatography coupled with ElectroSpray Ionization Time-Of-Flight Mass Spectrometry (ESI/TOF/MS) method was developed for the determination of the toxin pattern in cultured cells of Ostreopsis cf. ovata from the Mediterranean Sea. The samples were separated on a Phenomenex Luna 3? HILIC 200A (150 × 2.00 mm) and analyzed by LC/TOF/MS with electrospray ionization (ESI) interface in positive ion mode. The method developed here provides the capability for a fully automated analysis, which requires relatively easy sample preparation and gives clean and simple chromatograms. The method was successfully applied to the determination of ovatoxin-a, mascarenotoxin-a and four new palytoxins in O. cf. ovata. Another new palytoxin was detected in the standard material from Palythoa tuberculosa provided by Wako Chemicals. PMID:20797402

Rossi, Rachele; Castellano, Vincenzo; Scalco, Eleonora; Serpe, Luigi; Zingone, Adriana; Soprano, Vittorio

2010-12-01

189

The Use of MALDI-TOF Mass Spectrometry, Ribotyping and Phenotypic Tests to Identify Lactic Acid Bacteria from Fermented Cereal Foods in Abidjan (Côte d’Ivoire)  

PubMed Central

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) protein analysis, automated ribotyping, and phenotypic tests (e.g., cell morphology, gas production from glucose, growth and acid production on homofermemtative-heterofermentative differential (HHD) agar medium, sugar fermentation patterns) were used to identify 23 lactic acid bacteria (LAB) isolated from fermented cereal foods available in Abidjan, Côte d’Ivoire. Pediococcus acidilactici (56.5%), Lactobacillus fermentum (30.4%), L. salivarius (4.3%), P. pentosaceus (4.3%) and L. plantarum subsp. plantarum (4.3%) were the species and subspecies identified. Protein based identification was confirmed by automated ribotyping for selected isolates and was similar to that provided by the phenotypic characterization. MALDI-TOF MS protein analysis provided a high level of discrimination among the isolates and could be used for the rapid screening of LAB starter cultures. PMID:25279017

Soro-Yao, Amenan A; Schumann, Peter; Thonart, Philippe; Djè, Koffi M; Pukall, Rüdiger

2014-01-01

190

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

191

Comprehensive quantitative analysis of Shuang-Huang-Lian oral liquid using UHPLC-Q-TOF-MS and HPLC-ELSD.  

PubMed

Shuang-Huang-Lian oral liquid (SHL) is a well-known Chinese patent drug containing three herbal medicines: Radix Scutellariae, Flos Lonicerae Japonicae and Fructus Forsythiae. It is usually used to treat acute upper respiratory tract infection caused by virus or bacteria. Although the licensing of botanical drug Veregen approved by FDA has indicated the importance of quantitative analysis in quality control of herbal medicines, quantitative evaluation of a Chinese patent drug like SHL remains a challenge due to the complex chemical profile. In this study, 15 small molecular components of SHL (four flavonoids, six quinic acid derivatives, three saponins and two phenylethanoid glycosides) were simultaneously determined using ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). The contents of the three major saccharides, namely fructose, glucose and sucrose were quantified using high performance liquid chromatography-evaporative light scattering detector on an amino column (HPLC-ELSD). The macromolecules were quantified by precipitating in 80% ethanol, drying the precipitate, and then weighing. The established methods were validated in terms of linearity, sensitivity, precision, accuracy and stability and then successfully applied to analyze 12 batches of commercial products of SHL produced by four different manufacturers. The results indicated that 57.52-78.11% (w/w) of SHL could be quantitatively determined (non-saccharide small molecules: 1.77-3.75%, monosaccharides: 0.93-20.93%, macromolecules: 2.63-5.76% and sucrose: 49.20-65.94%). This study may provide a useful way to comprehensively evaluate the quality of SHL. PMID:25222137

Zhang, Tian-Bo; Yue, Rui-Qi; Xu, Jun; Ho, Hing-Man; Ma, Dik-Lung; Leung, Chung-Hang; Chau, Siu-Leung; Zhao, Zhong-Zhen; Chen, Hu-Biao; Han, Quan-Bin

2015-01-01

192

Comparison and optimization of two MALDI-TOF MS platforms for the identification of medically relevant yeast species.  

PubMed

The rapid identification of yeast is essential for the optimization of antifungal therapy. The objective of our study was to evaluate two matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) platforms, the bioMérieux VITEK MS (IVD Knowledgebase v.2.0) and Bruker Biotyper (software version 3.1), for the rapid identification of medically relevant yeast. One hundred and seventeen isolates, representing six genera and 18 species, were analyzed using multiple direct smear methods to optimize identification. Sequence analysis was the gold standard for comparison. Isolates were analyzed with VITEK MS using the direct smear method +/- a 25 % formic acid on-plate extraction. For Biotyper, isolates were analyzed using direct smear without formic acid, and with 25 % and 100 % formic acid on-plate extractions. When all methods were included, VITEK MS correctly identified 113 (96.6 %) isolates after 24 h with one misidentification, and Biotyper correctly identified 77 (65.8 %) isolates using a threshold of ?2.0 with no misidentifications. Using a revised threshold of ?1.7, Biotyper correctly identified 103 (88.0 %) isolates, with 3 (2.6 %) misidentifications. For both platforms, the number of identifications was significantly increased using a formic acid overlay (VITEK MS, p?

Pence, M A; McElvania TeKippe, E; Wallace, M A; Burnham, C-A D

2014-10-01

193

Gas Chromatography -Mass Spectrometry  

E-print Network

GCMS - 1 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS OF ETHANOL AND BENZENE IN GASOLINE Last updated: June 17, 2014 #12;GCMS - 2 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS). The goal of this experiment is to separate the components in a sample of gasoline using Gas Chromatography

Nizkorodov, Sergey

194

Rapid analysis of multiple pesticide residues in fruit-based baby food using programmed temperature vaporiser injection–low-pressure gas chromatography–high-resolution time-of-flight mass spectrometry  

Microsoft Academic Search

A rapid method using programmed temperature vaporiser injection–low-pressure gas chromatography–high-resolution time-of-flight mass spectrometry (PTV–LP-GC–HR-TOF-MS) for the analysis of multiple pesticide residues in fruit-based baby food was developed. The fast and inexpensive buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method and “conventional” approach that employs ethyl acetate extraction followed by gel permeation chromatography (GPC) cleanup were employed for

Tomas Cajka; Jana Hajslova; Ondrej Lacina; Katerina Mastovska; Steven J. Lehotay

2008-01-01

195

Misidentification of Saprochaete clavata as Magnusiomyces capitatus in Clinical Isolates: Utility of Internal Transcribed Spacer Sequencing and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Importance of Reliable Databases  

PubMed Central

Saprochaete clavata and Magnusiomyces capitatus are human pathogens that are frequently mistaken for each other due to their similar phenotypes and erroneous or limited databases. Based on internal transcribed spacer (ITS) sequences, we propose species-specific carbon assimilation patterns and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) fingerprints that enable the identification of S. clavata, M. capitatus, and Galactomyces candidus to the species level. PMID:24696028

Desnos-Ollivier, Marie; Blanc, Catherine; Garcia-Hermoso, Dea; Hoinard, Damien; Alanio, Alexandre

2014-01-01

196

Misidentification of Saprochaete clavata as Magnusiomyces capitatus in clinical isolates: utility of internal transcribed spacer sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry and importance of reliable databases.  

PubMed

Saprochaete clavata and Magnusiomyces capitatus are human pathogens that are frequently mistaken for each other due to their similar phenotypes and erroneous or limited databases. Based on internal transcribed spacer (ITS) sequences, we propose species-specific carbon assimilation patterns and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) fingerprints that enable the identification of S. clavata, M. capitatus, and Galactomyces candidus to the species level. PMID:24696028

Desnos-Ollivier, Marie; Blanc, Catherine; Garcia-Hermoso, Dea; Hoinard, Damien; Alanio, Alexandre; Dromer, Françoise

2014-06-01

197

MALDI-TOF MS analysis of ribosomal proteins coded in S10 and spc operons rapidly classified the Sphingomonadaceae as alkylphenol polyethoxylate-degrading bacteria from the environment.  

PubMed

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) using ribosomal subunit proteins coded in the S10-spc-alpha operon as biomarkers was applied for the classification of the Sphingomonadaceae from the environment. To construct a ribosomal protein database, S10-spc-alpha operon of type strains of the Sphingomonadaceae and their related alkylphenol polyethoxylate (APEO(n) )-degrading bacteria were sequenced using specific primers designed based on nucleotide sequences of genome-sequenced strains. The observed MALDI mass spectra of intact cells were compared with the theoretical mass of the constructed ribosomal protein database. The nine selected biomarkers coded in the S10-spc-alpha operon, L18, L22, L24, L29, L30, S08, S14, S17, and S19, could successfully distinguish the Sphingopyxis terrae NBRC 15098(T) and APEO(n) -degrading bacteria strain BSN20, despite only one base difference in the 16S rRNA gene sequence. This method, named the S10-GERMS (S10-spc-alpha operon gene-encoded ribosomal protein mass spectrum) method, is a significantly useful tool for bacterial discrimination of the Sphingomonadaceae at the strain level and can detect and monitor the main APEO(n) -degrading bacteria in the environment. PMID:22324315

Hotta, Yudai; Sato, Hiroaki; Hosoda, Akifumi; Tamura, Hiroto

2012-05-01

198

MALDI-TOF mass spectrometry as a tool for the discrimination of high-risk Escherichia coli clones from phylogenetic groups B2 (ST131) and D (ST69, ST405, ST393).  

PubMed

Reliable, quick and low-cost methods are needed for the early detection of multidrug-resistant and highly virulent high-risk B2 and D Escherichia coli clones or clonal complexes (HiRCC). Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) seems to have a good discriminatory potential at different subspecies levels, but it was never evaluated for the discrimination of E. coli clones. We assessed the potential of MALDI-TOF MS coupled to multivariate data analysis to discriminate representative E. coli B2 and D HiRCC. Seventy-three E. coli isolates from B2 (including ST131 and B2 non-ST131 clones) and D (ST69, ST393, ST405) with variable pulsed-field gel electrophoresis (PFGE) patterns, origins and dates (1980-2010) were tested. MS spectra were acquired from independent extracts obtained from different plate cultures in two different Microflex LT MALDI-TOF devices (Bruker) after a standard extraction procedure. MALDI-TOF MS fingerprinting analysis revealed a good discriminatory ability between the four HiRCC analysed (ST131, ST69, ST405, ST393) and between B2 ST131 and other B2 non-ST131 isolates. Clusters defined by MALDI-TOF MS were consistent with the clonal complexes assigned by multilocus sequence typing (MLST), although differences were detected regarding the composition of clusters obtained by the comparison of PFGE profiles. We demonstrate, for the first time, that characteristic mass fingerprints of different E. coli HiRCC are sufficiently discriminatory and robust to enable their differentiation by MALDI-TOF MS, which might represent a promising tool for the optimisation of infection control, individual patient management and large-scale epidemiological studies of public health relevance. The good correlation between phenotypic and genotypic features further corroborates phylogenetic relationships delineated by MLST. PMID:24599708

Novais, Â; Sousa, C; de Dios Caballero, J; Fernandez-Olmos, A; Lopes, J; Ramos, H; Coque, T M; Cantón, R; Peixe, L

2014-08-01

199

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

200

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

2012-10-01

201

Chemical analysis of pharmaceuticals and explosives in fingermarks using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.  

PubMed

Chemical analysis of latent fingermarks, "touch chemistry," has the potential of providing intelligence or forensically relevant information. Matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF MS) was used as an analytical platform for obtaining mass spectra and chemical images of target drugs and explosives in fingermark residues following conventional fingerprint development methods and MALDI matrix processing. There were two main purposes of this research: (1) develop effective laboratory methods for detecting drugs and explosives in fingermark residues and (2) determine the feasibility of detecting drugs and explosives after casual contact with pills, powders, and residues. Further, synthetic latent print reference pads were evaluated as mimics of natural fingermark residue to determine if the pads could be used for method development and quality control. The results suggest that artificial amino acid and sebaceous oil residue pads are not suitable to adequately simulate natural fingermark chemistry for MALDI/TOF MS analysis. However, the pads were useful for designing experiments and setting instrumental parameters. Based on the natural fingermark residue experiments, handling whole or broken pills did not transfer sufficient quantities of drugs to allow for definitive detection. Transferring drugs or explosives in the form of powders and residues was successful for preparing analytes for detection after contact with fingers and deposition of fingermark residue. One downfall to handling powders was that the analyte particles were easily spread beyond the original fingermark during development. Analyte particles were confined in the original fingermark when using transfer residues. The MALDI/TOF MS was able to detect procaine, pseudoephedrine, TNT, and RDX from contact residue under laboratory conditions with the integration of conventional fingerprint development methods and MALDI matrix. MALDI/TOF MS is a nondestructive technique which provides chemical information in both the mass spectra and chemical images. PMID:24447453

Kaplan-Sandquist, Kimberly; LeBeau, Marc A; Miller, Mark L

2014-02-01

202

Preserving the chromatographic integrity of high-speed supercritical fluid chromatography separations using time-of-flight mass spectrometry.  

PubMed

The advantage of high-speed time-of-flight-mass spectrometry (TOF-MS) detection for ultrafast qualitative supercritical fluid chromatography/mass spectrometry (SFC/MS) applications allows the superior resolving power of SFC to be exploited in high-throughput analysis. A chromatographic comparison of quadrupole MS and TOF-MS shows high-speed TOF total ion current data point sampling to be more indicative of fast SFC separations and corresponding short (1-2 s) baseline peak widths. Results shown for analysis of a six-compound mixture with two peaks eluting at 0.86 and 0.89 min exhibit >50% resolution by high-speed TOF data sampling, whereas the same peaks appear to coelute using quadrupole MS data sampling. Additionally, a marked improvement in the peak baseline widths is afforded by fast TOF data acquisition of 0.1 s/spectrum, resulting in a reduction in the baseline width, 1.6 s, of sulfanilamide in a four-compound mixture that is more than 2-fold greater than that achieved at the slower data acquisition of 0.5 s/spectrum. The resulting increase in resolution and improved peak shapes allow automatic integration routines to perform more effectively. For most classes of compounds amenable to high performance liquid chromatography, including druglike species, steroids, and polymers, the union of SFC with TOF-MS provides the maximum density of chemical information per unit time available with any high-speed chromatographic/mass spectrometric method. PMID:12857113

Bolaños, Ben J; Ventura, Manuel C; Greig, Michael J

2003-01-01

203

OmpU as a biomarker for rapid discrimination between toxigenic and epidemic Vibrio cholerae O1/O139 and non-epidemic Vibrio cholerae in a modified MALDI-TOF MS assay  

PubMed Central

Background Cholera is an acute diarrheal disease caused by Vibrio cholerae. Outbreaks are caused by a genetically homogenous group of strains from serogroup O1 or O139 that are able to produce the cholera toxin. Rapid detection and identification of these epidemic strains is essential for an effective response to cholera outbreaks. Results The use of ferulic acid as a matrix in a new MALDI-TOF MS assay increased the measurable mass range of existing MALDI-TOF MS protocols for bacterial identification. The assay enabled rapid discrimination between epidemic V. cholerae O1/O139 strains and other less pathogenic V. cholerae strains. OmpU, an outer membrane protein whose amino acid sequence is highly conserved among epidemic strains of V. cholerae, appeared as a discriminatory marker in the novel MALDI-TOF MS assay. Conclusions The extended mass range of MALDI-TOF MS measurements obtained by using ferulic acid improved the screening for biomarkers in complex protein mixtures. Differences in the mass of abundant homologous proteins due to variation in amino acid sequences can rapidly be examined in multiple samples. Here, a rapid MALDI-TOF MS assay was developed that could discriminate between epidemic O1/O139 strains and other less pathogenic V. cholerae strains based on differences in mass of the OmpU protein. It appeared that the amino acid sequence of OmpU from epidemic V. cholerae O1/O139 strains is unique and highly conserved. PMID:24943244

2014-01-01

204

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. PMID:21742802

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

2011-01-01

205

Recognition of Clostridium difficile PCR-ribotypes 001, 027 and 126/078 using an extended MALDI-TOF MS system.  

PubMed

During the last decade, Clostridium difficile infection (CDI) increased markedly inside as well as outside of hospitals. In association with the occurrence of new hypervirulent C. difficile strains, CDI became more important. Until now typing of C. difficile strains has been enabled by PCR-ribotyping. However, this method is restricted to specialized laboratories combined with high maintenance cost. Therefore, we tested MALDI-TOF mass spectrometry for typing of C. difficile to provide a fast method for surveillance of CDI. Using a standard set of 25 different C. difficile PCR ribotypes a database was made by different mass spectra recorded in the SARAMIS software (AnagnosTec, Zossen, Germany). The database was validated with 355 C. difficile strains belonging to 29 different PCR ribotypes collected prospectively from all submitted feces samples in 2009. The most frequent PCR ribotypes were type 001 (70%), 027 (4.8%) and 078/126 (4.7%). All three types were recognized by MALDI-TOF MS. We conclude that an extended MALDI-TOF system was capable to recognize specific markers for ribotypes 001, 027 and 078/126 allowing an effective identification of these strains. PMID:21503840

Reil, M; Erhard, M; Kuijper, E J; Kist, M; Zaiss, H; Witte, W; Gruber, H; Borgmann, S

2011-11-01

206

Rapid identification of Mycoplasma pulmonis isolated from laboratory mice and rats using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

Mycoplasma species identification is based on biochemical, immunological, and molecular methods that require several days for accurate identification. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a novel method for identification of bacteria and has recently been introduced into the clinical microbiology laboratory as a rapid and accurate technique. This method allows a characteristic mass spectral fingerprint to be obtained from whole inactivated mycoplasmal cells. In this study, we evaluated the performance of the MALDI-TOF MS for the identification of Mycoplasma by comparison with standard sequence analysis of 16S rRNA. We developed the first database of MALDI-TOF MS profiles of Mycoplasma species, containing Mycoplasma pulmonis, M. arthritidis, and M. neurolyticum, which are the most common pathogens in mice and/or rats, and species-specific spectra were recorded. Using the database, 6 clinical isolates were identified. Six tracheal swabs from 4 mice and 2 rats were cultured on PPLO agar for 4 to 7 days, and the colonies were directly applied to analyze the protein profiles. Five strains were identified as M. pulmonis, and 1 strain from a mouse was identified as M. neurolyticum (spectral scores were >2.00); the results were consistent with the results of the 16S rRNA gene sequence analysis (homologies>97.0%). These data indicate that MALDI-TOF MS can be used as a clearly rapid, accurate, and cost-effective method for the identification of M. pulmonis isolates, and this system may represent a serious alternative for clinical laboratories to identify Mycoplasma species. PMID:22498928

Goto, Kazuo; Yamamoto, Mikachi; Asahara, Miwa; Tamura, Takashi; Matsumura, Mitsuru; Hayashimoto, Nobuhito; Makimura, Koichi

2012-08-01

207

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

208

Sequence analysis of styrenic copolymers by tandem mass spectrometry.  

PubMed

Styrene and smaller molar amounts of either m-dimethylsilylstyrene (m-DMSS) or p-dimethylsilylstyrene (p-DMSS) were copolymerized under living anionic polymerization conditions, and the compositions, architectures, and sequences of the resulting copolymers were characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem mass spectrometry (MS(2)). MS analysis revealed that linear copolymer chains containing phenyl-Si(CH3)2H pendants were the major product for both DMSS comonomers. In addition, two-armed architectures with phenyl-Si(CH3)2-benzyl branches were detected as minor products. The comonomer sequence in the linear chains was established by MS(2) experiments on lithiated oligomers, based on the DMSS content of fragments generated by backbone C-C bond scissions and with the help of reference MS(2) spectra obtained from a polystyrene homopolymer and polystyrene end-capped with a p-DMSS block. The MS(2) data provided conclusive evidence that copolymerization of styrene/DMSS mixtures leads to chains with a rather random distribution of the silylated comonomer when m-DMSS is used, but to chains with tapered block structures, with the silylated units near the initiator, when p-DMSS is used. Hence, MS(2) fragmentation patterns permit not only differentiation of the sequences generated in the synthesis, but also the determination of specific comonomer locations along the polymer chain. PMID:25181590

Yol, Aleer M; Janoski, Jonathan; Quirk, Roderic P; Wesdemiotis, Chrys

2014-10-01

209

Analysis of RNA cleavage by MALDI-TOF mass spectrometry.  

PubMed

A method of analysis is presented that utilizes matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to monitor the kinetics and products of RNA cleavage, by use of a program designed to mass-match observed MS peaks with predicted RNA cleavage products. The method is illustrated through application to the study of targeted oxidation of RNA stem loops from HIV-1 Rev Response Element mRNA (RRE RNA) and ribosomal 16S A-site RNA (16S RNA) by metallonucleases. Following incubation of each RNA with catalysts and/or redox co-reactants, reaction mixtures were desalted, and MALDI-TOF MS was used to monitor both time-resolved formation of cleavage products and disappearance of full-length RNA. For each RNA, a unique list was generated that contained the predicted masses of both the full-length, and all of the possible RNA cleavage fragments that resulted from the combination of all possible cleavage sites and each of the six expected overhangs formed at nascent termini adjacent to the cleavage sites. The overhangs corresponded to 2',3'-cyclic phosphate, 3'-phosphate, 3'-phosphoglycolate, 5'- hydroxyl and 5'- phosphate, which corresponded to differing oxidative, hydrolytic, and/or 2'-OH-mediated-endonucleolytic modes of scission. Each mass spectrum was compared with a corresponding list of predicted masses, and peaks were rapidly assigned by use of a Perl script, with a mass-matching tolerance of 200 ppm. Both time-dependent cleavage mediated by metallonucleases and MALDI-TOF-induced fragmentation were observed, and these were distinguished by time-dependent experiments. The resulting data allowed a semi-quantitative assessment of the rate of formation of each overhang at each nucleotide position. Limitations included artifactual skewing of quantification by mass bias, a limited mass range for quantification, and a lack of detection of secondary cleavage products. Nevertheless, the method presented herein provides a rapid, accurate, highly-detailed and semi-quantitative analysis of RNA cleavage that should be widely applicable. PMID:22941655

Joyner, Jeff C; Keuper, Kevin D; Cowan, J A

2013-01-01

210

Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry To Resolve Complex Clinical Cases of Patients with Recurrent Bacteremias  

PubMed Central

Matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method of identifying microorganisms. Throughout Europe, it is already in routine use but has not yet been widely implemented in the United States, pending FDA approval. Here, we describe two medically complex patients at a large tertiary-care academic medical center with recurring bacteremias caused by distinct but related species. Bacterial identifications were initially obtained using the Vitek-2 system with the GPI card for Enterococcus and the API system for staphylococci. Initial results misled clinicians as to the source and proper management of these patients. Retrospective investigation with MALDI-TOF MS clarified the diagnosis by identifying a single microorganism as the pathogen in each case. To our knowledge, this is one of the first reports in the United States demonstrating the use of MALDI-TOF MS to facilitate the clinical diagnosis in patients with recurrent bacteremias of unclear source. PMID:23536408

Nori, Priya; Ostrowsky, Belinda; Dorokhova, Olena; Gialanella, Philip; Moy, Morgan; Muggia, Victoria; Grossberg, Robert; Kornblum, John; Lin, Ying

2013-01-01

211

Comparison of the Bruker MALDI-TOF Mass Spectrometry System and Conventional Phenotypic Methods for Identification of Gram-Positive Rods  

PubMed Central

In recent years, MALDI-TOF Mass Spectrometry (MS) method has emerged as a promising and a reliable tool for bacteria identification. In this study we compared Bruker MALDI-TOF MS and conventional phenotypic methods to identify a collection of 333 Gram-positive clinical isolates comprising 22 genera and 60 species. 16S rRNA sequencing was the reference molecular technique, and rpoB gene sequecing was used as a secondary gene target when 16Sr RNA did not allow species identification of Corynebacterium spp. We also investigate if score cut-offs values of ?1,5 and ?1,7 were accurate for genus and species-level identification using the Bruker system. Identification at species level was obtained for 92,49% of Gram-positive rods by MALDI-TOF MS compared to 85,89% by phenotypic method. Our data validates the score ?1,5 for genus level and ?1,7 for species-level identification in a large and diverse collection of Gram-positive rods. The present study has proved the accuracy of MALDI-TOF MS as an identification method in Gram-positive rods compared to currently used methods in routine laboratories. PMID:25184254

Barberis, Claudia; Almuzara, Marisa; Join-Lambert, Olivier; Ramírez, María Soledad; Famiglietti, Angela; Vay, Carlos

2014-01-01

212

Direct Analysis in Real Time Mass Spectrometry (DART-MS) Analysis of Skin Metabolome Changes in the Ultraviolet B-Induced Mice  

PubMed Central

Ultraviolet (UV) radiation is a major environmental factor that leads to acute and chronic reactions in the human skin. UV exposure induces wrinkle formation, DNA damage, and generation of reactive oxygen species (ROS). Most mechanistic studies of skin physiology and pharmacology related with UV-irradiated skin have focused on proteins and their related gene expression or single- targeted small molecules. The present study identified and analyzed the alteration of skin metabolites following UVB irradiation and topical retinyl palmitate (RP, 5%) treatment in hairless mice using direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) with multivariate analysis. Under the negative ion mode, the DART ion source successfully ionized various fatty acids including palmitoleic and linolenic acid. From DART-TOF-MS fingerprints measured in positive mode, the prominent dehydrated ion peak (m/z: 369, M+H-H2O) of cholesterol was characterized in all three groups. In positive mode, the discrimination among three groups was much clearer than that in negative mode by using multivariate analysis of orthogonal partial-least squares-discriminant analysis (OPLS-DA). DART-TOF-MS can ionize various small organic molecules in living tissues and is an efficient alternative analytical tool for acquiring full chemical fingerprints from living tissues without requiring sample preparation. DART-MS measurement of skin tissue with multivariate analysis proved to be a powerful method to discriminate between experimental groups and to find biomarkers for various experiment models in skin dermatological research. PMID:24404338

Park, Hye Min; Kim, Hye Jin; Jang, Young Pyo; Kim, Sun Yeou

2013-01-01

213

Direct Analysis in Real Time Mass Spectrometry (DART-MS) Analysis of Skin Metabolome Changes in the Ultraviolet B-Induced Mice.  

