共查询到20条相似文献,搜索用时 31 毫秒
1.
Maria R. Plata Cosima Koch Patrick Wechselberger Christoph Herwig Bernhard Lendl 《Analytical and bioanalytical chemistry》2013,405(25):8241-8250
A fast and simple method to control variations in carbohydrate composition of Saccharomyces cerevisiae, baker's yeast, during fermentation was developed using mid-infrared (mid-IR) spectroscopy. The method allows for precise and accurate determinations with minimal or no sample preparation and reagent consumption based on mid-IR spectra and partial least squares (PLS) regression. The PLS models were developed employing the results from reference analysis of the yeast cells. The reference analyses quantify the amount of trehalose, glucose, glycogen, and mannan in S. cerevisiae. The selection and optimization of pretreatment steps of samples such as the disruption of the yeast cells and the hydrolysis of mannan and glycogen to obtain monosaccharides were carried out. Trehalose, glucose, and mannose were determined using high-performance liquid chromatography coupled with a refractive index detector and total carbohydrates were measured using the phenol–sulfuric method. Linear concentration range, accuracy, precision, LOD and LOQ were examined to check the reliability of the chromatographic method for each analyte. Figure
Comparison of workflows for carbohydrate determination in S.cerevisiae by FT-IR spectroscopy and HPLC-RI 相似文献
2.
Alan L. Rockwood John C. L. Erve 《Journal of the American Society for Mass Spectrometry》2014,25(12):2163-2176
Distortions of peaks can occur when one uses the standard method of signal processing of data from the Orbitrap and other FT-based methods of mass spectrometry. These distortions arise because the standard method of signal processing is not a linear process. If one adds two or more functions, such as time-dependent signals from a Fourier transform mass spectrometer and performs a linear operation on the sum, the result is the same as if the operation was performed on separate functions and the results added. If this relationship is not valid, the operation is non-linear and can produce unexpected and/or distorted results. Although the Fourier transform itself is a linear operator, the standard algorithm for processing spectra in Fourier transform-based methods include non-linear mathematical operators such that spectra processed by the standard algorithm may become distorted. The most serious consequence is that apparent abundances of the peaks in the spectrum may be incorrect. In light of these considerations, we performed theoretical modeling studies to illustrate several distortion effects that can be observed, including abundance distortions. In addition, we discuss experimental systems where these effects may manifest, including suggested systems for study that should demonstrate these peak distortions. Finally, we point to several examples in the literature where peak distortions may be rationalized by the phenomena presented here. Graphical Abstract
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3.
Lukáš Gál Michal Čeppan Milena Reháková Vladimír Dvonka Jarmila Tarajčáková Jozef Hanus 《Analytical and bioanalytical chemistry》2013,405(28):9085-9091
A method has been developed for identification of corrosive iron–gall inks in historical drawings and documents. The method is based on target-factor analysis of visible–near infrared fibre optic reflection spectra (VIS–NIR FORS). A set of reference spectra was obtained from model samples of laboratory-prepared inks covering a wide range of mixing ratios of basic ink components deposited on substrates and artificially aged. As criteria for correspondence of a studied spectrum with a reference spectrum, the apparent error in target (AET) and the empirical function SPOIL according to Malinowski were used. The capability of the proposed tool to distinguish corrosive iron–gall inks from bistre and sepia inks was evaluated by use of a set of control samples of bistre, sepia, and iron–gall inks. Examples are presented of analysis of historical drawings from the 15th and 16th centuries and written documents from the 19th century. The results of analysis based on the tool were confirmed by XRF analysis and colorimetric spot analysis. Figure
Sitting Evangelist, Bartolomeo Passarotti, 16th century, Slovak National Gallery, Bratislava, Slovak Republic, Inventory No. K 96 相似文献
4.
A novel approach utilizing automated Raman microspectroscopic mapping for gunshot residue (GSR) detection was investigated. A well-established technique for GSR recovery (tape lifting) was utilized for GSR particle collection. Uncontaminated samples of the substrate (tape), organic GSR (OGSR), and inorganic GSR (IGSR) particles were characterized to generate three respective Raman spectroscopic training sets. Automated Raman mapping was used to rapidly collect spectra over areas of the tape substrate populated with GSR particles. Raman spectra collected from the maps were classified against the training sets via partial least squares discriminant analysis (PLS-DA) to determine if GSR was present. We report the application of Raman chemical mapping as a proof of concept for the positive detection of GSR particles of varying morphologies. The estimated size of GSR particles, which could be readily detected by this method, is about 3.4 μm. The efficiency of the classification was quantitated with rates of true positives and negatives. Validation studies scrutinizing the practicality of this approach as a viable tool for potential forensics investigations are currently in progress. Figure
The figure illustrates a novel approach for the recovery and identification of gunshot residue on adhesive tape. The emerging approach combines tape lifting and a rapid, non-destructive Raman spectroscopic scanning over the tape, which was used for collecting GSR from a surface of interest. Detection of GSR is achieved through multivariate classification of mapping spectra against a known training set. 相似文献
5.