PubMed

Ultraviolet (UV) radiation is a major environmental factor that leads to acute and chronic reactions in the human skin. UV exposure induces wrinkle formation, DNA damage, and generation of reactive oxygen species (ROS). Most mechanistic studies of skin physiology and pharmacology related with UV-irradiated skin have focused on proteins and their related gene expression or single- targeted small molecules. The present study identified and analyzed the alteration of skin metabolites following UVB irradiation and topical retinyl palmitate (RP, 5%) treatment in hairless mice using direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) with multivariate analysis. Under the negative ion mode, the DART ion source successfully ionized various fatty acids including palmitoleic and linolenic acid. From DART-TOF-MS fingerprints measured in positive mode, the prominent dehydrated ion peak (m/z: 369, M+H-H2O) of cholesterol was characterized in all three groups. In positive mode, the discrimination among three groups was much clearer than that in negative mode by using multivariate analysis of orthogonal partial-least squares-discriminant analysis (OPLS-DA). DART-TOF-MS can ionize various small organic molecules in living tissues and is an efficient alternative analytical tool for acquiring full chemical fingerprints from living tissues without requiring sample preparation. DART-MS measurement of skin tissue with multivariate analysis proved to be a powerful method to discriminate between experimental groups and to find biomarkers for various experiment models in skin dermatological research. PMID:24404338

Park, Hye Min; Kim, Hye Jin; Jang, Young Pyo; Kim, Sun Yeou

2013-11-01

214

Successful Identification of Clinical Dermatophyte and Neoscytalidium Species by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry  

PubMed Central

Dermatophytes are keratinolytic fungi responsible for a wide variety of diseases of glabrous skin, nails, and hair. Their identification, currently based on morphological criteria, is hindered by intraspecies morphological variability and the atypical morphology of some clinical isolates. The aim of this study was to evaluate matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) as a routine tool for identifying dermatophyte and Neoscytalidium species, both of which cause dermatomycoses. We first developed a spectral database of 12 different species of common and unusual dermatophytes and two molds responsible for dermatomycoses (Neoscytalidium dimidiatum and N. dimidiatum var. hyalinum). We then prospectively tested the performance of the database on 381 clinical dermatophyte and Neoscytalidium isolates. Correct identification of the species was obtained for 331/360 dermatophytes (91.9%) and 18/21 Neoscytalidium isolates (85.7%). The results of MALDI-TOF MS and standard identification disagreed for only 2 isolates. These results suggest that MALDI-TOF MS could be a useful tool for routine and fast identification of dermatophytes and Neoscytalidium spp. in clinical mycology laboratories. PMID:22535981

Alshawa, Kinda; Beretti, Jean-Luc; Lacroix, Claire; Feuilhade, Martine; Dauphin, Brunhilde; Quesne, Gilles; Hassouni, Noura; Nassif, Xavier

2012-01-01

215

Use of ultra-performance liquid chromatography/time-of-flight mass spectrometry with nozzle-skimmer fragmentation for comprehensive quantitative analysis of secondary metabolites in Arabidopsis thaliana.  

PubMed

This study sought to develop techniques for LC/MS-based metabolomics and to verify that an MS/MS spectral tag (MS2T) could be used in practical secondary metabolite profiling. The retention time (RT), precursor ions, and fragment ions generated by nozzle-skimmer fragmentation were determined using ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOF-MS) and compared with the MS2T. A standard mix was analyzed with UPLC/TOF-MS under the same conditions as were used to construct the MS2T. The difference in RT for the standards was less than 0.15 min and the average RSD was about 2.8%, suggesting that the analysis was highly repeatable. Both precursor ions and fragment ions were observed when the cone voltage was 75 V. Experimental data and fragmentation pattern in the MS2T annotation list were highly similar. Wild-type and cas-1 mutant Arabidopsis thaliana samples treated with an elicitor were analyzed using UPLC/TOF-MS. Sixty-five peaks were successfully annotated. Fragment ions were observed with nozzle-skimmer fragmentation in 50 of 65 (77%) peaks. The reliability of annotation may have increased as a result of fragment ions. Results of multivariate analysis suggested that cas-1 was related to induction of the biosynthesis of these flavonoids. The devised method facilitated practical secondary metabolite profiling. PMID:22102342

Sugimoto, Takanori; Bamba, Takeshi; Izumi, Yoshihiro; Nomura, Hironari; Shiina, Takashi; Fukusaki, Eiichiro

2011-12-01

216

Differentiation of Lactobacillus brevis strains using Matrix-Assisted-Laser-Desorption-Ionization-Time-of-Flight Mass Spectrometry with respect to their beer spoilage potential.  

PubMed

Lactobacillus (L.) brevis is one of the most frequently encountered bacteria in beer-spoilage incidents. As the species Lactobacillus brevis comprises strains showing varying ability to grow in beer, ranging from growth in low hopped wheat to highly hopped pilsner beer, differentiation and classification of L. brevis with regard to their beer-spoiling ability is of vital interest for the brewing industry. Matrix-Assisted-Laser-Desorption-Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) has been shown as a powerful tool for species and sub-species differentiation of bacterial isolates and is increasingly used for strain-level differentiation. Seventeen L. brevis strains, representative of different spoilage types, were characterized according to their tolerance to iso-alpha-acids and their growth in wheat-, lager- and pilsner beer. MALDI-TOF MS spectra were acquired to perform strain-level identification, cluster analysis and biomarker detection. Strain-level identification was achieved in 90% out of 204 spectra. Misidentification occurred nearly exclusively among strains belonging to the same spoilage type. Though spectra of strongly beer-spoiling strains showed remarkable similarity, no decisive single markers were detected to be present in all strains of one group. However, MALDI-TOF MS spectra can be reliably assigned to the corresponding strain and thus allow to track single strains and connect them to their physiological properties. PMID:24549193

Kern, Carola C; Vogel, Rudi F; Behr, Jürgen

2014-06-01

217

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

2012-01-01

218

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. PMID:22615938

Pflüger, Valentin; Saad, Maged; Vogel, Guido; Tonolla, Mauro; Perret, Xavier

2012-01-01

219

Matrix-Assisted Laser Desorption/Ionisation, Time-of-Flight Mass Spectrometry in Genomics Research  

PubMed Central

The beginning of this millennium has seen dramatic advances in genomic research. Milestones such as the complete sequencing of the human genome and of many other species were achieved and complemented by the systematic discovery of variation at the single nucleotide (SNP) and whole segment (copy number polymorphism) level. Currently most genomics research efforts are concentrated on the production of whole genome functional annotations, as well as on mapping the epigenome by identifying the methylation status of CpGs, mainly in CpG islands, in different tissues. These recent advances have a major impact on the way genetic research is conducted and have accelerated the discovery of genetic factors contributing to disease. Technology was the critical driving force behind genomics projects: both the combination of Sanger sequencing with high-throughput capillary electrophoresis and the rapid advances in microarray technologies were keys to success. MALDI-TOF MS–based genome analysis represents a relative newcomer in this field. Can it establish itself as a long-term contributor to genetics research, or is it only suitable for niche areas and for laboratories with a passion for mass spectrometry? In this review, we will highlight the potential of MALDI-TOF MS–based tools for resequencing and for epigenetics research applications, as well as for classical complex genetic studies, allele quantification, and quantitative gene expression analysis. We will also identify the current limitations of this approach and attempt to place it in the context of other genome analysis technologies. PMID:16895448

Ragoussis, Jiannis; Elvidge, Gareth P; Kaur, Kulvinder; Colella, Stefano

2006-01-01

220

Application and use of various mass spectrometry methods in clinical microbiology.  

PubMed

When confronted with a septic patient or dealing with an emerging epidemic, clinicians, infection control specialists and microbiologists have often felt an immense 'need for speed' while waiting for culture results. Various mass spectrometry (MS) applications are about to answer most of their demands. Matrix-assisted laser desorption ionization (MALDI) time-of-flight (TOF) MS of whole bacterial cells has already greatly shortened the time needed for identification of a positive culture in major diagnostic laboratories in Europe. MS is described in this article, with a special emphasis on the different systems currently commercially available for routine identification. MALDI-TOF MS remains, however, limited by the previous time-consuming culture steps, and is not suited for strain typing in epidemic contexts. These limitations can be overcome by other applications of MS in microbiology. MALDI-resequencing is a rapid method for genotyping, offering comparable results to multilocus sequence typing. New systems of broad-range PCR, associated with analyses of amplicons by electrospray ionization MS, might allow nearly full automation for the direct identification of pathogens in blood, thus bypassing the culture stage. This article describes various applications of MS methods in clinical microbiology, and provides a comparative table of these technologies. PMID:20969670

Emonet, S; Shah, H N; Cherkaoui, A; Schrenzel, J

2010-11-01

221

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

222

Identification of Coagulase-Negative Staphylococci from Bovine Intramammary Infection by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry  

PubMed Central

Coagulase-negative staphylococci (CoNS) are among the main pathogens causing bovine intramammary infection (IMI) in many countries. However, one of the limitations related to the specific diagnosis of CoNS is the lack of an accurate, rapid, and convenient method that can differentiate the bacterial species comprising this group. The aim of this study was to evaluate the ability of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) to accurately identify CoNS species in dairy cow IMI. In addition, the study aimed to determine the frequency of CoNS species causing bovine IMI. A total of 108 bacterial isolates were diagnosed as CoNS by microbiological cultures from two milk samples collected from 21 dairy herds; the first sample was collected at the cow level (i.e., 1,242 composite samples from all quarters), while the second sample was collected at the mammary quarter level (i.e., 1,140 mammary samples collected from 285 cows). After CoNS isolation was confirmed by microbiological culture for both samples, all CoNS isolates (n = 108) were genotypically differentiated by PCR restriction fragment length polymorphism (RFLP) analysis of a partial groEL gene sequence and subjected to the MALDI-TOF MS identification procedure. MALDI-TOF MS correctly identified 103 (95.4%) of the CoNS isolates identified by PCR-RFLP at the species level. Eleven CoNS species isolated from bovine IMI were identified by PCR-RFLP, and the most prevalent species was Staphylococcus chromogenes (n = 80; 74.1%). In conclusion, MALDI-TOF MS may be a reliable alternative method for differentiating CoNS species causing bovine IMI. PMID:24622096

Gonçalves, Juliano Leonel; Barreiro, Juliana Regina; Braga, Patrícia Aparecida de Campos; Prada e Silva, Luis Felipe; Eberlin, Marcos Nogueira

2014-01-01

223

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. PMID:23840267

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

2013-01-01

224

Simultaneous Quantitative and Qualitative Analysis of Flavonoids from Ultraviolet-B Radiation in Leaves and Roots of Scutellaria baicalensis Georgi Using LC-UV-ESI-Q/TOF/MS.  

PubMed

Scutellaria baicalensis Georgi is one of the most widely used traditional Chinese herbal medicines. It has been used for anti-inflammatory, anticancer, antibacterial activities, and so forth. Long-term enhanced ultraviolet-B (UV-B) radiation caused more effect on leaves than on roots of the plant. Liquid chromatography-ultraviolet detection coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-UV-ESI-Q/TOF/MS) method was applied for simultaneous quantitative and qualitative analysis of flavonoids in leaves and roots of S. baicalensis by enhanced UV-B radiation. Both low-intensity radiation and high-intensity radiation were not significantly increaseing the contents of baicalin, wogonoside, and wogonin in roots. However different intensity of radiation has different effects on several flavonoids in leaves. Both low-intensity radiation and high-intensity radiation had no significant effect on contents of baicalin and tectoridin in leaves; the content of scutellarin was significantly decreased by low-intensity radiation; chrysin was detected in low-intensity radiation and high-intensity radiation, and chrysin content is the highest in low-intensity radiation, but chrysin was not detected in control group. Different changes of different flavonoids under enhanced UV-B radiation indicate that induction on flavonoids is selective by enhanced UV-B radiation. PMID:24757579

Tang, Wen-Ting; Fang, Min-Feng; Liu, Xiao; Yue, Ming

2014-01-01

225

Simultaneous Quantitative and Qualitative Analysis of Flavonoids from Ultraviolet-B Radiation in Leaves and Roots of Scutellaria baicalensis Georgi Using LC-UV-ESI-Q/TOF/MS  

PubMed Central

Scutellaria baicalensis Georgi is one of the most widely used traditional Chinese herbal medicines. It has been used for anti-inflammatory, anticancer, antibacterial activities, and so forth. Long-term enhanced ultraviolet-B (UV-B) radiation caused more effect on leaves than on roots of the plant. Liquid chromatography-ultraviolet detection coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-UV-ESI-Q/TOF/MS) method was applied for simultaneous quantitative and qualitative analysis of flavonoids in leaves and roots of S. baicalensis by enhanced UV-B radiation. Both low-intensity radiation and high-intensity radiation were not significantly increaseing the contents of baicalin, wogonoside, and wogonin in roots. However different intensity of radiation has different effects on several flavonoids in leaves. Both low-intensity radiation and high-intensity radiation had no significant effect on contents of baicalin and tectoridin in leaves; the content of scutellarin was significantly decreased by low-intensity radiation; chrysin was detected in low-intensity radiation and high-intensity radiation, and chrysin content is the highest in low-intensity radiation, but chrysin was not detected in control group. Different changes of different flavonoids under enhanced UV-B radiation indicate that induction on flavonoids is selective by enhanced UV-B radiation. PMID:24757579

Tang, Wen-Ting; Fang, Min-Feng; Liu, Xiao; Yue, Ming

2014-01-01

226

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

227

Characterization of forced degradation products of ketorolac tromethamine using LC/ESI/Q/TOF/MS/MS and in silico toxicity prediction.  

PubMed

Ketorolac, a nonsteroidal anti-inflammatory drug, was subjected to forced degradation studies as per International Conference on Harmonization guidelines. A simple, rapid, precise, and accurate high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (LC/ESI/Q/TOF/MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of ketorolac. The drug was found to degrade in hydrolytic (acidic, basic, and neutral), photolytic (acidic, basic, and neutral solution), and thermal conditions, whereas the solid form of the drug was found to be stable under photolytic conditions. The method has shown adequate separation of ketorolac tromethamine and its degradation products on a Grace Smart C-18 (250?mm?×?4.6?mm i.d., 5?µm) column using 20?mM ammonium formate (pH?=?3.2): acetonitrile as a mobile phase in gradient elution mode at a flow rate of 1.0?ml/min. A total of nine degradation products were identified and characterized by LC/ESI/MS/MS. The most probable mechanisms for the formation of degradation products have been proposed on the basis of a comparison of the fragmentation of the [M?+?H](+) ions of ketorolac and its degradation products. In silico toxicity of the drug and degradation products was investigated by using topkat and derek softwares. The method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per International Conference on Harmonization guidelines. PMID:24809899

Kalariya, Pradipbhai D; Raju, B; Borkar, Roshan M; Namdev, Deepak; Gananadhamu, S; Nandekar, Prajwal P; Sangamwar, Abhay T; Srinivas, R

2014-05-01

228

Nevan Krogan: Mass Spectrometry  

NSDL National Science Digital Library

This lecture from the iBioSeminars project, presented by Nevan Krogan of the Department of Cellular and Molecular Pharmacology at UC-San Francisco, covers mass spectrometry and its application to molecular biology. Mass spectrometry is a powerful tool for elucidating the elemental composition of a sample or molecule. More recently, it has been used to characterize biological material, in particular proteins and protein complexes, in a variety of organisms. This lecture will review the underlying principles of how a mass spectrometer works, discuss up to date instrumentation that is presently being used in the biological research setting and provide specific examples of how mass spectrometry is being used to reveal functional insight into different biological systems. The video runs 27:36 and can be downloaded in a number of formats: QuickTime, MP4, M4V, and PPT. The video can also be streamed through YouTube or iTunes U.

Krogan, Nevan

2013-07-12

229

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

230

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.  

PubMed

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 (MS/MS) in combination with exoglycosidase digestion. The N-linked oligosaccharides were released by treatment with N-glycanase F, reductively aminated with anthranilic acid, and fractionated by normal phase high-performance liquid chromatography (NP-HPLC). The fluorescent-labeled oligosaccharide pool and fractions were analyzed by oMALDI Qq-TOF MS and MS/MS in negative ion mode. Each fraction was further digested with an array of exoglycosidase mixtures, and subsequent MALDI TOF MS analysis of the resulting products yielded information about structural features of the oligosaccharide. The combined data revealed the presence of 21 distinct oligosaccharide structures in cetuximab. These oligosaccharides differ mainly in degree of sialylation with N-glycolyl neuraminic acid and extent of galactosylation (zero-, mono-, di-, and alpha(1-3)-galactosidase). The individual oligosaccharides were further assigned to the specific sites in the Fab and Fc regions of the antibody. This study represents a unique approach in that MS/MS data were used to identify and confirm the oligosaccharide structures of a protein. PMID:17362871

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

2007-05-01

231

Identification of staphylococcal species based on variations in protein sequences (mass spectrometry) and DNA sequence (sodA microarray).  

PubMed

This report is among the first using sequence variation in newly discovered protein markers for staphylococcal (or indeed any other bacterial) speciation. Variation, at the DNA sequence level, in the sodA gene (commonly used for staphylococcal speciation) provided excellent correlation. Relatedness among strains was also assessed using protein profiling using microcapillary electrophoresis and pulsed field electrophoresis. A total of 64 strains were analyzed including reference strains representing the 11 staphylococcal species most commonly isolated from man (Staphylococcus aureus and 10 coagulase negative species [CoNS]). Matrix assisted time of flight ionization/ionization mass spectrometry (MALDI TOF MS) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC ESI MS/MS) were used for peptide analysis of proteins isolated from gel bands. Comparison of experimental spectra of unknowns versus spectra of peptides derived from reference strains allowed bacterial identification after MALDI TOF MS analysis. After LC-MS/MS analysis of gel bands bacterial speciation was performed by comparing experimental spectra versus virtual spectra using the software X!Tandem. Finally LC-MS/MS was performed on whole proteomes and data analysis also employing X!tandem. Aconitate hydratase and oxoglutarate dehydrogenase served as marker proteins on focused analysis after gel separation. Alternatively on full proteomics analysis elongation factor Tu generally provided the highest confidence in staphylococcal speciation. PMID:24184563

Kooken, Jennifer; Fox, Karen; Fox, Alvin; Altomare, Diego; Creek, Kim; Wunschel, David; Pajares-Merino, Sara; Martínez-Ballesteros, Ilargi; Garaizar, Javier; Oyarzabal, Omar; Samadpour, Mansour

2014-02-01

232

Comparison of low molecular weight glutenin subunits identified by SDS-PAGE, 2-DE, MALDI-TOF-MS and PCR in common wheat  

PubMed Central

Background Low-molecular-weight glutenin subunits (LMW-GS) play a crucial role in determining end-use quality of common wheat by influencing the viscoelastic properties of dough. Four different methods - sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2-DE, IEF × SDS-PAGE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR), were used to characterize the LMW-GS composition in 103 cultivars from 12 countries. Results At the Glu-A3 locus, all seven alleles could be reliably identified by 2-DE and PCR. However, the alleles Glu-A3e and Glu-A3d could not be routinely distinguished from Glu-A3f and Glu-A3g, respectively, based on SDS-PAGE, and the allele Glu-A3a could not be differentiated from Glu-A3c by MALDI-TOF-MS. At the Glu-B3 locus, alleles Glu-B3a, Glu-B3b, Glu-B3c, Glu-B3g, Glu-B3h and Glu-B3j could be clearly identified by all four methods, whereas Glu-B3ab, Glu-B3ac, Glu-B3ad could only be identified by the 2-DE method. At the Glu-D3 locus, allelic identification was problematic for the electrophoresis based methods and PCR. MALDI-TOF-MS has the potential to reliably identify the Glu-D3 alleles. Conclusions PCR is the simplest, most accurate, lowest cost, and therefore recommended method for identification of Glu-A3 and Glu-B3 alleles in breeding programs. A combination of methods was required to identify certain alleles, and would be especially useful when characterizing new alleles. A standard set of 30 cultivars for use in future studies was chosen to represent all LMW-GS allelic variants in the collection. Among them, Chinese Spring, Opata 85, Seri 82 and Pavon 76 were recommended as a core set for use in SDS-PAGE gels. Glu-D3c and Glu-D3e are the same allele. Two new alleles, namely, Glu-D3m in cultivar Darius, and Glu-D3n in Fengmai 27, were identified by 2-DE. Utilization of the suggested standard cultivar set, seed of which is available from the CIMMYT and INRA Clermont-Ferrand germplasm collections, should also promote information sharing in the identification of individual LMW-GS and thus provide useful information for quality improvement in common wheat. PMID:20573275

2010-01-01

233

Detection of Large Ions in Time-of-Flight Mass Spectrometry: Effects of Ion Mass and Acceleration Voltage on Microchannel Plate Detector Response  

NASA Astrophysics Data System (ADS)

In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield ? (average number of electrons produced per ion collision) is found to be proportional to mv3.1 (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage.

Liu, Ranran; Li, Qiyao; Smith, Lloyd M.

2014-08-01

234

Detection of large ions in time-of-flight mass spectrometry: effects of ion mass and acceleration voltage on microchannel plate detector response.  

PubMed

In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield ? (average number of electrons produced per ion collision) is found to be proportional to mv(3.1) (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage. PMID:24789774

Liu, Ranran; Li, Qiyao; Smith, Lloyd M

2014-08-01

235

Laser Time-of-Flight Mass Spectrometry for Future In Situ Planetary Missions  

NASA Technical Reports Server (NTRS)

Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) is a versatile, low-complexity instrument class that holds significant promise for future landed in situ planetary missions that emphasize compositional analysis of surface materials. Here we describe a 5kg-class instrument that is capable of detecting and analyzing a variety of analytes directly from rock or ice samples. Through laboratory studies of a suite of representative samples, we show that detection and analysis of key mineral composition, small organics, and particularly, higher molecular weight organics are well suited to this instrument design. A mass range exceeding 100,000 Da has recently been demonstrated. We describe recent efforts in instrument prototype development and future directions that will enhance our analytical capabilities targeting organic mixtures on primitive and icy bodies. We present results on a series of standards, simulated mixtures, and meteoritic samples.

Getty, S. A.; Brinckerhoff, W. B.; Cornish, T.; Ecelberger, S. A.; Li, X.; Floyd, M. A. Merrill; Chanover, N.; Uckert, K.; Voelz, D.; Xiao, X.; Tawalbeh, R.; Glenar, D.; Elsila, J. E.; Callahan, M.

2012-01-01

236

Genomic and proteomic identification of a DNA-binding protein used in the "fingerprinting" of campylobacter species and strains by MALDI-TOF-MS protein biomarker analysis.  

PubMed

We have identified a prominent approximately 10-kDa protein biomarker observed in the matrix-assisted laser desorption/ionization time-of-flight mass spectra (MALDI-TOF-MS) of cell lysates of five thermophilic species of Campylobacter: jejuni, coli, lari, upsaliensis, and helveticus. The biomarker was unambiguously identified by genomic and proteomic sequencing as a DNA-binding protein HU. We report the amino acid sequence of HU as determined by sequencing the hup gene of four species (12 strains): C. jejuni (2), C. coli (4), C. upsaliensis (4) and C. lari(2). Confirmation of the amino acid sequence was obtained by nanoflow high-performance liquid chromatography-tandem mass spectrometry of the tryptic peptides of the extracted/digested HU protein. Protein identification was also confirmed by comparison of the molecular weight (MW) predicted from the hup gene and the MW of HU as measured by high-resolution mass spectrometry. We found the HU protein to be particularly useful as a biomarker in that it strongly ionizes by MALDI and its MW varies between species and among strains within a species. Intra- and interspecies variation of the HU MW is due to changes in the amino acid sequence of the HU protein and not due to co- or posttranslational modifications. The strong ionization efficiency of HU by MALDI is likely due, in part, to four lysine residues clustered at the carboxyl end of the protein. We also report identification of the HU protein biomarker for a C. helveticus strain, whose hup gene was not sequenced, but whose HU amino acid sequence was partially conserved in C. upsaliensis strains. We have also tentatively assigned a approximately 10.5-kDa protein biomarker of a C. concisus strain as an HU protein. PMID:16053303

Fagerquist, Clifton K; Miller, William G; Harden, Leslie A; Bates, Anna H; Vensel, William H; Wang, Guilin; Mandrell, Robert E

2005-08-01

237

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

PubMed

The disulfide-intact and disulfide-reduced ?-subunit of Shiga toxin 2 (?-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 analysis using software developed in-house. E. coli O157:H7 was induced to express Stx2 by culturing on solid agar media supplemented with 10-50 ng mL(-1) of ciprofloxacin (CP). Bacterial cell lysates at each CP concentration were analyzed by MALDI-TOF-MS. A prominent ion at mass-to-charge (m/z) ~7820 was observed for the CP concentration range: 10-50 ng mL(-1), reaching a maximum signal intensity at 20 ng mL(-1). Complex MS/MS data were obtained of the ion at m/z ~7820 by post-source decay resulting in top-down proteomic identification as the mature, signal peptide-removed, disulfide-intact ?-Stx2. Eight fragment ion triplets (each spaced ?m/z ~33 apart) were also observed resulting from backbone cleavage between the two cysteine residues (that form the intra-molecular disulfide bond) and symmetric and asymmetric cleavage of the disulfide bond. The middle fragment ion of each triplet, from symmetric disulfide bond cleavage, was matched to an in silico fragment ion formed from cleavage of the backbone at a site adjacent to an aspartic acid or glutamic acid residue. The flanking fragment ions of each triplet, from asymmetric disulfide bond cleavage, were not matched because their corresponding in silico fragment ions are not represented in the database. Easier to interpret MS/MS data were obtained for the disulfide-reduced ?-Stx2 which resulted in an improved top-down identification. PMID:21336382

Fagerquist, Clifton K; Sultan, Omar

2011-04-21

238

A rapid MALDI-TOF mass spectrometry workflow for Drosophila melanogaster differential neuropeptidomics  

PubMed Central

Background Neuropeptides are a diverse category of signaling molecules in the nervous system regulating a variety of processes including food intake, social behavior, circadian rhythms, learning, and memory. Both the identification and functional characterization of specific neuropeptides are ongoing fields of research. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of nervous tissues from a variety of organisms allows direct detection and identification of neuropeptides. Here, we demonstrate an analysis workflow that allows for the detection of differences in specific neuropeptides amongst a variety of neuropeptides being simultaneously measured. For sample preparation, we describe a straight-forward and rapid (minutes) method where individual adult Drosophila melanogaster brains are analyzed. Using a MATLAB-based data analysis workflow, also compatible with MALDI-TOF mass spectra obtained from other sample preparations and instrumentation, we demonstrate how changes in neuropeptides levels can be detected with this method. Results Over fifty isotopically resolved ion signals in the peptide mass range are reproducibly observed across experiments. MALDI-TOF MS profile spectra were used to statistically identify distinct relative differences in organ-wide endogenous levels of detected neuropeptides between biological conditions. In particular, three distinct levels of a particular neuropeptide, pigment dispersing factor, were detected by comparing groups of preprocessed spectra obtained from individual brains across three different D. melanogaster strains, each of which express different amounts of this neuropeptide. Using the same sample preparation, MALDI-TOF/TOF tandem mass spectrometry confirmed that at least 14 ion signals observed across experiments are indeed neuropeptides. Among the identified neuropeptides were three products of the neuropeptide-like precursor 1 gene previously not identified in the literature. Conclusions Using MALDI-TOF MS and preprocessing/statistical analysis, changes in relative levels of a particular neuropeptide in D. melanogaster tissue can be statistically detected amongst a variety of neuropeptides. While the data analysis methods should be compatible with other sample preparations, the presented sample preparation method was sufficient to identify previously unconfirmed D. melanogaster neuropeptides. PMID:24373546

2013-01-01

239

Multiple-reflection time-of-flight mass spectrometry for in situ applications  

NASA Astrophysics Data System (ADS)

Multiple-reflection time-of-flight mass spectrometers (MR-TOF-MS) have recently been installed at different low-energy radioactive ion beam facilities. They are used as isobar separators with high ion capacity and as mass spectrometers with high mass resolving power and accuracy for short-lived nuclei. Furthermore, MR-TOF-MS have a huge potential for applications in other fields, such as chemistry, biology, medicine, space science, and homeland security. The development, commissioning and results of an MR-TOF-MS is presented, which serves as proof-of-principle to show that very high mass resolving powers (?105) can be achieved in a compact device (length ?30 cm). Based on this work, an MR-TOF-MS for in situ application has been designed. For the first time, this device combines very high mass resolving power (>105), mobility, and an atmospheric pressure inlet in one instrument. It will enable in situ measurements without sample preparation at very high mass accuracy. Envisaged applications of this mobile MR-TOF-MS are discussed.

Dickel, T.; Plaß, W. R.; Lang, J.; Ebert, J.; Geissel, H.; Haettner, E.; Jesch, C.; Lippert, W.; Petrick, M.; Scheidenberger, C.; Yavor, M. I.

2013-12-01

240

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

2012-05-15

241

Mass Processing--An Improved Technique for Protein  

E-print Network

,thus increasing the ability to confidently identify pro- teins with mass spectrometry data. KEY WORDS: peptide-TOF-MS). These instruments allow biologists, whose primary expertise is not in ana- lytical chemistry, to expeditiously" is the term assigned to the peptide molecular weight pro- file obtained with MS after the digestion

Vigoreaux, Jim O.

242

Comparative study of laser induced breakdown spectroscopy and mass spectrometry for the analysis of cultural heritage materials  

NASA Astrophysics Data System (ADS)

Analysis by laser-induced breakdown spectroscopy (LIBS) is compared, on the basis of a hybrid experimental set-up, with laser ablation time-of-flight mass spectrometry (LA-TOF-MS) for the characterization of materials relevant to cultural heritage. The present study focuses on the analysis of selected paint materials such as lithopone, a white inorganic pigment, and two synthetic organic paint formulations, lemon yellow and phthalocyanine blue. Optical emission spectra, obtained by LIBS, lead to rapid, straightforward identification of the elemental content of the paint samples while mass spectra yield, additionally to elemental analysis, complementary isotopic analysis and, more importantly, enable detection of molecules and molecular fragments, permitting a more complete structural and compositional characterization of composite materials. Mass spectra were recorded either simultaneously with the optical emission ones, or sequentially. The latter was preferred for materials having significantly lower fluence threshold for desorption/ionization relative to plasma formation resulting to optimum mass resolution and minimal surface damage. In all, the results of this study demonstrate the advantages of instrumentally complementing LIBS with TOF-MS in relation to applications in cultural heritage materials analysis, with exciting prospects when laser ablation sampling can be carried out under ambient atmosphere.

Kokkinaki, O.; Mihesan, C.; Velegrakis, M.; Anglos, D.

2013-07-01

243

MALDI-TOF MS Imaging of Metabolites with a N-(1-Naphthyl) Ethylenediamine Dihydrochloride Matrix and Its Application to Colorectal Cancer Liver Metastasis.  

PubMed

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a label-free technique for identifying multiplex metabolites and determining both their distribution and relative abundance in situ. Our previous study showed that N-(1-naphthyl) ethylenediamine dihydrochloride (NEDC) could act as a matrix for laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) detection of oligosaccharides in solution. In the present study, NEDC-assisted LDI-TOF MSI yielded many more endogenous compound peaks between m/z 60 and m/z 1600 than 9-aminoacridine (9-AA). Our results show that NEDC-assisted LDI-TOF MSI is especially well-suited for examining distributions of glycerophospholipids (GPs) in addition to low molecular weight metabolites below m/z 400. Particularly, NEDC matrix allowed the LDI-TOF MSI of glucose in animal tissue. Furthermore, NEDC-assisted LDI-TOF MSI was applied to a mouse model of colorectal cancer liver metastasis. We revealed the distinct spatio-molecular signatures of many detected compounds in tumor or tumor-bearing liver, and we found that taurine, glucose, and some GPs decreased in tumor-bearing liver as the tumor developed in liver. Importantly, we also found a glucose gradient in metastatic tumor foci for the first time, which further confirms the energy competition between tumors and liver remnant due to the Warburg effect. Our results suggest that NEDC-assisted LDI MSI provides an in situ label-free analysis of multiple glycerophospholipids and low molecular weight metabolites (including glucose) with abundant peaks and high spatial resolution. This will allow future application to in situ definition of biomarkers, signaling pathways, and disease mechanisms. PMID:25474421

Wang, Jianing; Qiu, Shulan; Chen, Suming; Xiong, Caiqiao; Liu, Huihui; Wang, Jiyun; Zhang, Ning; Hou, Jian; He, Qing; Nie, Zongxiu

2015-01-01

244

FOCUS: TOP-DOWN MASS SPECTROMETRY Collective Mass Spectrometry Approaches  

E-print Network

mediated Bottom Up and electron-transfer dissociation facilitated middle and Top Down mass spectrometry (MSFOCUS: TOP-DOWN MASS SPECTROMETRY Collective Mass Spectrometry Approaches Reveal Broad Bottom Up and Middle Down MS analyses, we find relatively few combinatorially modified forms dominate

Shorter, James

245

Rapid MALDI-TOF MS analysis of bacteriophage major capsid proteins with -mercaptoethanol sample pretreatment  

E-print Network

Rapid MALDI-TOF MS analysis of bacteriophage major capsid proteins with -mercaptoethanol sample Technology Laboratory; Colorado School of Mines, Golden CO 80401 Introduction: ·Bacteriophage (phage bacteriophage -A1122 (which is utilized for plague detection) were analyzed by combining 100µL of phage solution

246

VMSL: Virtual Mass Spectrometry Laboratory  

NSDL National Science Digital Library

This site presents a series of case studies that can be explored using modern mass spectrometry methods. The problem-solving nature of the site provides students a virtual laboratory experience that can supplement access to mass spectrometry instrumentation.

2011-07-05

247

On-line Measurement of Biogenic Volatile Organic Compounds (BVOCs) and Their Oxidation Products by PTR-TOF-MS in a Forest Environment in the Southeastern U.S  

NASA Astrophysics Data System (ADS)

Biogenic volatile organic compounds (BVOCs) including isoprene, monoterpenes, sesquiterpenes and some oxygenated species emitted from vegetation comprise the largest fraction (about 90%) of global non-methane VOC emissions. The Southeastern U.S. experiences very high emissions of biogenic VOCs during the summertime because of high temperatures and heavy local forestation. To further understand the role of biogenic VOCs in shaping local and regional photochemistry, a Proton Transfer Reaction time-of-flight Mass Spectrometry (PTR-TOF-MS) was deployed at a forest site in eastern Tennessee from June 10th to July 16th, 2013 to measure mixing ratios of BVOCs and their oxidation products, as part of the Southern Oxidant and Aerosol Study (SOAS). Isoprene was observed to be the dominant BVOC species at the site, typically reaching a maximum mixing ratio of about 6 ppbv in the early afternoon. Mixing ratios of other biogenic VOCs such as monoterpenes were relatively low (<1ppb). Most of the time, methyl vinyl ketone and methacrolein (MVK+MACR), the major products from OH-initiated isoprene oxidation, tracked well with their precursor. Their mixing ratios typically increased in late morning and maintained relatively high levels in the afternoon and evening before decreasing gradually overnight. The possibility of distinguishing MVK and MACR using NO+ as a reagent ion in the PTR-TOF-MS was also explored. Combined with recent results from laboratory chamber experiments, the ratios between isoprene and its oxidation products are used to understand the oxidation pathways of isoprene in this biogenically-dominated area. Oxygenated VOCs (OVOCs), including formaldehyde and acetone, were also observed at the site. Multi-variate regression analysis of VOC time series is applied to identify contributions from biogenic and anthropogenic emissions and other possible sources, and to understand relationships between primary and secondary compounds in the atmosphere.

Liu, Y.; McKinney, K. A.

2013-12-01

248

Detection of Pancreatic Cancer Biomarkers Using Mass Spectrometry  

PubMed Central

BACKGROUND Pancreatic cancer is the fourth leading cause of cancer-related deaths. Therefore, in order to improve survival rates, the development of biomarkers for early diagnosis is crucial. Recently, diabetes has been associated with an increased risk of pancreatic cancer. The aims of this study were to search for novel serum biomarkers that could be used for early diagnosis of pancreatic cancer and to identify whether diabetes was a risk factor for this disease. METHODS Blood samples were collected from 25 patients with diabetes (control) and 93 patients with pancreatic cancer (including 53 patients with diabetes), and analyzed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF/MS). We performed preprocessing, and various classification methods with imputation were used to replace the missing values. To validate the selection of biomarkers identified in pancreatic cancer patients, we measured biomarker intensity in pancreatic cancer patients with diabetes following surgical resection and compared our results with those from control (diabetes-only) patients. RESULTS By using various classification methods, we identified the commonly splitting protein peaks as m/z 1,465, 1,206, and 1,020. In the follow-up study, in which we assessed biomarkers in pancreatic cancer patients with diabetes after surgical resection, we found that the intensities of m/z at 1,465, 1,206, and 1,020 became comparable with those of diabetes-only patients.

Kim, Kiyoun; Ahn, Soohyun; Lim, Johan; Yoo, Byong Chul; Hwang, Jin-Hyeok; Jang, Woncheol

2014-01-01

249

Enhancing the analysis of mass-spectrometry proteomic profiles using prior knowledge and past data repositories  

E-print Network

-spectrometry proteomic profiling based on SELDI-TOF-MS technology has lead to many promising results in detection. The limitation of the protein identification is that it requires secondary lab-based analysis which increases the cost of the study, and that at the end, the identifications may not lead to any new biologically

Hauskrecht, Milos

250

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

2011-01-01

251

Comparison of matrix-assisted laser desorption ionization-time of flight mass spectrometry and molecular biology techniques for identification of culicoides (Diptera: ceratopogonidae) biting midges in senegal.  

PubMed

Biting midges of the genus Culicoides are implicated as vectors for a wide variety of pathogens. The morphological identification of these arthropods may be difficult because of a lack of detailed investigation of taxonomy for this species in Africa. However, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) profiling is efficient for arthropod identification at the species level. This study established a spectrum database of Culicoides spp. from Senegal using MALDI-TOF. Identification of Culicoides insects to the species level before mass spectrometry was performed on the basis of morphological characters. MALDI-TOF MS reference spectra were determined for 437 field-caught Culicoides of 10 species. The protein profiles of all tested Culicoides revealed several peaks with mass ranges of 2 to 20 kDa. In a validation study, 72 Culicoides specimens in the target species were correctly identified at the species level with a similarity of 95 to 99.9%. Four Culicoides protein profiles were misidentified. Nevertheless, six SuperSpectra (C. imicola, C. enderleini, C. oxystoma, C. kingi, C. magnus, and C. fulvithorax) were created. Abdomens of midges were used to amplify and sequence a portion of the mitochondrial cytochrome oxidase I gene (COI). The results obtained using the MALDI-TOF MS method were consistent with the morphological identification and similar to the genetic identification. Protein profiling using MALDI-TOF is an efficient approach for the identification of Culicoides spp., and it is economically advantageous for approaches that require detailed and quantitative information of vector species that are collected in field. The database of African Culicoides MS spectra created is the first database in Africa. The COI sequences of five Culicoides species that were previously noncharacterized using molecular methods were deposited in GenBank. PMID:25411169

Sambou, Masse; Aubadie-Ladrix, Maxence; Fenollar, Florence; Fall, Becaye; Bassene, Hubert; Almeras, Lionel; Sambe-Ba, Bissoume; Perrot, Nadine; Chatellier, Sonia; Faye, Ngor; Parola, Philippe; Wade, Boubacar; Raoult, Didier; Mediannikov, Oleg

2015-02-01

252

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

2013-01-01

253

[Determination of six plant growth regulator residues in strawberry by liquid chromatography-quadrupole time of flight mass spectrometry].  

PubMed

A novel method was established for the determination of six plant growth regulators (PGRs), 2,4-dichlorophenoxy acetic (2,4-D), 4-chlorophenoxy-acetic acid (CAP), 4-(3-indolyl)-butyric acid (BAA), forchlorfenuron (CPPU), abscisic acid (ABA) and trans-zeatin (ZT) in strawberry using liquid chromatography-quadrupole-time of flight mass spectrometry (LC-Q TOF MS). The Quick, Easy, Cheap, Effective, Rugged and Safe method (QuEChERS) has been validated for the extraction. In this QuEChERS method, the sample was extracted by acetonitrile and cleaned up with C18 adsorbent. The extract was measured directly by LC-Q TOF MS with electrospray ionization in negative mode. The compounds were separated on an Eclipse XDB-C8 column (150 mm x 4.6 mm, 5 microm) with acetonitrile-5 mmol/L ammonium acetate-0. 1% formic acid as mobile phase under gradient elution. The confirmatory analysis was carried out by determining the accurate masses of all compounds and fragment ions upon Target MS/MS. The limits of detection (LODs) were between 1 microg/kg and 5 microg/kg. The linear range was 0.005-1.0 mg/L for each analyte. The recoveries ranged from 87% to 107% with the relative standard deviations (RSDs) less than 10% (n = 6). The method was proved to be simple and accurate. PMID:23383488

Liu, Jingjing; Gong, Ping; Zhang, Xiaomei; Wang, Jianhua; Wang, Jingtang

2012-10-01

254

Mass Spectrometric Analysis of Lipopeptide from Bacillus Strains Isolated from Diverse Geographical Locations  

Technology Transfer Automated Retrieval System (TEKTRAN)

Matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF MS) has been applied to characterize lipopeptide biomarkers from 54 different strains of Bacillis from most taxa within the B. subtilis - B. licheniformis clade, isolated from 7 different geographic locations on ...

255

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

256

Study of the determination and pharmacokinetics of bufadienolides in dog's plasma after administration of Liu-Shen-Wan by high performance liquid chromatography time-of-flight mass spectrometry.  

PubMed

A sensitive and reliable high performance liquid chromatography-tandem time-of-flight mass spectrometry method (HPLC/TOF MS) has been developed to determine three active bufadienolides from Liu-Shen-Wan (LSW) in dog's plasma. Enhanced selectivity and sensitivity in comparison with traditional HPLC/DAD method could be obtained through this method. Bufodienolides could be well separated and distinguished from its nominally isobaric endogenous components by HPLC/TOF MS, with the linear calibration range covering from 0.5 ng/mL to 100 ng/mL and Limit of Detection (LOD) being about 0.15 ng/mL. This method was also proved to be quite stable, with the intra-day precision and the inter-day precision results being lower than 6.39% and 7.44%, respectively. Meanwhile HPLC/TOF MS was successfully used in the pharmacokinetic study of LSW. For resibufogenin, the major pharmacokinetic parameters AUC0-t, Cmax and t1/2alpha were 160.72+/-21.97 ng/mL min, 2.35+/-0.71 ng/mL and 20.74+/-5.89 min, respectively, and for bufalin the corresponding parameters were 55.55+/-7.55 ng/mL min, 0.91+/-0.15 ng/mL and 25.45+/-13.28 min, respectively. PMID:17481974

Cao, Yang; Zhao, Lvlong; Liang, Qionglin; Bi, Kaishun; Wang, Yiming; Luo, Guoan

2007-06-15

257

Mass Spectrometry and Biotechnology Resource  

NSDL National Science Digital Library

Ionsource is a website that provides access to an index of resources including tutorials, links to downloadable sites, jobs and conference information involving mass spectrometry and biotechnology subjects. Examples of tutorials include lessons on atomic mass and amino acid residue mass. For a review of mass spectrometry or biotechnology or for an introduction, this site provides a well-rounded source of information.

2007-01-11

258

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry applied to virus identification  

PubMed Central

Virus detection and/or identification traditionally rely on methods based on cell culture, electron microscopy and antigen or nucleic acid detection. These techniques are good, but often expensive and/or time-consuming; furthermore, they not always lead to virus identification at the species and/or type level. In this study, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was tested as an innovative tool to identify human polioviruses and to identify specific viral protein biomarkers in infected cells. The results revealed MALDI-TOF MS to be an effective and inexpensive tool for the identification of the three poliovirus serotypes. The method was firstly applied to Sabin reference strains, and then to isolates from different clinical samples, highlighting its value as a time-saving, sensitive and specific technique when compared to the gold standard neutralization assay and casting new light on its possible application to virus detection and/or identification. PMID:25354905

Calderaro, Adriana; Arcangeletti, Maria-Cristina; Rodighiero, Isabella; Buttrini, Mirko; Gorrini, Chiara; Motta, Federica; Germini, Diego; Medici, Maria-Cristina; Chezzi, Carlo; De Conto, Flora

2014-01-01

259

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry applied to virus identification.  