Dennis Kaufhold Janosch Fagaschewski Daniel Sellin Simon Strompen Andreas Liese Lutz Hilterhaus 《Analytical and bioanalytical chemistry》2014,406(13):3157-3166
Monitoring the dispersed phase of an oil-in-water (O–W) emulsion by means of Fourier transform infrared (FTIR) spectroscopy is a challenging task, restricted to the continuous phase that is in contact with the FTIR probe. Nonetheless, real-time measurement and kinetic analysis by FTIR, including analysis of the dispersed, often non-polar phase containing substrates and/or products, is desirable. Enzymatic hydrolysis of sunflower oil was performed in an O–W emulsion. After separation of the oil phase by use of a newly developed μ-membrane module, infrared spectra were collected using an attenuated total reflectance (ATR) cell. Different chemometric models were calibrated using the partial least squares (PLS) algorithm. Online application of a chemometric model based on the FTIR spectra enabled real-time monitoring of free fatty acid concentrations in the oil phase. Figure
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6.
Mingjie Tang Gerald D. McEwen Yangzhe Wu Charles D. Miller Anhong Zhou 《Analytical and bioanalytical chemistry》2013,405(5):1577-1591
The molecular composition of mycobacteria and Gram-negative bacteria cell walls is structurally different. In this work, Raman microspectroscopy was applied to discriminate mycobacteria and Gram-negative bacteria by assessing specific characteristic spectral features. Analysis of Raman spectra indicated that mycobacteria and Gram-negative bacteria exhibit different spectral patterns under our experimental conditions due to their different biochemical components. Fourier transform infrared (FTIR) spectroscopy, as a supplementary vibrational spectroscopy, was also applied to analyze the biochemical composition of the representative bacterial strains. As for co-cultured bacterial mixtures, the distribution of individual cell types was obtained by quantitative analysis of Raman and FTIR spectral images and the spectral contribution from each cell type was distinguished by direct classical least squares analysis. Coupled atomic force microscopy (AFM) and Raman microspectroscopy realized simultaneous measurements of topography and spectral images for the same sampled surface. This work demonstrated the feasibility of utilizing a combined Raman microspectroscopy, FTIR, and AFM techniques to effectively characterize spectroscopic fingerprints from bacterial Gram types and mixtures. Figure
AFM deflection images, Raman spectra, SEM images, and FTIR of Mycobacterium sp. KMS 相似文献
7.
Valeria Di Tullio Donatella Capitani Federica Presciutti Gennaro Gentile Brunetto Giovanni Brunetti Noemi Proietti 《Analytical and bioanalytical chemistry》2013,405(26):8669-8675
NMR stratigraphy was used to investigate in situ, non-destructively and non-invasively, the stratigraphy of hydrogen-rich layers of an ancient Nubian detached mural painting. Because of the detachment procedure, a complex multi-layered artefact was obtained, where, besides layers of the original mural painting, also the materials used during the procedure all became constitutive parts of the artefact. NMR measurements in situ enabled monitoring of the state of conservation of the artefact and planning of minimum representative sampling to validate results obtained in situ by solid-state NMR analysis of the samples. This analysis enabled chemical characterization of all organic materials. Use of reference compounds and prepared specimens assisted data interpretation. Figure
Right side, portable NMR scanning an ancient detached mural painting, left side NMR stratigraphy of a region of the painting 相似文献
8.
Valery G. Voinov Samuel E. Bennett Joseph S. Beckman Douglas F. Barofsky 《Journal of the American Society for Mass Spectrometry》2014,25(10):1730-1738
A radio frequency-free electromagnetostatic (EMS) cell devised for electron-capture dissociation (ECD) of ions has been retrofitted into the collision-induced dissociation (CID) section of a triple quadrupole mass spectrometer to enable recording of ECD product-ion mass spectra and simultaneous recording of ECD-CID product-ion mass spectra. This modified instrument can be used to produce easily interpretable ECD and ECD-CID product-ion mass spectra of tyrosine-phosphorylated peptides that cover over 50% of their respective amino-acid sequences and readily identify their respective sites of phosphorylation. ECD fragmentation of doubly protonated, tyrosine-phosphorylated peptides, which was difficult to observe with FT-ICR instruments, occurs efficiently in the EMS cell. Figure
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9.