PubMed

Virus detection and/or identification traditionally rely on methods based on cell culture, electron microscopy and antigen or nucleic acid detection. These techniques are good, but often expensive and/or time-consuming; furthermore, they not always lead to virus identification at the species and/or type level. In this study, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was tested as an innovative tool to identify human polioviruses and to identify specific viral protein biomarkers in infected cells. The results revealed MALDI-TOF MS to be an effective and inexpensive tool for the identification of the three poliovirus serotypes. The method was firstly applied to Sabin reference strains, and then to isolates from different clinical samples, highlighting its value as a time-saving, sensitive and specific technique when compared to the gold standard neutralization assay and casting new light on its possible application to virus detection and/or identification. PMID:25354905

Calderaro, Adriana; Arcangeletti, Maria-Cristina; Rodighiero, Isabella; Buttrini, Mirko; Gorrini, Chiara; Motta, Federica; Germini, Diego; Medici, Maria-Cristina; Chezzi, Carlo; De Conto, Flora

2014-01-01

260

Identification of metabolites of fosinopril produced by human and rat liver microsomes with liquid chromatography-mass spectrometry.  

PubMed

Metabolic profiles of prodrug fosinopril and pharmacologically active metabolite fosinoprilat were studied using human or rat liver microsomes and S9 fractions. Metabolites were identified by ultra high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) using electrospray ionization in the positive and negative ion mode. They were characterized by accurate MS and MS/MS spectra and based on their different fragmentation pathways. With human liver microsomes fosinopril was metabolized via hydroxylation, glucuronidation, and hydrolysis to fosinoprilat. As expected the main metabolite was fosinoprilat and it was further hydroxylated and glucuronidated. However, these metabolites were not detected after incubation of fosinoprilat with human liver microsomes, indicating that metabolic reactions occur in sequence and fosinopril is hydrolyzed after glucuronidation or hydroxylation. With the developed UHPLC/Q-TOF-MS method once or twice hydroxylated fosinopril metabolites were detected for the first time and different regioisomers were separated. It was observed that the hydrolysis of fosinopril to fosinoprilat was more efficient with rat than with human liver microsomes, and therefore more hydroxylated fosinoprilat metabolites were detected when rat liver microsomes were used. Glucuronidation of fosinopril was not observed with rat liver microsomes. PMID:24365260

Uutela, Päivi; Monto, Matti; Iso-Mustajärvi, Ilona; Madetoja, Mari; Yliperttula, Marjo; Ketola, Raimo A

2014-03-12

261

Untargeted Metabolomic Profiling of Amphenicol-Resistant Campylobacter jejuni by Ultra-High-Performance Liquid Chromatography-Mass Spectrometry.  

PubMed

Campylobacter jejuni, an important foodborne microorganism, poses severe and emergent threats to human health as antibiotic resistance becomes increasingly prevalent. The mechanisms of drug resistance are hard to decipher, and little is known at the metabolic level. Here we apply metabolomic profiling to discover metabolic changes associated with amphenicol (chloramphenicol and florfenicol) resistance mutations of Campylobacter jejuni. An optimized sample preparation method was combined with ultra-high-performance liquid chromatography-time-of-flight mass spectrometry (UHPLC-TOF/MS) and pattern recognition for the analysis of small-molecule biomarkers of drug resistance. UHPLC-triple quadrupole MS operated in multiple reaction monitoring mode was used for quantitative analysis of metabolic features from UHPLC-TOF/MS profiling. Up to 41 differential metabolites involved in glycerophospholipid metabolism, sphingolipid metabolism, and fatty acid metabolism were observed in a chloramphenicol-resistant mutant strain of Campylobacter jejuni. A panel of 40 features was identified in florfenicol-resistant mutants, demonstrating changes in glycerophospholipid metabolism, sphingolipid metabolism, and tryptophan metabolism. This study shows that the UHPLC-MS-based metabolomics platform is a promising and valuable tool to generate new insights into the drug-resistant mechanism of Campylobacter jejuni. PMID:25491530

Li, Hui; Xia, Xi; Li, Xiaowei; Naren, Gaowa; Fu, Qin; Wang, Yang; Wu, Congming; Ding, Shuangyang; Zhang, Suxia; Jiang, Haiyang; Li, Jiancheng; Shen, Jianzhong

2015-02-01

262

Identification of Leishmania at the species level with matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

Matrix-assisted laser desorption ionization time-of-flightMALDI-TOF mass spectrometry (MS) is now widely recognized as a powerful tool with which to identify bacteria and fungi at the species level, and sometimes in a rapid and accurate manner. We report herein an approach to identify, at the species level, Leishmania promastigotes from in vitro culture. We first constructed a reference database of spectra including the main Leishmania species known to cause human leishmaniasis. Then, the performance of the reference database in identifying Leishmania promastigotes was tested on a panel of 69 isolates obtained from patients. Our approach correctly identified 66 of the 69 isolates tested at the species level with log (score) values superior to 2. Two Leishmania isolates yielded non-interpretable MALDI-TOF MS patterns, owing to low log (score) values. Only one Leishmania isolate of Leishmania peruviana was misidentified as the closely related species Leishmania braziliensis, with a log (score) of 2.399. MALDI-TOF MS is a promising approach, providing rapid and accurate identification of Leishmania from in vitro culture at the species level. PMID:24165542

Cassagne, C; Pratlong, F; Jeddi, F; Benikhlef, R; Aoun, K; Normand, A-C; Faraut, F; Bastien, P; Piarroux, R

2014-06-01

263

Isotope Ratio Mass Spectrometry.  

PubMed

Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic, chemical, and biological origins of substances. The ability to determine the source of an organic substance stems from the relative isotopic abundances of the elements which comprise the material. Because the isotope ratios of elements such as carbon, hydrogen, oxygen, sulfur, and nitrogen can become locally enriched or depleted through a variety of kinetic and thermodynamic factors, measurement of the isotope ratios can be used to differentiate between samples which otherwise share identical chemical compositions. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. Here, highlights of advances in instrumentation and applications within the last three years are provided to illustrate the impact of this rapidly growing area of research. Some prominent new applications include authenticating organic food produce, ascertaining whether or not African elephants are guilty of night-time raids on farmers' crops, and linking forensic drug and soil samples from a crime scene to a suspected point of origin. For the sake of brevity, we focus this Minireview on the isotope ratio measurements of lighter-elements common to organic sources; we do not cover the equally important field of inorganic isotope ratio mass spectrometry. PMID:19173039

Muccio, Zeland; Jackson, Glen P

2009-02-01

264

Mass Spectrometry of Glycans  

PubMed Central

Powerful new strategies based on mass spectrometry are revolutionizing the structural analysis and profiling of glycans and glycoconjugates. We survey here the major biosynthetic pathways that underlie the biological diversity in glycobiology, with emphasis on glycoproteins, and the approaches that can be used to address the resulting heterogeneity. Included among these are derivatizations, on- and off-line chromatography, electrospray and matrix-assisted laser desorption/ionization, and a variety of dissociation methods, the recently introduced electron-based techniques being of particular interest. PMID:24010834

Han, Liang; Costello, Catherine E.

2014-01-01

265

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. PMID:22207568

Sides, Cynthia R.; Liyanage, Rohana; Lay, Jackson O.; Philominathan, Sagaya Theresa Leena; Matsushita, Osamu; Sakon, Joshua

2012-01-01

266

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

PubMed

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 the different extraction methods such as solid phase material, sample pH and elution solvent in the case of SPE; the type and volume of the extracting and dispersive solvent, pH of sample, salt addition and number of extraction steps in the case of DLLME; and the stirring time, pH of sample, sample volume and salt addition for SBSE were evaluated. SPE allowed the best recoveries for most of the analytes. Pravastatin was poorly extracted by DLLME and could not be determined. SBSE was only applicable for lovastatin and simvastatin. However, despite the limitations of having poorer recovery than SPE, DLLME and SBSE offered some advantages because they are simple, require low organic solvent volumes and present low matrix effects. DLLME required less time of analysis, and for SBSE the stir-bar was re-usable. SPE, DLLME and SBSE provided method detection limits in the range of 0.04-11.2 ng L(-1), 0.10-17.0 ng L(-1) for 0.52-2.00 ng L(-1), respectively, in real samples. To investigate and compare their applicability, SPE, DLLME and SBSE procedures were applied to the detection of statin drugs in effluent wastewater and river samples. PMID:21645748

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

2011-07-15

267

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

268

Single event mass spectrometry  

DOEpatents

A means and method for single event time of flight mass spectrometry for analysis of specimen materials. The method of the invention includes pulsing an ion source imposing at least one pulsed ion onto the specimen to produce a corresponding emission of at least one electrically charged particle. The emitted particle is then dissociated into a charged ion component and an uncharged neutral component. The ion and neutral components are then detected. The time of flight of the components are recorded and can be used to analyze the predecessor of the components, and therefore the specimen material. When more than one ion particle is emitted from the specimen per single ion impact, the single event time of flight mass spectrometer described here furnis This invention was made with Government support under Contract No. W-7405-ENG82 awarded by the Department of Energy. The Government has certain rights in the invention.

Conzemius, Robert J. (Ames, IA)

1990-01-16

269

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

270

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

271

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 modeled 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. The monoterpene emission (in mg compound m-2) during this measurement period is underestimated by 40% if the effect of 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.

2013-12-01

272

Speciation of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis by matrix-assisted laser desorption ionization-time of flight mass spectrometry.  

PubMed

Multiple strains of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis isolated from animal, clinical, or food samples have been analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Whole bacterial cells were harvested from colonies or confluent growth on agar and transferred directly into solvent and then to a spot of dried 3-methoxy-4-hydroxycinnamic acid (matrix). Multiple ions in the 5,000- to 15,000-Da mass range were evident in spectra for each strain; one or two ions in the 9,500- to 11,000-Da range were consistently high intensity. "Species-identifying" biomarker ions (SIBIs) were evident from analyses of multiple reference strains for each of the six species, including the genome strains C. jejuni NCTC 11168 and C. jejuni RM1221. Strains grown on nine different combinations of media and atmospheres yielded SIBI masses within +/-5 Da with external instrument calibration. The highest-intensity C. jejuni SIBIs were cytosolic proteins, including GroES, HU/HCj, and RplL. Multiple intraspecies SIBIs, corresponding probably to nonsynonymous nucleotide polymorphisms, also provided some intraspecies strain differentiation. MALDI-TOF MS analysis of 75 additional Campylobacter strains isolated from humans, poultry, swine, dogs, and cats revealed (i) associations of SIBI type with source, (ii) strains previously speciated incorrectly, and (iii) "strains" composed of more than one species. MALDI-TOF MS provides an accurate, sensitive, and rapid method for identification of multiple Campylobacter species relevant to public health and food safety. PMID:16204551

Mandrell, Robert E; Harden, Leslie A; Bates, Anna; Miller, William G; Haddon, William F; Fagerquist, Clifton K

2005-10-01

273

The value of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in identifying clinically relevant bacteria: a comparison with automated microbiology system  

PubMed Central

Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been developed as a new-type soft ionization mass spectrometry in the recent year. Increasing number of clinical microbiological laboratories consider it as an innovate approach for bacterial identification. Methods A total of 876 clinical strains, comprising 52 species in 27 genus, were obtained from Fudan University Affiliated Zhongshan Hospital. We compared the identification accuracy of the Vitek MS system (bioMerieux, Marcy l’Etoile) to other conventional methods for bacterial identification. 16S rRNA gene sequencing was performed as a reference identification method in cases of discrepant results. Results The Vitek MS system consistently produced accurate results within minutes of loading, while conventional methods required several hours to produce identification results. Among the 876 isolates, the overall performance of Vitek MS was significantly better than the conventional method both for correct species identification (830, 94.7% vs. 746, 85.2%, respectively, P=0.000). Conclusions Compared to traditional identification methods, MALDI-TOF MS is a rapid, accurate and economical technique to enhance the clinical value of microorganism identification. PMID:24822117

Zhou, Chunmei; Huang, Shenglei; Shan, Yuzhang; Ye, Xiangru

2014-01-01

274

Synthesis of polydopamine-coated magnetic graphene for Cu(2+) immobilization and application to the enrichment of low-concentration peptides for mass spectrometry analysis.  

PubMed

In this work, Cu(2+)-immobilized magnetic graphene@polydopamine (magG@PDA@Cu(2+)) composites were synthesized for the first time. Magnetic graphene prepared via a hydrothermal reaction were easily encapsulated by a layer of polydopamine through the oxidative polymerization of dopamine in alkaline buffer, and it was conveniently modified with Cu(2+) ions afterward. The as-prepared magG@PDA@Cu(2+) composites were endowed with strong magnetic responsivness, excellent dispersibility and biological compatibility. We applied the novel nanocomposites to the enrichment and identification of low-concentration standard peptides, peptides in standard protein digestions, endogenous peptides in human urine and serum. The enriched peptides were eluted and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The magG@PDA@Cu(2+) composites were proved to exhibit great affinity to both hydrophobic and hydrophilic peptides, thus providing a rapid and facile approach to the extraction of low-concentration peptides. Notably, peptides at an extremely low concentration of 10 pM could be detected by MALDI-TOF MS after enrichment with magG@PDA@Cu(2+) composites. The results demonstrated that the magG@PDA@Cu(2+) composite is a promising candidate for the enrichment of low-abundance peptides for mass spectrometry analysis. PMID:24281731

Zhao, Man; Deng, Chunhui; Zhang, Xiangmin

2013-12-26

275

Evaluation of the Andromas Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Aerobically Growing Gram-Positive Bacilli  

PubMed Central

Matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a rapid and simple microbial identification method. Previous reports using the Biotyper system suggested that this technique requires a preliminary extraction step to identify Gram-positive rods (GPRs), a technical issue that may limit the routine use of this technique to identify pathogenic GPRs in the clinical setting. We tested the accuracy of the MALDI-TOF MS Andromas strategy to identify a set of 659 GPR isolates representing 16 bacterial genera and 72 species by the direct colony method. This bacterial collection included 40 C. diphtheriae, 13 C. pseudotuberculosis, 19 C. ulcerans, and 270 other Corynebacterium isolates, 32 L. monocytogenes and 24 other Listeria isolates, 46 Nocardia, 75 Actinomyces, 18 Actinobaculum, 11 Propionibacterium acnes, 18 Propionibacterium avidum, 30 Lactobacillus, 21 Bacillus, 2 Rhodococcus equi, 2 Erysipelothrix rhusiopathiae, and 38 other GPR isolates, all identified by reference techniques. Totals of 98.5% and 1.2% of non-Listeria GPR isolates were identified to the species or genus level, respectively. Except for L. grayi isolates that were identified to the species level, all other Listeria isolates were identified to the genus level because of highly similar spectra. These data demonstrate that rapid identification of pathogenic GPRs can be obtained without an extraction step by MALDI-TOF mass spectrometry. PMID:22692743

Farfour, E.; Leto, J.; Barritault, M.; Barberis, C.; Meyer, J.; Dauphin, B.; Le Guern, A.-S.; Leflèche, A.; Badell, E.; Guiso, N.; Leclercq, A.; Le Monnier, A.; Lecuit, M.; Rodriguez-Nava, V.; Bergeron, E.; Raymond, J.; Vimont, S.; Bille, E.; Carbonnelle, E.; Guet-Revillet, H.; Lécuyer, H.; Beretti, J.-L.; Vay, C.; Berche, P.; Ferroni, A.; Nassif, X.

2012-01-01

276

Reprint of "Identification of staphylococcal species based on variations in protein sequences (mass spectrometry) and DNA sequence (sodA microarray)".  

PubMed

This report is among the first using sequence variation in newly discovered protein markers for staphylococcal (or indeed any other bacterial) speciation. Variation, at the DNA sequence level, in the sodA gene (commonly used for staphylococcal speciation) provided excellent correlation. Relatedness among strains was also assessed using protein profiling using microcapillary electrophoresis and pulsed field electrophoresis. A total of 64 strains were analyzed including reference strains representing the 11 staphylococcal species most commonly isolated from man (Staphylococcus aureus and 10 coagulase negative species [CoNS]). Matrix assisted time of flight ionization/ionization mass spectrometry (MALDI TOF MS) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC ESI MS/MS) were used for peptide analysis of proteins isolated from gel bands. Comparison of experimental spectra of unknowns versus spectra of peptides derived from reference strains allowed bacterial identification after MALDI TOF MS analysis. After LC-MS/MS analysis of gel bands bacterial speciation was performed by comparing experimental spectra versus virtual spectra using the software X!Tandem. Finally LC-MS/MS was performed on whole proteomes and data analysis also employing X!tandem. Aconitate hydratase and oxoglutarate dehydrogenase served as marker proteins on focused analysis after gel separation. Alternatively on full proteomics analysis elongation factor Tu generally provided the highest confidence in staphylococcal speciation. PMID:24486297

Kooken, Jennifer; Fox, Karen; Fox, Alvin; Altomare, Diego; Creek, Kim; Wunschel, David; Pajares-Merino, Sara; Martínez-Ballesteros, Ilargi; Garaizar, Javier; Oyarzabal, Omar; Samadpour, Mansour

2014-01-01

277

Analysis of complex phthalic acid based polyesters by the combination of size exclusion chromatography and matrix-assisted laser desorption/ionization mass spectrometry.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used in conjunction with size exclusion chromatography (SEC) to investigate a model polyester system based on phthalic anhydride-1,2-propylene glycol. The polyesters were synthesized with a 30% molar excess of glycol, with kinetic samples being removed during different intervals of the polyesterification reaction. SEC was used to track the course of the reaction by determining the molecular weight and molecular weight distributions before subsequent off-line coupling with MALDI-TOF MS as a selective detection method to determine the chemical composition, identify the functionality type distributions as well as assist in assigning structural conformations. Mass spectrometry analysis proved to be a highly effective tool to facilitate the identification of the narrowly dispersed fractions obtained from the chromatographic separations as well as serve as a core method to investigate the heterogeneous nature of the bulk kinetic samples. Through the hyphenation of these sophisticated polymer characterization techniques, information on the molecular heterogeneity of the model polyesters, showing a complex variety of possible distributions, was obtained. PMID:24370096

Pretorius, Nadine O; Rode, Karsten; Simpson, Jaylin M; Pasch, Harald

2014-01-15

278

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

2011-11-01

279

Potential of gas chromatography-atmospheric pressure chemical ionization-time-of-flight mass spectrometry for the determination of sterols in human plasma.  

PubMed

The application of Gas Chromatography (GC)-Atmospheric Pressure Chemical Ionization (APCI)-Time-of-Flight Mass Spectrometry (TOF-MS) is presented for sterol analysis in human plasma. A commercial APCI interface was modified to ensure a well-defined humidity which is essential for controlled ionization. In the first step, optimization regarding flow rates of auxiliary gases was performed by using a mixture of model analytes. Secondly, the qualitative and quantitative analysis of sterols including oxysterols, cholesterol precursors, and plant sterols as trimethylsilyl-derivatives was successfully carried out. The characteristics of APCI together with the very good mass accuracy of TOF-MS data enable the reliable identification of relevant sterols in complex matrices. Linear calibration lines and plausible results for healthy volunteers and patients could be obtained whereas all mass signals were extracted with an extraction width of 20 ppm from the full mass data set. One advantage of high mass accuracy can be seen in the fact that from one recorded run any search for m/z can be performed. PMID:24463103

Matysik, S; Schmitz, G; Bauer, S; Kiermaier, J; Matysik, F-M

2014-04-11

280

Evaluation of matrix-assisted laser desorption/ionization mass spectrometry for second-generation lignin analysis.  

PubMed

Matrix-Assisted Laser Desorption/Ionization time-of-flight (MALDI-TOF) mass spectrometry is evaluated as an elucidation tool for structural features and molecular weights estimation of some extracted herbaceous lignins. Optimization of analysis conditions, using a typical organic matrix, namely ?-cyano-4-hydroxycinnamic acid (CHCA), in combination with ?-cyclodextrin, allows efficient ionization of poorly soluble lignin materials and suppression of matrix-related ions background. Analysis of low-mass fragments ions (m/z 100-600) in the positive ion mode offers a "fingerprint" of starting lignins that could be a fine strategy to qualitatively identify principal inter-unit linkages between phenylpropanoid units. The molecular weights of lignins are estimated using size exclusion chromatography and compared to MALDI-TOF-MS profiles. Miscanthus (Miscanthus x giganteus) and Switchgrass (Panicum Virgatum L.) lignins, recovered after a formic acid/acetic acid/water process or aqueous ammonia soaking, are selected as benchmarks for this study. PMID:23300342

Richel, Aurore; Vanderghem, Caroline; Simon, Mathilde; Wathelet, Bernard; Paquot, Michel

2012-01-01

281

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

2013-03-27

282

Evaluation of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for Second-Generation Lignin Analysis  

PubMed Central

Matrix-Assisted Laser Desorption/Ionization time-of-flight (MALDI-TOF) mass spectrometry is evaluated as an elucidation tool for structural features and molecular weights estimation of some extracted herbaceous lignins. Optimization of analysis conditions, using a typical organic matrix, namely ?-cyano-4-hydroxycinnamic acid (CHCA), in combination with ?-cyclodextrin, allows efficient ionization of poorly soluble lignin materials and suppression of matrix-related ions background. Analysis of low-mass fragments ions (m/z 100–600) in the positive ion mode offers a “fingerprint” of starting lignins that could be a fine strategy to qualitatively identify principal inter-unit linkages between phenylpropanoid units. The molecular weights of lignins are estimated using size exclusion chromatography and compared to MALDI-TOF-MS profiles. Miscanthus (Miscanthus x giganteus) and Switchgrass (Panicum Virgatum L.) lignins, recovered after a formic acid/acetic acid/water process or aqueous ammonia soaking, are selected as benchmarks for this study. PMID:23300342

Richel, Aurore; Vanderghem, Caroline; Simon, Mathilde; Wathelet, Bernard; Paquot, Michel

2012-01-01

283

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

284

Investigating isoprene photo-oxidation at low-NOx conditions using PTR-TOF-MS  

NASA Astrophysics Data System (ADS)

Recent studies have shown that gas-phase isoprene chemistry plays an important role in the formation of secondary organic aerosol as well as in HOx radical recycling, but many uncertainties remain in the mechanisms governing these processes. Photo-oxidation of isoprene was investigated in the Harvard Environmental Chamber at steady-state mode using H2O2 as the primary HOx source. The concentrations of isoprene, H2O2 and NO, with typical values of 10-80 ppb, 10 ppm, and <0.15 ppb, respectively, were precisely controlled such that the isoprene peroxy radical chemistry was dominated by the HO2 pathway. There are few other laboratory studies that specifically probe this reaction channel, which is important in remote regions of the atmosphere with low NOx levels. A proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) equipped with switchable reagent ion capability (SRI, including H3O+, NO+ and O2+) was used to measure isoprene and its oxidation products. Isomeric ketones and aldehydes, such as the two major isoprene oxidation products methyl vinyl ketone (MVK, C4H6O) and methacrolein (MAC, C4H6O), which cannot be separated using the normal H3O+ ionization, were successfully differentiated using NO+ at optimized drift tube conditions. The NO+ ion reacted with MAC to give mainly dehydrogenated cations C4H5O+ and a small amount of C4H6O.NO+ cluster ions, whereas it reacted with MVK to give only C4H6O.NO+ cluster ions. This feature was used to separately quantify MVK and MAC yields from isoprene oxidation. Since the production of MVK and MAC via the HO2 pathway may be accompanied by HOx recycling, the quantified yields of MVK and MAC are valuable for understanding possible HOx recycling mechanisms in remote regions of the atmosphere with low NOx levels. The extensive information on molecular formulas and chemical functionality provided by the TOF and SRI capabilities is also being used to facilitate the identification of other oxidation products of isoprene.

Liu, Y.; Martin, S. T.; McKinney, K. A.

2011-12-01

285

Leptospira species and serovars identified by MALDI-TOF mass spectrometry after database implementation  

PubMed Central

Background Leptospirosis, a spirochaetal zoonotic disease of worldwide distribution, endemic in Europe, has been recognized as an important emerging infectious disease, though yet it is mostly a neglected disease which imparts its greatest burden on impoverished populations from developing countries. Leptospirosis is caused by the infection with any of the more than 230 serovars of pathogenic Leptospira sp. In this study we aimed to implement the MALDI-TOF mass spectrometry (MS) database currently available in our laboratory with Leptospira reference pathogenic (L. interrogans, L. borgpetersenii, L. kirschneri, L. noguchii), intermediate (L. fainei) and saprophytic (L. biflexa) strains of our collection in order to evaluate its possible application to the diagnosis of leptospirosis and to the typing of strains. This was done with the goal of understanding whether this methodology could be used as a tool for the identification of Leptospira strains, not only at species level for diagnostic purposes, but also at serovar level for epidemiological purposes, overcoming the limits of serological and molecular conventional methods. Twenty Leptospira reference strains were analysed by MALDI-TOF MS. Statistical analysis of the protein spectra was performed by ClinProTools software. Results The spectra obtained by the analysis of the reference strains tested were grouped into 6 main classes corresponding to the species analysed, highlighting species-specific protein profiles. Moreover, the statistical analysis of the spectra identified discriminatory peaks to recognize Leptospira strains also at serovar level extending previously published data. Conclusions In conclusion, we confirmed that MALDI-TOF MS could be a powerful tool for research and diagnostic in the field of leptospirosis with broad applications ranging from the detection and identification of pathogenic leptospires for diagnostic purposes to the typing of pathogenic and non-pathogenic leptospires for epidemiological purposes in order to enrich our knowledge about the epidemiology of the infection in different areas and generate control strategies. PMID:24890024

2014-01-01

286

Matrix-Assisted Laser Desorption Ionization: Time of Flight Mass Spectrometry-Identified Models for Detection of ESBL-Producing Bacterial Strains  

PubMed Central

Background The increase in the amount of extended spectrum beta-lactamases (ESBL)-producing gram-negative bacteria is seriously threatening human health in recent years. Therefore, it is necessary to develop a rapid and reliable method for identification of ESBLs. The purpose of this study was to establish a novel method to discriminate between ESBL-producing and non- ESBL-producing bacteria by using the matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) technique. Material/Methods We detected hydrolyzed production of cefotaxime after incubation with 69 gram-negative bacteria by using MALDI-TOF-MS. Then we established genetic algorithm (GA), supervised neural networks (SNN), and quick classifier (QC) models using several peaks to identify ESBL-producing strains. To confirm the clinical applicability of the models established, a blinded validation test was performed in 34 clinical isolated strains. Results Using ClinPro Tools software, we identified 4 peaks (456 Da, 396 Da, 370 Da, and 371 Da) in mass spectra of cefotaxime solution that have high enough specificity to discriminate ESBL-producing from non- ESBL-producing strains. Recognition capability of models established were 97.5% (GA), 92.5% (SNN), and 92.5% (QC), and cross validation rates were 90.15% (GA), 97.62 (SNN), and 97.62% (QC). The accuracy rates of the blinded validation test were 82.4% (GA), 88.2% (SNN), and 82.4% (QC). Conclusions Our results demonstrate that identification of ESBLs strains by MALDI-TOF-MS has potential clinical value and could be widely used in the future as a routine test in clinical microbiology laboratories. PMID:25390932

Li, Bo; Guo, Tongsheng; Qu, Fen; Li, Boan; Wang, Haibin; Sun, Zhiqiang; Li, Xiaohan; Gao, Zhiqiang; Bao, Chunmei; Zhang, Chenglong; Li, Xiaoxi; Mao, Yuanli

2014-01-01

287

Mass spectrometry in ionospheric research.  

PubMed

Mass spectrometry played a key role in the development of the understanding of the earth's ionosphere. Of primary importance was its use for in situ atmospheric measurements of the ion and neutral composition of the atmosphere. Mass spectrometry has also played an essential role in the laboratory measurement of critical ionospheric molecular processes. Examples of both are given. PMID:17099890

Ferguson, Eldon E

2007-01-01

288

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

Complementary methods using liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-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-beta-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 <500nM), were more effectively analyzed by GCxGC-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 139.3nM). The overlap between the LC-based and GC-based methods of seven 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. PMID:19268957

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

2009-04-10

289

Inorganic mass spectrometry  

SciTech Connect

Inorganic mass spectrometry is enjoying a resurgence of interest among analytical chemists. Dramatic improvements in existing techniques, rapid development and commercialization of new methods, and successful application to increasingly difficult analytical problems are all factors responsible for the renewal of interest in MS as applied to inorganic, elemental, and isotopic analysis. Given the level of recent activity in this field, the book is both timely and needed. Edited by three faculty members of the University of Antwerp in Belgium, the book contains chapters contributed by these editors and other established mass spectrometrists. It fills a void that has existed too long in MS. Too many recent texts purporting to survey the technique of MS in general have ignored inorganic applications altogether. As the title implies, this book turns the tables somewhat and is devoted entirely to the importance of MS in inorganic analysis. The book contains detailed chapters on both established and newer methods of inorganic MS analysis, including spark source, glow discharge, secondary ion, laser microprobe, ICP source, and isotope dilution MS techniques. Introductory and concluding chapters discuss the historical and future roles of inorganic MS, respectively; this historical synopsis is particularly interesting and informative. The discussion of spark source MS includes an excellent and up-to-date treatment of the physics and dynamics of the spark discharge phenomenon as well as a thorough review of the technique's features.

Adams, F.; Gijbels, R.; Van Grieken, R. (eds.)

1988-01-01

290

Biomedical accelerator mass spectrometry  

NASA Astrophysics Data System (ADS)

Ultrasensitive SIMS with accelerator based spectrometers has recently begun to be applied to biomedical problems. Certain very long-lived radioisotopes of very low natural abundances can be used to trace metabolism at environmental dose levels ( [greater-or-equal, slanted] z mol in mg samples). 14C in particular can be employed to label a myriad of compounds. Competing technologies typically require super environmental doses that can perturb the system under investigation, followed by uncertain extrapolation to the low dose regime. 41Ca and 26Al are also used as elemental tracers. Given the sensitivity of the accelerator method, care must be taken to avoid contamination of the mass spectrometer and the apparatus employed in prior sample handling including chemical separation. This infant field comprises the efforts of a dozen accelerator laboratories. The Center for Accelerator Mass Spectrometry has been particularly active. In addition to collaborating with groups further afield, we are researching the kinematics and binding of genotoxins in-house, and we support innovative uses of our capability in the disciplines of chemistry, pharmacology, nutrition and physiology within the University of California. The field can be expected to grow further given the numerous potential applications and the efforts of several groups and companies to integrate more the accelerator technology into biomedical research programs; the development of miniaturized accelerator systems and ion sources capable of interfacing to conventional HPLC and GMC, etc. apparatus for complementary chemical analysis is anticipated for biomedical laboratories.

Freeman, Stewart P. H. T.; Vogel, John S.

1995-05-01

291

Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.  

PubMed

Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material. PMID:17654466

Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

2007-01-01

292

[Screening method for 29 forbidden or limited synthetic pigments in cheese by liquid chromatography/quadrupole time-of-flight mass spectrometry].  

PubMed

A screening method for 29 forbidden or limited synthetic pigments in cheese samples was established by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF MS). The pigments were extracted by n-hexane/water (3:1, v/v). After extraction, the n-hexane extract, water extract and residue, were obtained. The n-hexane extract was then cleaned-up by gel permeation chromatography (GPC). The water extract was extracted by acetonitrile, and the residue by ammonia water/methanol (1:99, v/v). The results showed that the 29 synthetic pigments with a wide range of polarities were extracted effectively with the recoveries between 70% and 95%, and matched well by Q-TOF MS precision mass searching to the mass spectral library with matching scores between 59. 66 and 99. 47. The quantitative analysis of the 29 pigments was carried out by Target MS/MS. The limits of detection (LODs) for 8 Sudan dyes were 0.4-2.5 micro/kg while for 21 water-soluble synthetic pigments were 20-80 microg/kg. The screening method is suitable for a wide range of synthetic pigments, and can be applied to food samples with proteins and fat in matrix. PMID:22097789

Zhao, Yansheng; Yang, Minli; Zhang, Feng; Feng, Feng; Chu, Xiaogang; Dong, Ying

2011-07-01

293

Rapid determination of pesticide residues in fruits and vegetables, using ultra-high-performance liquid chromatography/time-of-flight mass spectrometry.  

PubMed

A multiresidue method, based on the sample preparation by solid-phase extraction cartridges and detection by ultra-high-performance liquid chromatography/time-of-flight mass spectrometry (UHPLC/TOF-MS), was used for the analysis of 60 pesticides in vegetable and fruit samples. Quantitation by UHPLC/TOF-MS is accomplished by measuring the accurate mass of the protonated molecules [M+H](+). The mass accuracy typically obtained is routinely better than 2ppm. The rates of recovery for pesticides studied were satisfactory, ranging from 74% to 111% with a relative standard deviation (RSD) of less than 13.2%, at concentrations below 10?gkg(-1). The method limit of quantification (MLOQ) for most compounds was below the MRLs established by the Food Safety Standard Authority of India and the European Union. The uncertainty was determined using repeatability, recovery and calibration curves data for each pesticide. The method illustrated is suitable for routine quantitative analyses of pesticides in food samples. PMID:25172721

Sivaperumal, P; Anand, P; Riddhi, L

2015-02-01

294

Detection and quantification of neurotensin in human brain tissue by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.  

PubMed

A method was developed for mass spectrometric detection of neurotensin (NT)-like immunoreactivity and quantification of NT in human brain tissue. The method is based on immunoprecipitation followed by analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The identity of the major component of the immunoprecipitates as neurotensin was confirmed by fragment ion analysis on an electrospray ionization quadrupole time-of-flight instrument. MALDI-TOF-MS quantification of NT was achieved using stable-isotope-labeled NT as the internal standard, yielding an error of less than 5%. The method allowed detection of low-femtomole amounts of NT, staring from low-milligram amounts of lyophilized brain tissue. In addition to NT, several other peptides were detected in the purified samples, most of which, according to their molecular masses, corresponded to fragments of NT. The method is demonstrated with quantification of NT from human hypothalamus tissue, and a comparison is made with results obtained from competitive radioimmunoassay. PMID:10939406

Gobom, J; Kraeuter, K O; Persson, R; Steen, H; Roepstorff, P; Ekman, R

2000-07-15

295

Arsenic-containing fatty acids and hydrocarbons in marine oils - determination using reversed-phase HPLC-ICP-MS and HPLC-qTOF-MS.  

PubMed

Arsenolipids are the major arsenic species present in marine oils. Several structures of arsenolipids have been elucidated the last 5 years, demonstrating the chemical complexity of this trace element in the marine environment. Several commercial fish oils and marine oils, ranging in total arsenic concentrations from 1.6 to 12.5 mg kg(-1) oil, were analyzed for arsenolipids using reversed-phase high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The arsenolipids were quantified using three different arsenic-containing calibration standards; dimethylarsinate (DMA), triphenylarsinoxide (Ph?AsO) and a synthesized arsenic-containing hydrocarbon (AsHC) (dimethylarsinoyl nonadecane; C??H??AsO). The observed variation in signal intensity for arsenic during the gradient elution profile in reversed-phase HPLC was compensated for by determining the time-resolved response factors for the arsenolipids. Isotopes of germanium ((74)Ge) and indium ((115)In) were suited as internal standards for arsenic, and were used for verification of the arsenic signal response factors during the gradient elution. Dimethylarsinate was the most suitable calibration standard for the quantification of arsenolipids, with recoveries between 91% and 104% compared to total arsenic measurements in the same extracts. A range of marine oils was investigated, including oils of several fish species, cod liver and seal, as well as three commercial fish oils. The AsHCs - C??H??AsO, C??H??AsO and C??H??AsO - were identified as the major arsenolipids in the extracts of all oils by HPLC coupled with quadrupole time-of-flight mass spectrometry (qTOF-MS). Minor amounts of two arsenic-containing fatty acids (AsFAs) (C??H??AsO? and C??H??AsO?) were also detected in the oils. The sum of the AsHCs and the AsFAs determined in the present study accounted for 17-42% of the total arsenic in the oils. PMID:24607114

Sele, Veronika; Sloth, Jens J; Holmelid, Bjarte; Valdersnes, Stig; Skov, Kasper; Amlund, Heidi

2014-04-01

296

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

2013-11-01

297

A fast method for the determination of the PC/LPC ratio in intact serum by MALDI-TOF MS: an easy-to-follow lipid biomarker of inflammation.  

PubMed

The PC/LPC ratio of blood serum is increasingly considered to represent an important clinical parameter that reflects various kinds of diseases. Here, a simple and fast method of lipid analyses of "intact" blood serum (i.e. without extraction) by MALDI-TOF mass spectrometry is described. The novel procedure allows the accurate determination of the PC/LPC ratio, utilizing only a tiny amount of blood. The serum is diluted with distilled water and directly applied onto the MALDI target and, after drying, covered by a thin layer of the matrix solution (either 9-aminoacridine or 2,5-dihydroxybenzoic acid). Positive ion mass spectra acquired by using this procedure give similar peak patterns as the spectra of the lipid extracts of horse blood serum. Blood serum from fourteen different horses was used to set up and validate the new method of lipid analysis. The PC/LPC ratios determined with the fast "intact" method were compared with those obtained with classical MALDI-TOF MS and (31)P NMR analyses of the corresponding lipid extracts. As comparable data were obtained, this is a clear indication that extraction is not an absolute necessity. PMID:25016154

Angelini, Roberto; Vortmeier, Gerrit; Corcelli, Angela; Fuchs, Beate

2014-10-01

298

Challenges for Biomarker Discovery in Body Fluids Using SELDI-TOF-MS  

PubMed Central

Protein profiling using SELDI-TOF-MS has gained over the past few years an increasing interest in the field of biomarker discovery. The technology presents great potential if some parameters, such as sample handling, SELDI settings, and data analysis, are strictly controlled. Practical considerations to set up a robust and sensitive strategy for biomarker discovery are presented. This paper also reviews biological fluids generally available including a description of their peculiar properties and the preanalytical challenges inherent to sample collection and storage. Finally, some new insights for biomarker identification and validation challenges are provided. PMID:20029632

De Bock, Muriel; de Seny, Dominique; Meuwis, Marie-Alice; Chapelle, Jean-Paul; Louis, Edouard; Malaise, Michel; Merville, Marie-Paule; Fillet, Marianne

2010-01-01

299

Rapid Identification and Subtyping of Helicobacter cinaedi Strains by Intact-Cell Mass Spectrometry Profiling with the Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry  

PubMed Central

Helicobacter cinaedi infection is recognized as an increasingly important emerging disease in humans. Although H. cinaedi-like strains have been isolated from a variety of animals, it is difficult to identify particular isolates due to their unusual phenotypic profiles and the limited number of biochemical tests for detecting helicobacters. Moreover, analyses of the 16S rRNA gene sequences are also limited due to the high levels of similarity among closely related helicobacters. This study was conducted to evaluate intact-cell mass spectrometry (ICMS) profiling using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) as a tool for the identification of H. cinaedi. A total of 68 strains of H. cinaedi isolated from humans, dogs, a cat, and hamsters were examined in addition to other Helicobacter species. The major ICMS profiles of H. cinaedi were identical and differed from those of Helicobacter bilis, which show >98% sequence similarity at the 16S rRNA sequence level. A phyloproteomic analysis of the H. cinaedi strains examined in this work revealed that human isolates formed a single cluster that was distinct from that of the animal isolates, with the exception of two strains from dogs. These phyloproteomic results agreed with those of the phylogenetic analysis based on the nucleotide sequences of the hsp60 gene. Because they formed a distinct cluster in both analyses, our data suggest that animal strains may not be a major source of infection in humans. In conclusion, the ICMS profiles obtained using a MALDI-TOF MS approach may be useful for the identification and subtyping of H. cinaedi. PMID:24153128

Taniguchi, Takako; Sekiya, Ayumi; Higa, Mariko; Saeki, Yuji; Umeki, Kazumi; Okayama, Akihiko; Hayashi, Tetsuya

2014-01-01

300

Accelerator mass spectrometry.  

PubMed

In this overview the technique of accelerator mass spectrometry (AMS) and its use are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10(-12) and 10(-16)) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (mg and even sub-mg size) and shorter measuring times (less than 1 hr). The equipment used for AMS is almost exclusively based on the electrostatic tandem accelerator, although some of the newest systems are based on a slightly different principle. Dedicated accelerators as well as older "nuclear physics machines" can be found in the 80 or so AMS laboratories in existence today. The most widely used isotope studied with AMS is 14C. Besides radiocarbon dating this isotope is used in climate studies, biomedicine applications and many other fields. More than 100,000 14C samples are measured per year. Other isotopes studied include 10Be, 26Al, 36Cl, 41Ca, 59Ni, 129I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be less than 10% of the number of 14C samples. PMID:18470926

Hellborg, Ragnar; Skog, Göran

2008-01-01

301

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

2011-04-15

302

Global characterization of the photosynthetic glycerolipids from a marine diatom Stephanodiscus sp. by ultra performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight mass spectrometry.  

PubMed

The photosynthetic glycerolipids composition of algae is crucial for structural and physiological aspects. In this work, a comprehensive characterization of the photosynthetic glycerolipids of the diatom Stephanodiscus sp. was carried out by ultra performance liquid chromatography-electrospray ionization-quadrupole-time of flight mass spectrometry (UPLC-ESI-Q-TOF MS). By use of the MS(E) data collection mode, the Q-TOF instrument offered a very viable alternative to triple quadrupoles for precursor ion scanning of photosynthetic glycerolipids and had the advantage of high efficiency, selectivity, sensitivity and mass accuracy. Characteristic fragment ions were utilized to identify the structures and acyl compositions of photosynthetic glycerolipids. Comparing the abundance of fragment ions, it was possible to determine the position of the sn-glycerol-bound fatty acyl chains. As a result, four classes of photosynthetic glycerolipid in the extract of Stephanodiscus sp. were unambiguously identified, including 16 monogalactosyldiacylglycerols (MGDGs), 9 digalactosyldiacylglycerols (DGDGs), 23 sulfoquinovosyldiacylglycerols (SQDGs) and 8 phosphatidylglycerols (PGs). As far as our knowledge, this is the first report on global identification of photosynthetic glycerolipids, including lipid classes, fatty acyl composition within lipids and the location of fatty acids in lipids (sn-1 vs. sn-2), in the extract of marine microalgae by UPLC-ESI-Q-TOF MS directly. PMID:20172098

Xu, Jilin; Chen, Deying; Yan, Xiaojun; Chen, Juanjuan; Zhou, Chengxu

2010-03-17

303

Quantitative analysis of multiple urinary biomarkers of carcinoid tumors through gold-nanoparticle-assisted laser desorption/ionization time-of-flight mass spectrometry.  

PubMed

A simple technique for quantitative analysis of four urinary biomarkers, tryptophan (TRP), 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) of carcinoid tumors is developed using gold nanoparticles as the assisted matrix in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). The optimal SALDI conditions for the efficient ionization of those biomarkers are systematically explored by the adjustments of the concentrations of gold nanoparticles and internal standards. The mass spectra with strong signals and minimal background noise are obtained using 1-naphthaleneacetamide (NAD) as the internal standard. The calibration curves of the biomarker concentrations are determined using SALDI-TOF MS and the high linearity is obtained in all samples. For future clinical testing, multiplexed detection of those biomarkers in the urine samples of healthy males is performed. The successful quantitative detections of TRP, 5-HTP, 5-HT and 5-HIAA indicate that our technique provided great potentials to be developed a simple and rapid platform for the tumor biomarker detections. PMID:21704761

Kuo, Tsung-Rong; Chen, Jinn-Shiun; Chiu, Yu-Chen; Tsai, Chia-Yi; Hu, Cho-Chun; Chen, Chia-Chun

2011-08-01

304

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

2012-06-18

305

Simultaneous separation, identification and activity evaluation of three butyrylcholinesterase inhibitors from Plumula nelumbinis using on-line HPLC-UV coupled with ESI-IT-TOF-MS and BChE biochemical detection.  

PubMed

We have firstly established a method of high-performance liquid chromatography-ultraviolet analysis coupled with electrospray ionization-ion trap-time-of-flight mass spectrometry and butyrylcholinesterase biochemical detection (HPLC-UV-ESI-IT-TOF-MS-BChEBCD). Applying this on-line method to the identification of BChE inhibitors in a Plumula nelumbinis sample, three alkaloids, namely liensinine, isoliensinine, and neferine, have been detected as having a strong BChE inhibition activity for the first time; in addition, norisoliensinine and 6-hydroxynorisoliensinine were proposed as two new compounds identified by their UV and MS data. The HPLC fingerprint, the MS fragments of the components, and the BChE activity profile could be simultaneously recorded during real-time analysis of complex samples using this on-line approach. Tacrine, a BChE inhibitor, was used as a positive reference compound, and its detection limit in the biochemical detection system was 1 nmol. The BChE activity of 1g of P. nelumbinis sample was equal to that of 127.88 ?mol tacrine. The proposed on-line method has been validated as having good precision and reproducibility, and could be used to rapidly identify BChE inhibitors and to screen potential drugs for the treatment of Alzheimer's disease in complicated samples. PMID:23618192

Lin, Zongtao; Wang, Hong; Fu, Qingrong; An, Haijuan; Liang, Yi; Zhang, Baobao; Hashi, Yuki; Chen, Shizhong

2013-06-15

306

Identification of prohibitin 1 as a potential prognostic biomarker in human pancreatic carcinoma using modified aqueous two-phase partition system combined with 2D-MALDI-TOF-TOF-MS/MS.  

PubMed

Membrane proteins are an important source of potential targets for anticancer drugs or biomarkers for early diagnosis. In this study, we used a modified aqueous two-phase partition system combined with two-dimensional (2D) matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry (MS, 2D-MALDI-TOF-TOF-MS/MS) analysis to isolate and identify membrane proteins in PANC-1 pancreatic cancer cells. Using this method, we identified 55 proteins, of which 31 (56.4 %) were membrane proteins, which, according to gene ontology annotation, are associated with various cellular processes including cell signal transduction, differentiation, and apoptosis. Immunohistochemical analysis showed that the expression level of one of the identified mitochondria membrane proteins, prohibitin 1 (PHB1), is correlated with pancreatic carcinoma differentiation; PHB1 is expressed at a higher level in normal pancreatic tissue than in well-differentiated carcinoma tissue. Further studies showed that PHB1 plays a proapoptotic role in human pancreatic cancer cells, which suggests that PHB1 has antitumorigenic properties. In conclusion, we have provided a modified method for isolating and identifying membrane proteins and demonstrated that PHB1 may be a promising biomarker for early diagnosis and therapy of pancreatic (and potentially other) cancers. PMID:25344214

Zhong, Ning; Cui, Yazhou; Zhou, Xiaoyan; Li, Tianliang; Han, Jinxiang

2014-10-25

307

Linear electric field mass spectrometry  

DOEpatents

A mass spectrometer and methods for mass spectrometry are described. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field. 8 figs.

McComas, D.J.; Nordholt, J.E.

1992-12-01

308

Misidentification of Aspergillus nomius and Aspergillus tamarii as Aspergillus flavus: Characterization by Internal Transcribed Spacer, ?-Tubulin, and Calmodulin Gene Sequencing, Metabolic Fingerprinting, and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry  

PubMed Central

Aspergillus nomius and Aspergillus tamarii are Aspergillus species that phenotypically resemble Aspergillus flavus. In the last decade, a number of case reports have identified A. nomius and A. tamarii as causes of human infections. In this study, using an internal transcribed spacer, ?-tubulin, and calmodulin gene sequencing, only 8 of 11 clinical isolates reported as A. flavus in our clinical microbiology laboratory by phenotypic methods were identified as A. flavus. The other three isolates were A. nomius (n = 2) or A. tamarii (n = 1). The results corresponded with those of metabolic fingerprinting, in which the A. flavus, A. nomius, and A. tamarii strains were separated into three clusters based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC MS) analysis. The first two patients with A. nomius infections had invasive aspergillosis and chronic cavitary and fibrosing pulmonary and pleural aspergillosis, respectively, whereas the third patient had A. tamarii colonization of the airway. Identification of the 11 clinical isolates and three reference strains by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) showed that only six of the nine strains of A. flavus were identified correctly. None of the strains of A. nomius and A. tamarii was correctly identified. ?-Tubulin or the calmodulin gene should be the gene target of choice for identifying A. flavus, A. nomius, and A. tamarii. To improve the usefulness of MALDI-TOF MS, the number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability. PMID:24452174

Tam, Emily W. T.; Chen, Jonathan H. K.; Lau, Eunice C. L.; Ngan, Antonio H. Y.; Fung, Kitty S. C.; Lee, Kim-Chung; Lam, Ching-Wan; Yuen, Kwok-Yung

2014-01-01

309

Antioxidant and metabolite profiling of North American and neotropical blueberries using LC-TOF-MS and multivariate analyses.  

PubMed

There are many neotropical blueberries, and recent studies have shown that some have even stronger antioxidant activity than the well-known edible North American blueberries. Antioxidant marker compounds were predicted by applying multivariate statistics to data from LC-TOF-MS analysis and antioxidant assays of 3 North American blueberry species (Vaccinium corymbosum, Vaccinium angustifolium, and a defined mixture of Vaccinium virgatum with V. corymbosum) and 12 neotropical blueberry species (Anthopterus wardii, Cavendishia grandifolia, Cavendishia isernii, Ceratostema silvicola, Disterigma rimbachii, Macleania coccoloboides, Macleania cordifolia, Macleania rupestris, Satyria boliviana, Sphyrospermum buxifolium, Sphyrospermum cordifolium, and Sphyrospermum ellipticum). Fourteen antioxidant markers were detected, and 12 of these, including 7 anthocyanins, 3 flavonols, 1 hydroxycinnamic acid, and 1 iridoid glycoside, were identified. This application of multivariate analysis to bioactivity and mass data can be used for identification of pharmacologically active natural products and may help to determine which neotropical blueberry species will be prioritized for agricultural development. Also, the compositional differences between North American and neotropical blueberries were determined by chemometric analysis, and 44 marker compounds including 16 anthocyanins, 15 flavonoids, 7 hydroxycinnamic acid derivatives, 5 triterpene glycosides, and 1 iridoid glycoside were identified. PMID:23547798

Ma, Chunhui; Dastmalchi, Keyvan; Flores, Gema; Wu, Shi-Biao; Pedraza-Peñalosa, Paola; Long, Chunlin; Kennelly, Edward J

2013-04-10

310

Mass spectrometry. [in organic chemistry  

NASA Technical Reports Server (NTRS)

A review of mass spectrometry in organic chemistry is given, dealing with advances in instrumentation and computer techniques, selected topics in gas-phase ion chemistry, and applications in such fields as biomedicine, natural-product studies, and environmental pollution analysis. Innovative techniques and instrumentation are discussed, along with chromatographic-mass spectrometric on-line computer techniques, mass spectral interpretation and management techniques, and such topics in gas-phase ion chemistry as electron-impact ionization and decomposition, photoionization, field ionization and desorption, high-pressure mass spectrometry, ion cyclotron resonance, and isomerization reactions of organic ions. Applications of mass spectrometry are examined with respect to bio-oligomers and their constituents, biomedically important substances, microbiology, environmental organic analysis, and organic geochemistry.

Burlingame, A. L.; Shackleton, C. H. L.; Howe, I.; Chizhov, O. S.

1978-01-01

311

Application of Whole-Cell Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Rapid Identification and Clustering Analysis of Pantoea Species ? †  

PubMed Central

Pantoea agglomerans is an ecologically diverse taxon that includes commercially important plant-beneficial strains and opportunistic clinical isolates. Standard biochemical identification methods in diagnostic laboratories were repeatedly shown to run into false-positive identifications of P. agglomerans, a fact which is also reflected by the high number of 16S rRNA gene sequences in public databases that are incorrectly assigned to this species. More reliable methods for rapid identification are required to ascertain the prevalence of this species in clinical samples and to evaluate the biosafety of beneficial isolates. Whole-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) methods and reference spectra (SuperSpectrum) were developed for accurate identification of P. agglomerans and related bacteria and used to detect differences in the protein profile within variants of the same strain, including a ribosomal point mutation conferring streptomycin resistance. MALDI-TOF MS-based clustering was shown to generally agree with classification based on gyrB sequencing, allowing rapid and reliable identification at the species level. PMID:20453125

Rezzonico, Fabio; Vogel, Guido; Duffy, Brion; Tonolla, Mauro

2010-01-01

312

[Determination of ten basic dyes in meat products by ultra fast liquid chromatography-ion trap time of flight mass spectrometry].  

PubMed

A method was developed for the simultaneous determination of 10 basic dyes in meat products using ultra fast liquid chromatography-ion trap time of flight mass spectrometry (LC-IT-TOF-MS). The target analytes were separated at a flow rate of 0.2 mL/min on a Waters Acquity UPLC BEH C18 (100 mm x 2.1 mm, 1.7 microm) column with a gradient elution. The mobile phase was 5 mmol/L ammonium acetate-acetonitrile (containing 0.1% (v/v) formic acid). The identification and quantification were achieved in positive ion mode with electro spray ionization source. The samples were extracted with a simple procedure using acetonitrile and cleaned up by weak cation exchange (Oasis WCX) solid phase extraction column. Ten basic dyes were determined by LC-IT-TOF-MS, and quantified by external standard method. The developed method showed a good linearity over the wide range of 1.0 - 100.0 microg/L, and the relative standard deviations (n = 7) were less than 8.54%. The average recoveries of the ten basic dyes at three levels (2, 10 and 25 microg/kg) were ranged from 65.39% to 119.18%. Therefore, this method, owing to its simplicity, rapidity and high sensitivity, has a good applicability to the simultaneous determination of dye residues in meat products. PMID:23256378

Zhang, Donglei; Wang, Lina; Chen, Xiaozhen; Wang, Jin; Cao, Hui; Huang, Liying

2012-08-01

313

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

PubMed

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. The extreme sensitivity of alkenyl-linked PL against acid treatment was used to estimate the plasmalogen content of spermatozoa. Compared with humans, boar spermatozoa are characterized by a lower variability of their PL and fatty acid composition. Additionally, boar spermatozoa contain much higher moieties of alkyl-linked compounds, e.g. 1-palmityl-2-docosapentaenoyl-sn-glycero-3-phosphocholine and 1-palmityl-2-docosahexaenoyl-sn-glycero-3-phosphocholine as well as the corresponding phosphatidylethanolamine (PE), while human spermatozoa are characterized by high contents of diacyl-PL, e.g. 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine. A considerable plasmalogen moiety, for instance 1-palmitenyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine is a typical feature of both, human and boar spermatozoa. It will be shown that these differences in PL composition can be very rapidly and conveniently assessed by MALDI-TOF MS in combination with TLC and also by 31P NMR. PMID:14990223

Lessig, Jacqueline; Gey, Claudia; Süss, Rosemarie; Schiller, Jürgen; Glander, Hans-Jürgen; Arnhold, Jürgen

2004-02-01

314

Identification of estrogen receptor proteins in breast cancer cells using matrix-assisted laser desorption/ionization time of flight mass spectrometry (Review)  

PubMed Central

Estrogen receptors [ERs (subtypes ? and ?)], classified as a nuclear receptor super family, are intracellular proteins with an important biological role as the transcription factors for estrogen target genes. For ER-induced transcription, an interaction must exist between ligand and coregulators. Coregulators may stimulate (coactivators) or inhibit (corepressors) transcription, following binding with a specific region of the gene, called the estrogen response element. Misbalanced activity of coregulators or higher ligand concentrations may cause increased cell proliferation, resulting in specific types of cancer. These are exhibited as overexpression of ER proteins. Breast cancer currently ranks first in the incidence and second in the mortality of cancer in females worldwide. In addition, 70% of breast tumors are ER? positive and the importance of these proteins for diagnostic use is indisputable. Early diagnosis of the tumor and its classification has a large influence on the selection of appropriate therapy, as ER-positive tumors demonstrate a positive response to hormonal therapy. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS) has been hypothesized to have great potential, as it offers reliable, robust and efficient analysis methods for biomarker monitoring and identification. The present review discusses ER protein analysis by MALDI TOF MS, including the crucial step of protein separation. PMID:24765135

HEGER, ZBYNEK; RODRIGO, MIGUEL ANGEL MERLOS; KRIZKOVA, SONA; ZITKA, ONDREJ; BEKLOVA, MIROSLAVA; KIZEK, RENE; ADAM, VOJTECH

2014-01-01

315

MALDI-TOF Mass Spectrometry Is a Fast and Reliable Platform for Identification and Ecological Studies of Species from Family Rhizobiaceae  

PubMed Central

Family Rhizobiaceae includes fast growing bacteria currently arranged into three genera, Rhizobium, Ensifer and Shinella, that contain pathogenic, symbiotic and saprophytic species. The identification of these species is not possible on the basis of physiological or biochemical traits and should be based on sequencing of several genes. Therefore alternative methods are necessary for rapid and reliable identification of members from family Rhizobiaceae. In this work we evaluated the suitability of Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for this purpose. Firstly, we evaluated the capability of this methodology to differentiate among species of family Rhizobiaceae including those closely related and then we extended the database of MALDI Biotyper 2.0 including the type strains of 56 species from genera Rhizobium, Ensifer and Shinella. Secondly, we evaluated the identification potential of this methodology by using several strains isolated from different sources previously identified on the basis of their rrs, recA and atpD gene sequences. The 100% of these strains were correctly identified showing that MALDI-TOF MS is an excellent tool for identification of fast growing rhizobia applicable to large populations of isolates in ecological and taxonomic studies. PMID:21655291

Ferreira, Laura; Sánchez-Juanes, Fernando; García-Fraile, Paula; Rivas, Raúl; Mateos, Pedro F.; Martínez-Molina, Eustoquio; González-Buitrago, José Manuel; Velázquez, Encarna

2011-01-01

316

Integrative normalization and comparative analysis for metabolic fingerprinting by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.  

PubMed

Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-TOF-MS) was applied to the comparative metabolic fingerprinting of a wild-type versus a double mutant strain of Escherichia coli lacking the transhydrogenases UdhA and PntAB. Using peak lists generated with the Leco ChromaTOF software as input, we developed retention time correction and data alignment tools (INCA). The accuracy of peak alignment and detection of 1.1- to 4-fold changes in metabolite concentration was validated by a spike-in experiment with 20 standard compounds. A list of 48 significant features that differentiated the two E. coli strains was obtained with an estimated false discovery rate (FDR) of <0.05. A total of 27 metabolites, mainly from the citrate cycle, were identified. That the signal intensity of the m/z 73 trace of the trimethylsilyl (TMS) group reflected true differences in metabolite abundance was confirmed by quantification of pyruvate, fumarate, malate, succinate, alpha-ketoglutarate, citrate, cis-aconitate, myo-inositol, and glucose-6-phosphate using compound specific fragment ions and stable isotope labeled standards. Relative standard deviations for metabolite extraction and GC x GC-TOF-MS analysis of those analytes ranged from 13.2 to 26.3% for the universal m/z 73 trace and 7.4 to 24.5% for the analyte specific fragment ion trace. PMID:19522528

Almstetter, Martin F; Appel, Inka J; Gruber, Michael A; Lottaz, Claudio; Timischl, Birgit; Spang, Rainer; Dettmer, Katja; Oefner, Peter J

2009-07-15

317

Identification of the Corn Pathogen Pantoea stewartii by Mass Spectrometry of Whole-Cell Extracts and Its Detection with Novel PCR Primers ?  

PubMed Central

Pantoea stewartii subsp. stewartii is the causative agent of Stewart's wilt, a bacterial disease transmitted by the corn flea beetle mainly to sweet corn (Zea mays). In many countries, it is classified as a quarantine organism and must be differentiated from other yellow enteric bacteria frequently occurring with corn. We have created novel primers from the pstS-glmS region of P. stewartii for use in conventional PCR (cPCR) and quantitative PCR (qPCR). To facilitate rapid diagnosis, we applied matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Using whole-cell protein extracts, profiles were generated with a Bruker microflex machine, and the bacteria classified. P. stewartii strains were clearly distinguished from strains of Pantoea agglomerans, Pantoea dispersa, and Pantoea ananatis. Dendrogram analysis of the protein profiles confirmed the score values and showed the formation of separate clades for each species. The identification achieved by MALDI-TOF MS analysis agrees with the diagnosis by specific PCR primers. The combination of both methods allows a rapid and simple identification of the corn pathogen. P. stewartii subsp. stewartii and P. stewartii subsp. indologenes are highly related and can be distinguished not only by virulence assays and indole tests but also by a characteristic pattern in the nucleotide sequence of recA. PMID:20656863

Wensing, Annette; Zimmermann, Stefan; Geider, Klaus

2010-01-01

318

Identification of the corn pathogen Pantoea stewartii by mass spectrometry of whole-cell extracts and its detection with novel PCR primers.  

PubMed

Pantoea stewartii subsp. stewartii is the causative agent of Stewart's wilt, a bacterial disease transmitted by the corn flea beetle mainly to sweet corn (Zea mays). In many countries, it is classified as a quarantine organism and must be differentiated from other yellow enteric bacteria frequently occurring with corn. We have created novel primers from the pstS-glmS region of P. stewartii for use in conventional PCR (cPCR) and quantitative PCR (qPCR). To facilitate rapid diagnosis, we applied matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Using whole-cell protein extracts, profiles were generated with a Bruker microflex machine, and the bacteria classified. P. stewartii strains were clearly distinguished from strains of Pantoea agglomerans, Pantoea dispersa, and Pantoea ananatis. Dendrogram analysis of the protein profiles confirmed the score values and showed the formation of separate clades for each species. The identification achieved by MALDI-TOF MS analysis agrees with the diagnosis by specific PCR primers. The combination of both methods allows a rapid and simple identification of the corn pathogen. P. stewartii subsp. stewartii and P. stewartii subsp. indologenes are highly related and can be distinguished not only by virulence assays and indole tests but also by a characteristic pattern in the nucleotide sequence of recA. PMID:20656863

Wensing, Annette; Zimmermann, Stefan; Geider, Klaus

2010-09-01

319

Identification and Comparison of the Polar Phospholipids in Normal and Dry Eye Rabbit Tears by MALDI-TOF Mass Spectrometry  

PubMed Central

Purpose To identify and compare the phosphorylated lipids in normal and dry eye rabbit tears using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Methods MALDI-TOF MS studies were performed on tear samples from normal and dry eyes of female New Zealand White rabbits. Experimental dry eye was induced by complete removal of the main and accessory lacrimal glands and nictitating membranes. A solid ionic crystal MALDI matrix of paranitroaniline and butyric acid was used to enhance the mass spectral responses of the phospholipids. In addition, a novel lipid isolation, preconcentration, and clean-up method using pipettes containing immobilized metal ion affinity chromatography (IMAC) medium was used. Results The polar phospholipids present in the normal and dry eye rabbit tears showed both similarities and differences. Species related to platelet-activating factor (PAF) and/or lysophosphatidylcholine (lyso-PC), phosphatidylcholine (PC), and sphingomyelin (SM) were found in both the normal and dry eye rabbit tears. However, the number of types and the concentrations of SM molecules were markedly greater in the dry eye tears than in the normal tears. In addition, phosphatidylserine (PS) species that were readily detectable in dry eye tears were not found in normal tears. Conclusions The combination of immobilized metal ion affinity chromatography and the solid ionic crystal matrix for MALDI enabled the detection and study of phosphorylated lipids in the tears. Specific differences between phospholipid levels in normal and dry eye tears were observable with this methodology. The appearance of various SM species only in the dry eye tears may provide markers for this disease state in the future. PMID:16877399

Ham, Bryan M.; Cole, Richard B.; Jacob, Jean T.

2008-01-01

320

Hyphenation of supercritical fluid chromatography and two-dimensional gas chromatography-mass spectrometry for group type separations.  

PubMed

The Fischer-Tropsch (FT) process produces a variety of compounds over a wide carbon number range and the synthetic crude oil produced by this process is rich in highly valuable olefins and oxygenates, which crude oil only contains at trace levels. The characterization of these products is very challenging even when using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOF-MS). The separation between cyclic paraffins and olefins is especially difficult since they elute in similar positions on the GC×GC chromatogram and since they have identical molecular masses with indistinguishable fragmentation patterns. Previously, a high performance liquid chromatography (HPLC) fractionation procedure was used prior to GC×GC-TOF-MS analysis to distinguish between alkenes and alkanes, both cyclic and non-cyclic, however, there was co-elution of the solvents used in the HPLC fractionation procedure, and the volatile components in the gasoline sample and the dilution introduced by the off-line fractionation procedure made it very difficult to investigate components present at very low concentrations. The hyphenation of supercritical fluid chromatography (SFC) to GC×GC is less complicated and the removal of the supercritical CO2 can be easily achieved without any loss of the volatile sample components, eliminating the introduction of co-eluting solvents as well as the dilution effect. This paper describes the on-line hyphenation of SFC to a GC×GC system in order to comprehensively characterize the chemical groups (saturates, unsaturates, oxygenates and aromatics) in an FT sample. PMID:23647609

Potgieter, H; van der Westhuizen, R; Rohwer, E; Malan, D

2013-06-14

321

Urea free and more efficient sample preparation method for mass spectrometry based protein identification via combining the formic acid-assisted chemical cleavage and trypsin digestion.  

PubMed

A formic acid (FA)-assisted sample preparation method was presented for protein identification via mass spectrometry (MS). Detailedly, an aqueous solution containing 2% FA and dithiothreitol was selected to perform protein denaturation, aspartic acid (D) sites cleavage and disulfide linkages reduction simultaneously at 108°C for 2h. Subsequently, FA wiped off via vacuum concentration. Finally, iodoacetamide (IAA) alkylation and trypsin digestion could be performed ordinally. A series of model proteins (BSA, ?-lactoglobulin and apo-Transferrin) were treated respectively using such method, followed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The identified peptide number was increased by ? 80% in comparison with the conventional urea-assisted sample preparation method. Moreover, BSA identification was achieved efficiently down to femtomole (25 ± 0 sequence coverage and 16 ± 1 peptides) via such method. In contrast, there were not peptides identified confidently via the urea-assisted method before desalination via the C18 zip tip. The absence of urea in this sample preparation method was an advantage for the more favorable digestion and MALDI-TOF MS analysis. The performances of two methods for the real sample (rat liver proteome) were also compared, followed by a nanoflow reversed-phase liquid chromatography with electrospray ionization tandem mass spectrometry system analysis. As a result, 1335 ± 43 peptides were identified confidently (false discovery rate <1%) via FA-assisted method, corresponding to 295 ± 12 proteins (of top match=1 and requiring 2 unique peptides at least). In contrast, there were only 1107 ± 16 peptides (corresponding to 231 ± 10 proteins) obtained from the conventional urea-assisted method. It was serving as a more efficient protein sample preparation method for researching specific proteomes better, and providing assistance to develop other proteomics analysis methods, such as, peptide quantitative analysis. PMID:22063562

Wu, Shuaibin; Yang, Kaiguang; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2011-10-30

322

Imaging mass spectrometry in microbiology  

PubMed Central

Mass spectrometry tools which allow for the 2-D visualization of the distribution of trace metals, metabolites, surface lipids, peptides and proteins directly from biological samples without the need for chemical tagging or antibodies are becoming increasingly useful for microbiology applications. These tools, comprised of different imaging mass spectrometry techniques, are ushering in an exciting new era of discovery by allowing for the generation of chemical hypotheses based on of the spatial mapping of atoms and molecules that can correlate to or transcend observed phenotypes. In this review, we explore the wide range of imaging mass spectrometry techniques available to microbiologists and describe their unique applications to microbiology with respect to the types of microbiology samples to be investigated. PMID:21822293

Watrous, Jeramie D.; Dorrestein, Pieter C.

2013-01-01

323

Characterization of unknown compounds from stainless steel plates in matrix-assisted laser desorption\\/ionization mass spectrometry  

Microsoft Academic Search

Peaks originating from unknown compounds on stainless steel plates used in matrix-assisted laser desorption\\/ionization (MALDI)\\u000a mass spectrometers are observed around m\\/z 304.3, 332.3, 360.4, and 388.4 regardless of the matrix and\\/or solvent, and are even observed with bare plates. These peaks\\u000a were characterized using three different types of MALDI-MS instrumentation: MALDI-TOF MS, MALDI-TOF\\/TOF MS, and MALDI-FTMS.\\u000a The fragmentation data from

Hyo-Jik Yang; Kyu Hwan Park; Hyun Sik Kim; Jeongkwon Kima

2010-01-01

324

SELDI-TOF MS Whole Serum Proteomic Profiling with IMAC Surface Does Not Reliably Detect Prostate Cancer  

PubMed Central

BACKGROUND The analysis of bodily fluids using SELDI-TOF MS has been reported to identify signatures of spectral peaks that can be used to differentiate patients with a specific disease from normal or control patients. This report is the 2nd of 2 companion articles describing a validation study of a SELDI-TOF MS approach with IMAC surface sample processing to identify prostatic adenocarcinoma. METHODS We sought to derive a decision algorithm for classification of prostate cancer from SELDI-TOF MS spectral data from a new retrospective sample cohort of 400 specimens. This new cohort was selected to minimize possible confounders identified in the previous study described in the companion paper. RESULTS The resulting new classifier failed to separate patients with prostate cancer from biopsy-negative controls; nor did it separate patients with prostate cancer with Gleason scores <7 from those with Gleason scores ?7. CONCLUSIONS In this, the 2nd stage of our planned validation process, the SELDI-TOF MS– based protein expression profiling approach did not perform well enough to advance to the 3rd (prospective study) stage. We conclude that the results from our previous studies—in which differentiation between prostate cancer and noncancer was demonstrated—are not generalizable. Earlier study samples likely had biases in sample selection that upon removal, as in the present study, resulted in inability of the technique to discriminate cancer from non-cancer cases. PMID:18024530

McLerran, Dale; Grizzle, William E.; Feng, Ziding; Thompson, Ian M.; Bigbee, William L.; Cazares, Lisa H.; Chan, Daniel W.; Dahlgren, Jackie; Diaz, Jose; Kagan, Jacob; Lin, Daniel W.; Malik, Gunjan; Oelschlager, Denise; Partin, Alan; Randolph, Timothy W.; Sokoll, Lori; Srivastava, Shiv; Srivastava, Sudhir; Thornquist, Mark; Troyer, Dean; Wright, George L.; Zhang, Zhen; Zhu, Liu; Semmes, O. John

2015-01-01

325

Serum profiling by mass spectrometry combined with bioinformatics for the biomarkers discovery in diffuse large B-cell lymphoma.  

PubMed

The aim of this study was to identify potential serum biomarkers of diffuse large B-cell lymphoma (DLBCL) and to detect DLBCL therapy response biomarkers. DLBCL serum proteomic analysis was performed using the CM10 ProteinChip mass spectrometry (SELDI-TOF-MS) approach combined with bioinformatics. A total of 178 samples were analyzed in this study from untreated early stage DLBCL patients (38), patients with inflammatory lymphadenopathy (13), healthy donors (35), post-treatment non-relapsed DLBCL patients (53), and relapsed DLBCL patients (39). Model 1 formed by nine protein peaks (m/z: 6443, 5913, 6198, 4098, 7775, 9293, 5946, 5977, and 4628) could be used to distinguish DLBCL patients from healthy individuals with an accuracy of 95.89 % (70/73). The diagnostic pattern constructed using the support vector machine including the nine proteins of model 1, showed a maximum Youden's Index. Model 2 formed by three protein peaks (m/z: 3942, 6639, and 4121) could be used to distinguish DLBCL patients from those with inflammatory lymphadenopathy with an accuracy of 94.12 % (48/51). Model 3 formed by six protein peaks could distinguish patients with inflammatory lymphadenopathy from healthy individuals with an accuracy of 97.92 % (47/48). Model 4 could be used to distinguish non-relapsed DLBCL patients from relapsed DLBCL patients with an accuracy of 84.78 % (78/92). The four patterns were validated by leave-one-out cross-validation. These data demonstrate that the CM10 ProteinChip and SELDI-TOF-MS approach combined with bioinformatics can be used effectively to screen for the differential protein expression profiles of DLBCL patients and to predict the response to therapy. PMID:25409615

Xu, Wenhong; Hu, Yue; He, Xuexin; Li, Jun; Pan, Tao; Liu, Hai; Wu, Xianguo; He, Hong; Ge, Weiting; Yu, Jiekai; Wei, Qichun; Zheng, Shu; Zhang, Suzhan; Chen, Yiding

2014-11-20

326

MALDI-TOF mass spectrometry screening of cholelithiasis risk markers in the gene of HNF1alpha.  

PubMed

In recent years MALDI-TOF MS gained importance for high-throughput DNA analysis. In the present study this technique was used for the pathogenetic analysis of gallstone disease. The intestinal apical sodium-dependent bile acid transporter (ASBT) shows a genetic association with gallstone disease. ASBT has 3 binding sites in its 5'UTR for hepatocyte nuclear factor 1alpha (HNF1alpha). We hypothesized that genetic alterations in the HNF1alpha gene could influence ASBT expression. The gene HNF1alpha was sequenced in 46 Stuttgart random samples, composed of 16 controls and 30 gallstone patients. Subsequently, two independent cohorts (Stuttgart: 67 gallstones carriers, 109 controls, Leutkirch: 112 gallstone carriers, 99 controls) were screened by MALDI-TOF MS. The subjects were further divided by gender and weight. 24 known polymorphisms and two novel SNPs in the 3'UTR of HNF1alpha were detected (c.*220G>A and c.*1151G>A). After gender-specific sub-division of the pooled cohorts, 4 SNPs resulted in significant differences between male gallstone carriers and male controls (Stuttgart/Leutkirch: rs2255531 OR=2.78; p=0.006, rs1169288 OR=2.13; p=0.032, rs7310409 OR=2.34; p=0.025 and rs1169294 OR=2.13; p=0.031). Two novel variants in the 3'UTR of HNF1alpha were detected and four SNPs of HNF1alpha show a significant association to cholelithiasis in male gallstone patients. This article is part of a Special Section entitled: Understanding genome regulation and genetic diversity by mass spectrometry. PMID:22569176

Richter, Dominique; Harsch, Simone; Strohmeyer, André; Hirobe-Jahn, Satoko; Schimmel, Silke; Renner, Olga; Müller, Oliver; Schäffeler, Elke; Kratzer, Wolfgang; Schwab, Matthias; Stange, Eduard F

2012-06-27

327

Characterization of the organic contamination pattern of a hyper-saline ecosystem by rapid screening using gas chromatography coupled to high-resolution time-of-flight mass spectrometry.  

PubMed

In this paper, gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF MS) has been applied to evaluate organic pollution in a hyper-saline aquatic environment. Firstly, a target screening was made for a list of 150 GC-amenable organic micro-contaminants, including PAHs, octyl/nonyl phenols, PCBs, PBDEs, and a notable number of pesticides, such us insecticides (organochlorines, organophosphorus, carbamates and pyrethroids), herbicides (triazines and chloroacetanilides), fungicides and several transformation products. This methodology was applied to brine samples, with a salt content from 112 g/L to saturation, and to samples from Artemia populations (crustacean Anostraca) collected during 1 year from three sampling stations in saltworks bodies sited in the Ebro river delta. Around 50 target contaminants, belong to chemical families included in the list of priority substances within the framework on European water policy. Additionally, a non-target analysis was performed in both types of samples with the objective of investigating the presence of other non-selected organic compounds taking advantage of the potential of GC-TOF MS (high sensitivity in full-spectrum acquisition mode, accurate mass measurements) for searching unknowns. Organophosphorus pesticides were the contaminants more frequently detected in brine samples. Other compounds usually present in urban and industrial wastewaters, like caffeine, methylparaben, butylated-hydroxytoluene and N-butylbenzenesulfonamide were also detected in brines. The herbicide simazine and the insecticide chlorpyrifos were among the contaminants detected in Artemia samples. Results of this work reveal a potential threat to vulnerable populations inhabiting the hyper-saline ecosystem. The valuable contribution of GC-TOF MS in environmental analysis, allowing the rapid screening of a large number of organic contaminants, is also demonstrated in this paper. PMID:22789816

Serrano, Roque; Portolés, Tania; Blanes, Miguel A; Hernández, Félix; Navarro, Juan C; Varó, Inmaculada; Amat, Francisco

2012-09-01

328

Differentiation in MALDI-TOF MS and FTIR spectra between two closely related species Acidovorax oryzae and Acidovorax citrulli  

PubMed Central

Background Two important plant pathogenic bacteria Acidovorax oryzae and Acidovorax citrulli are closely related and often not easy to be differentiated from each other, which often resulted in a false identification between them based on traditional methods such as carbon source utilization profile, fatty acid methyl esters, and ELISA detection tests. MALDI-TOF MS and Fourier transform infrared (FTIR) spectra have recently been successfully applied in bacterial identification and classification, which provide an alternate method for differentiating the two species. Results Characterization and comparison of the 10 A. oryzae strains and 10 A. citrulli strains were performed based on traditional bacteriological methods, MALDI-TOF MS, and FTIR spectroscopy. Our results showed that the identity of the two closely related plant pathogenic bacteria A. oryzae and A. citrulli was able to be confirmed by both pathogenicity tests and species-specific PCR, but the two species were difficult to be differentiated based on Biolog and FAME profile as well as 16?S rRNA sequence analysis. However, there were significant differences in MALDI-TOF MS and FTIR spectra between the two species of Acidovorax. MALDI-TOF MS revealed that 22 and 18 peaks were specific to A. oryzae and A. citrulli, respectively, while FTIR spectra of the two species of Acidovorax have the specific peaks at 1738, 1311, 1128, 1078, 989?cm-1 and at 1337, 968, 933, 916, 786?cm-1, respectively. Conclusions This study indicated that MALDI-TOF MS and FTIR spectra may give a new strategy for rapid bacterial identification and differentiation of the two closely related species of Acidovorax. PMID:22900823

2012-01-01

329

Ion funnel trap interface for orthogonal time-of-flight mass spectrometry.  

PubMed

A combined electrodynamic ion funnel and ion trap coupled to an orthogonal acceleration (oa)-time-of-flight mass spectrometer was developed and characterized. The ion trap was incorporated through the use of added terminal electrodynamic ion funnel electrodes enabling control over the axial dc gradient in the trap section. The ion trap operates efficiently at a pressure of approximately 1 Torr, and measurements indicate a maximum charge capacity of approximately 3 x 10(7) charges. An order of magnitude increase in sensitivity was observed in the analysis of low concentration peptides mixtures with orthogonal acceleration (oa)-time-of-flight mass spectrometry (oa-TOF MS) in the trapping mode as compared to the continuous regime. A signal increase in the trapping mode was accompanied by reduction in the chemical background, due to more efficient desolvation of, for example, solvent related clusters. Controlling the ion trap ejection time was found to result in efficient removal of singly charged species and improving signal-to-noise ratio (S/N) for the multiply charged analytes. PMID:17850113

Ibrahim, Yehia; Belov, Mikhail E; Tolmachev, Aleksey V; Prior, David C; Smith, Richard D

2007-10-15

330

Size Characterization of Colloidal Platinum Nanoparticles by MALDI-TOF Mass Spectrometry  

SciTech Connect

In this work, matrix assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) has been utilized to characterize colloidal platinum nanoparticles synthesized in the 1-4 nm size range. The nanoparticles were prepared via a solution-based method in which the size could be controlled by varying reaction conditions, such as the alcohol used as the reductant. Poly(vinylpyrrolidone), or PVP, (MW = 29,000 g/mol) was employed as a capping agent to stabilize the synthesized nanoparticles in solution. A model for determining the size of the metallic nanoparticle core from MALDI-TOF mass spectra has been developed and verified through correlation with particle sizes from transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. In this model it was assumed that 1.85 nm nanoparticles are capped by one PVP chain, which was verified through experiments performed with capped and uncapped nanoparticles. Larger nanoparticles are capped by either two (2.60 and 2.94 nm) or three (3.69 nm) PVP chains. These findings clearly indicate the usefulness of MALDI-TOF MS as a technique for fully characterizing nanoscale materials in order to elucidate structure-property relationships.

Navin, Jason K.; Grass, Michael E.; Somorjai, Gabor A.; Marsh, Anderson L.

2009-08-15

331

Liquid chromatography/mass spectrometry characterization of Escherichia coli and Shigella species.  

PubMed

Liquid chromatography/quadrupole time of flight mass spectrometry (LC/QTOF MS) utilizing electrospray ionization was employed to monitor protein expression in Escherichia coli and Shigella organisms. Comparison with MALDI/TOF-MS revealed more proteins, particularly above 15 kDa. A combination of automated charge state deconvolution, spectral mirroring, and spectral subtraction was used to reveal subtle differences in the LC/MS data. Reproducible intact protein biomarker candidates were discovered based on their unique mass, retention time, and relative intensity. These marker candidates were implemented to differentiate closely related strain types, (e.g., two distinct isolates of E. coli O157:H7) and to correctly identify unknown pathogens. This LC/MS approach is less labor-intensive than pulsed-field gel electrophoresis, affords greater specificity than real-time PCR, and requires no primers or antibodies. Additionally, this approach would be beneficial during outbreaks of foodborne disease or bioterrorism investigations by complementing methods typically used in diagnostic microbiology laboratories. PMID:18692404

Everley, Robert A; Mott, Tiffany M; Wyatt, Shane A; Toney, Denise M; Croley, Timothy R

2008-11-01

332

Physical characterization of succinylated type I collagen by Raman spectra and MALDI-TOF/MS and in vitro evaluation for biomedical applications  

NASA Astrophysics Data System (ADS)

In this study, we report on physical and in vitro biological characterization of succinylated collagen (SC). SC was prepared by succinylation of type I bovine tendon collagen. SC swells and dissolves in physiological pH buffers (pH 7.4) Biocompatibility of SC to collagen for fibroblasts was comparable but L6 myoblasts showed pronounced proliferation and differentiation with SC. Using the MALDI-TOF/MS technique, SC was found with increased molecular mass by 16,359 Da per molecule which corresponds to about 54 succinyl groups covalently linked to the collagen strand. Raman spectroscopy revealed the retention of triple helical structure conformation in the presence of linked succinyl groups. New peaks near 1737, 1675 and 1420 cm -1 and decreased intensities near 2440 and 488 cm -1 provides the most convenient marker bands for succinylation of collagen. The intense band regions near 2856-2934, 2724, and 1445 cm -1 also confirms the existence of succinyl groups.

Kumar, Ramadhar; Sripriya, R.; Balaji, S.; Senthil Kumar, M.; Sehgal, P. K.

2011-05-01

333

Electrospray Ionization Mass Spectrometry  

SciTech Connect

Electrospray Ionization (ESI) is a process whereby gas phase ions are created from molecules in solution. As a solution exits a narrow tube in the presence of a strong electric field, an aerosol of charged droplets are is formed that produces gas phase ions as they it desolvates. ESI-MS comprises the creation of ions by ESI and the determination of their mass to charge ratio (m/z) by MS.

Kelly, Ryan T.; Marginean, Ioan; Tang, Keqi

2014-06-13

334

Population Studies of Intact Vitamin D Binding Protein by Affinity Capture ESI-TOF-MS  

PubMed Central

Blood plasma proteins with molecular weights greater than approximately 30 kDa are refractory to comprehensive, high-throughput qualitative characterization of microheterogeneity across human populations. Analytical techniques for obtaining high mass resolution for targeted, intact protein characterization and, separately, high sample throughput exist, but efficient means of coupling these assay characteristics remain rather limited. This article discusses the impetus for analyzing intact proteins in a targeted manner across populations and describes the methodology required to couple mass spectrometric immunoassay with electrospray ionization mass spectrometry for the purpose of qualitatively characterizing a prototypical large plasma protein, vitamin D binding protein, across populations. PMID:19137103

Borges, Chad R.; Jarvis, Jason W.; Oran, Paul E.; Rogers, Stephen P.; Nelson, Randall W.

2008-01-01

335

ENUMERATION OF CARBOHYDRATE HYDROXYL GROUPS BY SILYLATION AND MATRIX ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

A method for enumerating hydroxyl group in analytes is described and applied to various carbohydrates and polyols. The analytes were derivatized in solution by using trimethylsilylimidazole (TMSI) and the products were analyzed without chromatography in a MALDI-TOF-MS. The mass spectra revealed co...

336

Novel PDD-PDT system based on spectrophotometric real-time fluorescence monitoring and MALDI-TOF-MS analysis of tumors  

NASA Astrophysics Data System (ADS)

In the PDT practice for tumor patients, the dose and irradiation time for the treatment are chosen by experience and not by real need. To establish advanced PDD-PDT model system for patients, we developed a method for monitoring the cell-death based on a spectrophotometric real-time change in fluorescence in HeLa-tumors during Photofrin®-PDT and ALA-PDT. Here, we describe the results of application of the new PDD-PDT system to human tumors. The fluorescence spectra obtained from human tumors were analyzed by the differential spectral analysis. The mass-spectral changes of tumor tissues during PDD-PDT were also examined by MALDI-TOF-MS/MS. The first author's seborrheic keratosis was monitored with this system during the PDD-PDT with a topically applied ALA-ointment. The changes in fluorescence spectrum were successfully detected, and the tumor regressed completely within 5 months. The differential spectral analysis of PDD-PDT-fluorescence monitoring spectra of tumors and isolated mitochondria showed a marked decrease of three peaks in the red region indicative of the PDD (600 - 720 nm), and a transient rise followed by a decline of peaks in the green region indicative of the PDT (450 - 580 nm). The MALDI-TOF-MS analysis of PDD-PDT HeLa-tumors showed a consumption of Photofrin-deuteroporphyrin and ALA-PpIX, and decreases in protein mass in the range of 4,000 - 16,000 Da, m/z 4929, 8564, 10089, 15000, and an increase in m/z 7002 in a Photofrin® PDD-PDT monitoring tumor.

Yoshida, Takato O.; Kohno, Eiji; Dodeller, Marc; Sakurai, Takashi; Yamamoto, Seiji; Terakawa, Susumu

2009-06-01

337

Multidimensional gas chromatography in combination with accurate mass, tandem mass spectrometry, and element-specific detection for identification of sulfur compounds in tobacco smoke.  

PubMed

A method is developed for identification of sulfur compounds in tobacco smoke extract. The method is based on large volume injection (LVI) of 10?L of tobacco smoke extract followed by selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography (GC) coupled to a hybrid quadrupole time-of-flight mass spectrometer (Q-TOF-MS) using electron ionization (EI) and positive chemical ionization (PCI), with parallel sulfur chemiluminescence detection (SCD). In order to identify each individual sulfur compound, sequential heart-cuts of 28 sulfur fractions from (1)D GC to (2)D GC were performed with the three MS detection modes (SCD/EI-TOF-MS, SCD/PCI-TOF-MS, and SCD/PCI-Q-TOF-MS). Thirty sulfur compounds were positively identified by MS library search, linear retention indices (LRI), molecular mass determination using PCI accurate mass spectra, formula calculation using EI and PCI accurate mass spectra, and structure elucidation using collision activated dissociation (CAD) of the protonated molecule. Additionally, 11 molecular formulas were obtained for unknown sulfur compounds. The determined values of the identified and unknown sulfur compounds were in the range of 10-740ngmg total particulate matter (TPM) (RSD: 1.2-12%, n=3). PMID:25087743

Ochiai, Nobuo; Mitsui, Kazuhisa; Sasamoto, Kikuo; Yoshimura, Yuta; David, Frank; Sandra, Pat

2014-09-01

338

Advantages of Using Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry as a Rapid Diagnostic Tool for Identification of Yeasts and Mycobacteria in the Clinical Microbiological Laboratory  

PubMed Central

Yeast and mycobacteria can cause infections in immunocompromised patients and normal hosts. The rapid identification of these organisms can significantly improve patient care. There has been an increasing number of studies on using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for rapid yeast and mycobacterial identifications. However, studies on direct comparisons between the Bruker Biotyper and bioMérieux Vitek MS systems for the identification of yeast and mycobacteria have been limited. This study compared the performance of the two systems in their identification of 98 yeast and 102 mycobacteria isolates. Among the 98 yeast isolates, both systems generated species-level identifications in >70% of the specimens, of which Candida albicans was the most commonly cultured species. At a genus-level identification, the Biotyper system identified more isolates than the Vitek MS system for Candida (75/78 [96.2%]versus 68/78 [87.2%], respectively; P = 0.0426) and non-Candida yeasts (18/20 [90.0%]versus 7/20 [35.0%], respectively; P = 0.0008). For mycobacterial identification, the Biotyper system generated reliable identifications for 89 (87.3%) and 64 (62.8%) clinical isolates at the genus and species levels, respectively, from solid culture media, whereas the Vitek MS system did not generate any reliable identification. The MS method differentiated 12/21 clinical species, despite the fact that no differentiation between Mycobacterium abscessus and Mycobacterium chelonae was found by using 16S rRNA gene sequencing. In summary, the MALDI-TOF MS method provides short turnaround times and a standardized working protocol for the identification of yeast and mycobacteria. Our study demonstrates that MALDI-TOF MS is suitable as a first-line test for the identification of yeast and mycobacteria in clinical laboratories. PMID:24048537

Chen, Jonathan H. K.; Yam, Wing-Cheong; Ngan, Antonio H. Y.; Fung, Ami M. Y.; Woo, Wai-Lan; Yan, Mei-Kum; Choi, Garnet K. Y.; Ho, Pak-Leung; Cheng, Vincent C. C.

2013-01-01

339

Chemical profiling of triacylglycerols and diacylglycerols in cow milk fat by ultra-performance convergence chromatography combined with a quadrupole time-of-flight mass spectrometry.  

PubMed

An ultra-performance convergence chromatography (UPC(2)) system coupled with quadrupole time-of-flight mass spectrometry (Q-TOF-MS) was successfully utilised to analyse triacylglycerols and diacylglycerols in cow milk fat. This novel approach obtained an improved resolution of triacylglycerols in comparison to previously reported chromatographic methods combined with MS detector in a shorter analytical time. A total of 49 triacylglycerols and 7 diacylglycerols were identified according to their secondary MS profiles and elementary composition. Furthermore, UPC(2) is an environmental friendly analytical method with a drastic reduction of organic solvent usage. The established UPC(2)-MS approach has potential application in lipidomics as an alternative method besides LC-MS and GC-MS. PMID:24054231

Zhou, Qin; Gao, Boyan; Zhang, Xi; Xu, Yongwei; Shi, Haiming; Yu, Liangli Lucy

2014-01-15

340

Nanostructured Indium Tin Oxide Slides for Small-Molecule Profiling and Imaging Mass Spectrometry of Metabolites by Surface-Assisted Laser Desorption Ionization MS.  

PubMed

Due to their electrical conductivity and optical transparency, slides coated with a thin layer of indium tin oxide (ITO) are the standard substrate for protein imaging mass spectrometry on tissue samples by MALDI-TOF MS. We have now studied the rf magnetron sputtering deposition parameters to prepare ITO thin films on glass substrates with the required nanometric surface structure for their use in the matrix-free imaging of metabolites and small-molecule drugs, without affecting the transparency required for classical histology. The custom-made surfaces were characterized by atomic force microscopy, scanning electron microscopy, ellipsometry, UV, and laser desorption ionization MS (LDI-MS) and employed for the LDI-MS-based analysis of glycans and druglike molecules, the quantification of lactose in milk by isotopic dilution, and metabolite imaging on mouse brain tissue samples. PMID:25411795

López de Laorden, Carlos; Beloqui, Ana; Yate, Luis; Calvo, Javier; Puigivila, Maria; Llop, Jordi; Reichardt, Niels-Christian

2015-01-01

341

Mass spectrometry and renal calculi  

PubMed Central

The present review represents a concise and complete survey of the literature covering 2004–2009, concerning the mass spectrometric techniques involved in the structural investigation of renal calculi. After a short presentation of the fundamental mass spectrometric techniques (MALDI–TOF, QTOF, MS–MS) as well as hyphenated methods (GC–MS, LC–MS, CE–MS), an extensive study of the urinary proteome analysis as well as the detection and quantification by mass spectrometry of toxins, drugs and metabolites from renal calculi is presented. PMID:20968197

Purcarea, VL; Sisu, I; Sisu, E

2010-01-01

342

Mass spectrometry and renal calculi  

E-print Network

The present review represents a concise and complete survey of the literature covering 2004-2009, concerning the mass spectrometric techniques involved in the structural investigation of renal calculi. After a short presentation of the fundamental mass spectrometric techniques (MALDI-TOF, QTOF, MS-MS) as well as hyphenated methods (GC-MS, LC-MS, CE-MS), an extensive study of the urinary proteome analysis as well as the detection and quantification by mass spectrometry of toxins, drugs and metabolites from renal calculi is presented.

Mircea Penescu; Victor Lorin Purcarea; Ioana Sisu; Eugen Sisu

343

Mass spectrometry and renal calculi.  

PubMed

The present review represents a concise and complete survey of the literature covering 2004-2009, concerning the mass spectrometric techniques involved in the structural investigation of renal calculi. After a short presentation of the fundamental mass spectrometric techniques (MALDI-TOF, QTOF, MS-MS) as well as hyphenated methods (GC-MS, LC-MS, CE-MS), an extensive study of the urinary proteome analysis as well as the detection and quantification by mass spectrometry of toxins, drugs and metabolites from renal calculi is presented. PMID:20968197

Penescu, Mircea; Purcarea, Victor Lorin; Sisu, Ioana; Sisu, Eugen

2010-01-01

344

Mass spectrometry of aerospace materials  

NASA Technical Reports Server (NTRS)

Mass spectrometry is used for chemical analysis of aerospace materials and contaminants. Years of analytical aerospace experience have resulted in the development of specialized techniques of sampling and analysis which are required in order to optimize results. This work has resulted in the evolution of a hybrid method of indexing mass spectra which include both the largest peaks and the structurally significant peaks in a concise format. With this system, a library of mass spectra of aerospace materials was assembled, including the materials responsible for 80 to 90 percent of the contamination problems at Goddard Space Flight Center during the past several years.

Colony, J. A.

1976-01-01

345

Accelerator mass spectrometry  

SciTech Connect

Accelerator mass spectroscopy (AMS) can be used for efficient detection of long-lived isotopes at part-per-quadrillion sensitivities with good precision. In this article we present an overview of AMS and its recent use in archaeology, geochemistry and biomolecular tracing. All AMS systems use cesium sputter ion sources to produce negative ions from a small button of a solid sample containing the element of interest, such as graphite, metal halide, or metal oxide, often mixed with a metal powder as binder and thermal conductor. Experience shows that both natural and biomedical samples are compatible in a single AMS system, but few other AMS sites make routine {sup 14}C measurements for both dating and tracing. AMS is, in one sense, just `a very sensitive decay counter`, but if AMS sensitivity is creatively coupled to analytical chemistry of certain isotopes, whole new areas of geosciences, archaeology, and life sciences can be explored. 29 refs., 2 figs., 1 tab.

Vogel, J.S.; Turteltaub, K.W.; Finkel, R. [Lawrence Livermore National Lab., CA (United States); Nelson, D.E.

1995-06-01

346

Addition of reagents to the sheath liquid: a novel concept in capillary electrophoresis-mass spectrometry.  

PubMed

Conventional coupling of capillary electrophoresis with electrospray ionisation mass spectrometry typically relies on the use of a triaxial sheath-flow liquid interface to facilitate electrical contact and provide a stable electrospray. In this type of analysis, the use of additives in the sheath liquid itself can also be used to improve ionisation of analytes and even facilitate reactions between separation and detection steps (which we broadly term "sheath-flow chemistry"). In the present work, this concept is demonstrated using two types of sheath-flow reactions for CE coupled with quadrupole time-of-flight (Q-TOF) MS detection. Sheath liquid compositions containing deuterated solvents or DPPH (2,2-diphenyl-1-dipicrylhydrazyl) stable free-radicals yield useful additional structural information for separated analytes. Investigations of fundamental physical and chemical characteristics of the sheath liquid coupling show their direct influence on the efficiency and some of the products of the respective reactions. For example, reducing the capillary internal diameter from 75 to 25?m increased the relative abundance of fully deuterated ions detected by 63-65% (5 exchangeable hydrogens) using constant sheath-flow conditions. Addition of 0.05-0.2mM DPPH to the sheath liquid reduced the peak total ion count obtained for typical antioxidant species by 20 to >95% allowing strongly antioxidant species from mixtures to be readily identified and further studied. The presented approach allows a rapid and information-rich analysis to be performed with minimal reagent and sample consumption. PMID:24751556

Causon, Tim J; Maringer, Leila; Buchberger, Wolfgang; Klampfl, Christian W

2014-05-23

347

Analysis of protein tyrosine phosphatase interactions with microarrayed phosphopeptide substrates using imaging mass spectrometry  

PubMed Central

Microarrays of peptide and recombinant protein libraries are routinely used for high-throughput studies of protein-protein interactions and enzymatic activities. Imaging mass spectrometry (IMS) is currently applied as a method to localize analytes on thin tissue sections and other surfaces. Here, we have applied IMS as a label-free means to analyze protein-peptide interactions in a microarray-based phosphatase assay. This IMS strategy visualizes the entire microarray in one composite image by collecting a pre-defined raster of MALDI-TOF MS spectra over the surface of the chip. Examining the bacterial tyrosine phosphatase YopH, we used IMS as a label-free means to visualize enzyme binding and activity with a microarrayed phosphopeptide library printed on chips coated with either gold or indium-tin oxide. Further, we demonstrate that microarray-based IMS can be coupled with surface plasmon resonance imaging to add kinetic analyses to measured binding interactions. The method described here is within the capabilities of many modern MALDI-TOF instruments and has general utility for the label-free analysis of microarray assays. PMID:23906642

McKee, Christopher J.; Hines, Harry B.; Ulrich, Robert G.

2013-01-01

348

MALDI-TOF mass spectrometry for the monitoring of she-donkey's milk contamination or adulteration.  

PubMed

Donkey's milk (DM), representing a safe and alternative food in both IgE-mediated and non-IgE-mediated cow's milk protein allergy, can be categorized as precious pharma-food. Moreover, an economically relevant interest for the use of DM in cosmetology is also developing. The detection of adulterations and contaminations of DM is a matter of fundamental importance from both an economic and allergenic standpoint, and, to this aim, fast and efficient analytical approaches to assess the authenticity of this precious nutrient are desirable. Here, a rapid matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS)-based method aimed to the detection of bovine or caprine milk in raw DM is reported. The presence of the extraneous milks was revealed by monitoring the protein profiles of the most abundant whey proteins, ?-lactalbumin (?-LA) and ?-lactoglobulin, used as molecular markers. The possibility of obtaining a quantitative analysis of the level of cow or goat milk in DM based on the MALDI-TOF peak areas of ?-LAs was also explored. The results showed that the experimental quantitative values were in good agreement with the real composition of each mixture. As pretreatment of the milk samples is not required, and owing to the speed and the high sensitivity of MALDI-MS, the protocol here reported could represent a reliable method for routine analyses aimed to assess the absence of contamination in raw fresh DM samples. PMID:23378086

Cunsolo, Vincenzo; Muccilli, Vera; Saletti, Rosaria; Foti, Salvatore

2013-02-01

349

Metabolite profiling of hemodialysate using gas chromatography time-of-flight mass spectrometry.  

PubMed

Hemodialysis is an important alternative for renal replacement therapy to remove uremic retention solutes (URS) for the uremic syndrome. The metabolites in the hemodialysate directly reflect the efficiency of URS clearance. Here we report a highly sensitive and reliable metabolomic procedure for the measurement of small molecule metabolites in hemodialysate using gas chromatography coupled with time-of-flight mass spectrometry (GC/TOF/MS). The method was developed and evaluated through orthogonal experimental design using multivariate statistical analysis. The optimized method involves the use of methanol and water in the ratio of 3:1 (v/v) for dissolving the lyophilized solid of the hemodialysate after degradation of urea with urease (no less than 50U) for 10min. Validation of the method demonstrated a good linearity with regression coefficients greater than 0.99. Relative standard deviations of precision and stability of proposed method were less than 15%, and recoveries ranged from 71.8 to 115.8%. This method was successfully applied in the metabolite profiling of human hemodialysate samples which was able to differentiate the patients treated with high-flux hemodialysis from those with low-flux hemodialysis. The metabolomic results reveal a higher concentration of URS, and thus, better URS removal, from the patients under high-flux dialysis than those under low-flux dialysis. PMID:21530126

Qi, Xin; Zhang, Yinan; Gao, Jiayuan; Chen, Tianlu; Zhao, Aihua; Yan, Yucheng; Jia, Wei

2011-07-15

350

The coupling of direct analysis in real time ionization to Fourier transform ion cyclotron resonance mass spectrometry for ultrahigh-resolution mass analysis.  

PubMed

Direct Analysis in Real Time (DART) is an ambient ionization technique for mass spectrometry that provides rapid and sensitive analyses with little or no sample preparation. DART has been reported primarily for mass analyzers of low to moderate resolving power such as quadrupole ion traps and time-of-flight (TOF) mass spectrometers. In the current work, a custom-built DART source has been successfully coupled to two different Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers for the first time. Comparison of spectra of the isobaric compounds, diisopropyl methylphosphonate and theophylline, acquired by 4.7 T FT-ICR MS and TOF MS, demonstrates that the TOF resolving power can be insufficient for compositionally complex samples. 9.4 T FT-ICR MS yielded the highest mass resolving power yet reported with DART ionization for 1,2-benzanthracene and 9,10-diphenylanthracene. Polycyclic aromatic hydrocarbons exhibit a spatial dependence in ionization mechanisms between the DART source and the mass spectrometer. The feasibility of analyzing a variety of samples was established with the introduction and analysis of food products and crude oil samples. DART FT-ICR MS provides complex sample analysis that is rapid, highly selective and information-rich, but limited to relatively low-mass analytes. PMID:20187081

Rummel, Julia L; McKenna, Amy M; Marshall, Alan G; Eyler, John R; Powell, David H

2010-03-01

351

Quantification, confirmation and screening capability of UHPLC coupled to triple quadrupole and hybrid quadrupole time-of-flight mass spectrometry in pesticide residue analysis.  

PubMed

The potential of three mass spectrometry (MS) analyzers (triple quadrupole, QqQ; time of flight, TOF; and quadrupole time of flight, QTOF) has been investigated and compared for quantification, confirmation and screening purposes in pesticide residue analysis of fruit and vegetable samples. For this purpose, analytical methodology for multiresidue determination of 11 pesticides, taken as a model, has been developed and validated in nine food matrices for the three mass analyzers coupled to ultra high pressure liquid chromatography. In all cases, limits of quantification around 0.01 mg/kg were reached, fulfilling the most restrictive case of baby-food analysis. Regarding absolute sensitivity, the lower limits of detection were obtained, as expected, for QqQ (100 fg), whereas slightly higher limits (300 fg) were obtained for both TOF and QTOF. Confirmative capacity of each analyzer was studied for each analyte based on the identification points (IPs) criterion, useful for a comprehensive comparison. QTOF mass analyzer showed the highest confirmatory capacity, although QqQ normally led to sufficient number of IPs, even at lower concentration levels. The potential of TOF MS was also investigated for screening purposes. To this aim, around 50 commercial fruits and vegetables samples were analyzed, searching for more than 400 pesticides. TOF MS proved to be an attractive analytical tool for rapid detection and reliable identification of a large number of pesticides thanks to the full spectrum acquisition at accurate mass with satisfactory sensitivity. This process is readily boosted when combined with specialized software packages, together with theoretical exact mass databases. Several pesticides (e.g. carbendazim in citrus and indoxacarb in grape) were detected in the samples. Further unequivocal confirmation of the identity was performed using reference standards and/or QTOF MS/MS experiments. PMID:20301091

Grimalt, Susana; Sancho, Juan V; Pozo, Oscar J; Hernández, Félix

2010-04-01

352

Surface pretreatment effects on titanium chips for the adhesion of pathogenic bacteria in the MALDI-TOF MS  

NASA Astrophysics Data System (ADS)

The effect of surface pretreatment methodologies on subsequent oxide film formation and their surface properties is reported. The influence of hydrophobicity and hydrophilicity on the attachment/detection of pathogenic bacteria to titanium chip is also investigated. The results show that the Staphylococcus aureus preferred hydrophilic surfaces and also had an affinity for the non-heat treated (control) titanium surfaces. Laser ablation resulted in significant improvement in the attachment of both pathogenic bacteria. The bacteria attached to the modified titanium chips surface were analyzed by MALDI-TOF MS. Thus, this study demonstrates that modifying the surface by various surfaces pretreatment such as heat treatments and laser ablation could lead to selective capture of either Pseudomonas aeruginosa or Staphylococcus aureus by the titanium chips. This study is for direct and effective detection of pathogenic bacteria using MALDI-TOF MS.

Hasan, Nazim; Gopal, Judy; Wu, Hui-Fen

2014-09-01

353

Mass spectrometry. [review of techniques  

NASA Technical Reports Server (NTRS)

Advances in mass spectrometry (MS) and its applications over the past decade are reviewed in depth, with annotated literature references. New instrumentation and techniques surveyed include: modulated-beam MS, chromatographic MS on-line computer techniques, digital computer-compatible quadrupole MS, selected ion monitoring (mass fragmentography), and computer-aided management of MS data and interpretation. Areas of application surveyed include: organic MS and electron impact MS, field ionization kinetics, appearance potentials, translational energy release, studies of metastable species, photoionization, calculations of molecular orbitals, chemical kinetics, field desorption MS, high pressure MS, ion cyclotron resonance, biochemistry, medical/clinical chemistry, pharmacology, and environmental chemistry and pollution studies.

Burlingame, A. L.; Kimble, B. J.; Derrick, P. J.

1976-01-01

354

Detection and quantification of the Bcr/Abl chimeric protein on biochips using LDI-TOF MS.  

PubMed

The Bcr/Abl chimeric protein was captured by two antibodies, anti-Bcr on gold nanoparticles (AuNPs) and anti-Abl on a biochip, in a sandwich assay format. The presence of the Bcr/Abl in cells was then verified by amplified LDI-TOF MS signals, and relative amounts were quantified using AuNPs coated with deuterated alkanethiols as an internal standard. PMID:24686900

Hong, Seol-Hye; Kim, Jae Il; Kang, Hyunook; Yoon, Soojin; Kim, Dong-Eun; Jung, Woong; Yeo, Woon-Seok

2014-05-14

355

Metabolomics using GC-TOF-MS followed by subsequent GC-FID and HILIC-MS/MS analysis revealed significantly altered fatty acid and phospholipid species profiles in plasma of smokers.  

PubMed

Mass spectrometry is an ideal tool for investigations of the metabolome in human plasma. To investigate the impact of smoking on the human metabolome, we performed an untargeted metabolic fingerprinting using GC-TOF-MS with EDTA-plasma samples from 25 smokers and 25 non-smokers. The observed elevated levels in the monounsaturated fatty acids (MUFAs) in smokers were verified by a targeted analysis using GC-FID, which revealed also significantly alterations in saturated and polyunsaturated fatty acids in smokers (p<0.05, Mann-Whitney U test). Since the main fraction of fatty acids in plasma is esterified to phospholipids, we analyzed phosphatidylcholine (PC) and phosphatidylethanolamine (PE) species composition in the plasma samples of the same subjects. The profiles of 39 PC and 40 PE species were analyzed with a newly developed and validated HILIC-ESI-MS/MS method. We were able to baseline separate the two lipid classes (PC from PE) by maintaining co-elution of individual lipid species of each class. The method shows a linear range from 0.5?M to 2000?M and an inter- and intraday coefficient of variation (CV)<20% across all analytes. Application of the validated method to the plasma samples of smokers and non-smokers, derived from a diet-controlled smoking study, revealed significantly elevated levels of PC and PE species containing MUFAs in smokers. In summary, we could demonstrate that there is a significantly altered total fatty acid profile, with increased MUFAs, in the plasma of smokers compared to non-smokers. Results obtained with the new HILIC-MS/MS method indicate that the altered fatty acid profile is also reflected in the PC and PE profile of smokers. PMID:24630914

Müller, Daniel C; Degen, Christian; Scherer, Gerhard; Jahreis, Gerhard; Niessner, Reinhard; Scherer, Max

2014-09-01

356

A mass spectrometry primer for mass spectrometry imaging  

PubMed Central

Mass spectrometry imaging (MSI), a rapidly growing subfield of chemical imaging, employs mass spectrometry (MS) technologies to create single- and multi-dimensional localization maps for a variety of atoms and molecules. Complimentary to other imaging approaches, MSI provides high chemical specificity and broad analyte coverage. This powerful analytical toolset is capable of measuring the distribution of many classes of inorganics, metabolites, proteins and pharmaceuticals in chemically and structurally complex biological specimens in vivo, in vitro, and in situ. The MSI approaches highlighted in this Methods in Molecular Biology volume provide flexibility of detection, characterization, and identification of multiple known and unknown analytes. The goal of this chapter is to introduce investigators who may be unfamiliar with MS to the basic principles of the mass spectrometric approaches as used in MSI. In addition to guidelines for choosing the most suitable MSI method for specific investigations, cross-references are provided to the chapters in this volume that describe the appropriate experimental protocols. PMID:20680583

Rubakhin, Stanislav S.; Sweedler, Jonathan V.

2011-01-01

357

Interlaboratory comparison of sample preparation methods, database expansions, and cutoff values for identification of yeasts by matrix-assisted laser desorption ionization-time of flight mass spectrometry using a yeast test panel.  

PubMed

An interlaboratory study using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to determine the identification of clinically important yeasts (n = 35) was performed at 11 clinical centers, one company, and one reference center using the Bruker Daltonics MALDI Biotyper system. The optimal cutoff for the MALDI-TOF MS score was investigated using receiver operating characteristic (ROC) curve analyses. The percentages of correct identifications were compared for different sample preparation methods and different databases. Logistic regression analysis was performed to analyze the association between the number of spectra in the database and the percentage of strains that were correctly identified. A total of 5,460 MALDI-TOF MS results were obtained. Using all results, the area under the ROC curve was 0.95 (95% confidence interval [CI], 0.94 to 0.96). With a sensitivity of 0.84 and a specificity of 0.97, a cutoff value of 1.7 was considered optimal. The overall percentage of correct identifications (formic acid-ethanol extraction method, score ? 1.7) was 61.5% when the commercial Bruker Daltonics database (BDAL) was used, and it increased to 86.8% by using an extended BDAL supplemented with a Centraalbureau voor Schimmelcultures (CBS)-KNAW Fungal Biodiversity Centre in-house database (BDAL+CBS in-house). A greater number of main spectra (MSP) in the database was associated with a higher percentage of correct identifications (odds ratio [OR], 1.10; 95% CI, 1.05 to 1.15; P < 0.01). The results from the direct transfer method ranged from 0% to 82.9% correct identifications, with the results of the top four centers ranging from 71.4% to 82.9% correct identifications. This study supports the use of a cutoff value of 1.7 for the identification of yeasts using MALDI-TOF MS. The inclusion of enough isolates of the same species in the database can enhance the proportion of correctly identified strains. Further optimization of the preparation methods, especially of the direct transfer method, may contribute to improved diagnosis of yeast-related infections. PMID:24920782

Vlek, Anneloes; Kolecka, Anna; Khayhan, Kantarawee; Theelen, Bart; Groenewald, Marizeth; Boel, Edwin; Boekhout, Teun

2014-08-01

358

Classification of Ancient Mammal Individuals Using Dental Pulp MALDI-TOF MS Peptide Profiling  

PubMed Central

Background The classification of ancient animal corpses at the species level remains a challenging task for forensic scientists and anthropologists. Severe damage and mixed, tiny pieces originating from several skeletons may render morphological classification virtually impossible. Standard approaches are based on sequencing mitochondrial and nuclear targets. Methodology/Principal Findings We present a method that can accurately classify mammalian species using dental pulp and mass spectrometry peptide profiling. Our work was organized into three successive steps. First, after extracting proteins from the dental pulp collected from 37 modern individuals representing 13 mammalian species, trypsin-digested peptides were used for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. The resulting peptide profiles accurately classified every individual at the species level in agreement with parallel cytochrome b gene sequencing gold standard. Second, using a 279–modern spectrum database, we blindly classified 33 of 37 teeth collected in 37 modern individuals (89.1%). Third, we classified 10 of 18 teeth (56%) collected in 15 ancient individuals representing five mammal species including human, from five burial sites dating back 8,500 years. Further comparison with an upgraded database comprising ancient specimen profiles yielded 100% classification in ancient teeth. Peptide sequencing yield 4 and 16 different non-keratin proteins including collagen (alpha-1 type I and alpha-2 type I) in human ancient and modern dental pulp, respectively. Conclusions/Significance Mass spectrometry peptide profiling of the dental pulp is a new approach that can be added to the arsenal of species classification tools for forensics and anthropology as a complementary method to DNA sequencing. The dental pulp is a new source for collagen and other proteins for the species classification of modern and ancient mammal individuals. PMID:21364886

Tran, Thi-Nguyen-Ny; Aboudharam, Gérard; Gardeisen, Armelle; Davoust, Bernard; Bocquet-Appel, Jean-Pierre; Flaudrops, Christophe; Belghazi, Maya; Raoult, Didier; Drancourt, Michel

2011-01-01

359

Rapid identification of coumarins from Fructus citri Sarcodactylis by UPLC/Q-TOF-MS.  

PubMed

Coumarins is a kind of important components in traditional Chinese medicine. Due to their special structure, they have significant pathological connections with many diseases. In this research, we established a rapid method to analyse the coumarins from Fructus citri Sarcodactylis by using the technique of ultra-performance liquid chromatography with quadruple time-of-flight mass spectrometry. Twenty-one coumarins were identified from Fructus citri Sarcodactylis, 10 were discovered for the first time. At the same time, a rapid sensitive method for identifying coumarins from Fructus citri Sarcodactylis was established. PMID:25253205

Yanmei, Zhong; Yifan, Feng; Xia, Wu; Jiao, Guo

2015-01-01

360

Electrophoresis-mass spectrometry probe  

DOEpatents

The invention involves a new technique for the separation of complex mixtures of chemicals, which utilizes a unique interface probe for conventional mass spectrometers which allows the electrophoretically separated compounds to be analyzed in real-time by a mass spectrometer. This new chemical analysis interface, which couples electrophoresis with mass spectrometry, allows complex mixtures to be analyzed very rapidly, with much greater specificity, and with greater sensitivity. The interface or probe provides a means whereby large and/or polar molecules in complex mixtures to be completely characterized. The preferred embodiment of the probe utilizes a double capillary tip which allows the probe tip to be continually wetted by the buffer, which provides for increased heat dissipation, and results in a continually operating interface which is more durable and electronically stable than the illustrated single capillary tip probe interface. 8 figs.

Andresen, B.D.; Fought, E.R.

1987-11-10

361

Establishment of a matrix-assisted laser desorption ionization time-of-flight mass spectrometry database for rapid identification of infectious achlorophyllous green micro-algae of the genus Prototheca.  

PubMed

The possibility of using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for rapid identification of pathogenic and non-pathogenic species of the genus Prototheca has been recently demonstrated. A unique reference database of MALDI-TOF MS profiles for type and reference strains of the six generally accepted Prototheca species was established. The database quality was reinforced after the acquisition of 27 spectra for selected Prototheca strains, with three biological and technical replicates for each of 18 type and reference strains of Prototheca and four strains of Chlorella. This provides reproducible and unique spectra covering a wide m/z range (2000-20?000?Da) for each of the strains used in the present study. The reproducibility of the spectra was further confirmed by employing composite correlation index calculation and main spectra library (MSP) dendrogram creation, available with MALDI Biotyper software. The MSP dendrograms obtained were comparable with the 18S rDNA sequence-based dendrograms. These reference spectra were successfully added to the Bruker database, and the efficiency of identification was evaluated by cross-reference-based and unknown Prototheca identification. It is proposed that the addition of further strains would reinforce the reference spectra library for rapid identification of Prototheca strains to the genus and species/genotype level. PMID:21781208

Murugaiyan, J; Ahrholdt, J; Kowbel, V; Roesler, U

2012-05-01

362

An empirical Bayes model using a competition score for metabolite identification in gas chromatography mass spectrometry  

PubMed Central

Background Mass spectrometry (MS) based metabolite profiling has been increasingly popular for scientific and biomedical studies, primarily due to recent technological development such as comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC/TOF-MS). Nevertheless, the identifications of metabolites from complex samples are subject to errors. Statistical/computational approaches to improve the accuracy of the identifications and false positive estimate are in great need. We propose an empirical Bayes model which accounts for a competing score in addition to the similarity score to tackle this problem. The competition score characterizes the propensity of a candidate metabolite of being matched to some spectrum based on the metabolite's similarity score with other spectra in the library searched against. The competition score allows the model to properly assess the evidence on the presence/absence status of a metabolite based on whether or not the metabolite is matched to some sample spectrum. Results With a mixture of metabolite standards, we demonstrated that our method has better identification accuracy than other four existing methods. Moreover, our method has reliable false discovery rate estimate. We also applied our method to the data collected from the plasma of a rat and identified some metabolites from the plasma under the control of false discovery rate. Conclusions We developed an empirical Bayes model for metabolite identification and validated the method through a mixture of metabolite standards and rat plasma. The results show that our hierarchical model improves identification accuracy as compared with methods that do not structurally model the involved variables. The improvement in identification accuracy is likely to facilitate downstream analysis such as peak alignment and biomarker identification. Raw data and result matrices can be found at http://www.biostat.iupui.edu/~ChangyuShen/index.htm Trial Registration 2123938128573429 PMID:21985394

2011-01-01