Ligia Maria Moretto Francesca Montagner Renzo Ganzerla Paolo Ugo 《Analytical and bioanalytical chemistry》2013,405(11):3603-3610
Voltammetry of microparticles is applied to characterise and to identify solid analytes of interest in the field of cultural heritage. Nafion® is used for the immobilisation of solid microparticles onto the surface of a glassy carbon electrode by exploiting the deposition onto the electrode surface of a micro-volume of a suspension of the microsample in polymeric solution. Cyclic voltammetry and square wave voltammetry are applied to characterise and to identify the microparticles immobilised in the Nafion® coating. The analyte studied in this work is Prussian Blue as a typical inorganic pigment, with a relatively simple electrochemical behaviour. The proposed method is applied to a sample of Venetian marmorino plaster. The performance of Nafion® for this analysis is compared with that of the polymer Paraloid B72. Figure
From sampling the pigment in the work of art to recording the voltammetric signal with Nafion coated electrodes 相似文献
10.
Katia Wehbe Jacob Filik Mark D. Frogley Gianfelice Cinque 《Analytical and bioanalytical chemistry》2013,405(4):1311-1324
The study of individual cells with infrared (IR) microspectroscopy often requires living cells to be cultured directly onto a suitable substrate. The surface effect of the specific substrates on the cell growth—viability and associated biochemistry—as well as on the IR analysis—spectral interference and optical artifacts—is all too often ignored. Using the IR beamline, MIRIAM (Diamond Light Source, UK), we show the importance of the substrate used for IR absorption spectroscopy by analyzing two different cell lines cultured on a range of seven optical substrates in both transmission and reflection modes. First, cell viability measurements are made to determine the preferable substrates for normal cell growth. Successively, synchrotron radiation IR microspectroscopy is performed on the two cell lines to determine any genuine biochemically induced changes or optical effect in the spectra due to the different substrates. Multivariate analysis of spectral data is applied on each cell line to visualize the spectral changes. The results confirm the advantage of transmission measurements over reflection due to the absence of a strong optical standing wave artifact which amplifies the absorbance spectrum in the high wavenumber regions with respect to low wavenumbers in the mid-IR range. The transmission spectra reveal interference from a more subtle but significant optical artifact related to the reflection losses of the different substrate materials. This means that, for comparative studies of cell biochemistry by IR microspectroscopy, it is crucial that all samples are measured on the same substrate type. Figure
Cell separation by PCA due to the refractive index of the substrate used, revealing transmission artifact. 相似文献
11.
Identification of animal glue and hen-egg yolk in paintings by use of enzyme-linked immunosorbent assay (ELISA) 总被引:1,自引:0,他引:1
M. Palmieri M. Vagnini L. Pitzurra B. G. Brunetti L. Cartechini 《Analytical and bioanalytical chemistry》2013,405(19):6365-6371
We report the development of an indirect ELISA procedure for specific identification of chicken-egg yolk and animal glues in painting micro-samples. The results presented integrate previously published work on ELISA recognition of bovine β-casein and chicken ovalbumin in painting materials. The integrated final ELISA procedure—optimised for protein extraction, immuno-reagent concentrations, blocking solution, incubation time, and temperature—enables multiplex identification, in single samples, of proteinaceous materials, i.e. chicken-egg yolk and albumen, animal glues, and bovine milk and/or casein, mainly used by painters in the past. The procedure has been systematically tested on laboratory models of mural and easel paintings, both naturally and artificially aged, to assess possible inhibitory effects on the immuno-reaction caused by inorganic painting materials (pigments and substrates) and by protein degradation resulting from aging processes. Real samples from case studies, which had previously been investigated and characterised by spectroscopy and chromatography, were successfully studied by use of the developed ELISA procedure. The commercial availability of all the immuno-reagents used, the affordable analytical equipment, and the specificity, sensitivity, and rapidity of ELISA make this method very attractive to diagnostic laboratories in the field of cultural heritage science. Possible further developments to the analytical potential of this technique include improvement of antibody performance and inclusion of other classes of bio-molecules as analytical targets. Figure
An ELISA indirect procedure is reported for the specific identification of chicken egg-yolk and animal glues in micro-samples from historical paintings; the method was experimented on laboratory models of mural and easel paintings, both naturally and artificially aged 相似文献
12.
Yulin Qi Huilin Li Rebecca H. Wills Pilar Perez-Hurtado Xiang Yu David P. A. Kilgour Mark P. Barrow Cheng Lin Peter B. O’Connor 《Journal of the American Society for Mass Spectrometry》2013,24(6):828-834
The method of phasing broadband Fourier transform ion cyclotron resonance (FT-ICR) spectra allows plotting the spectra in the absorption-mode; this new approach significantly improves the quality of the data at no extra cost. Herein, an internal calibration method for calculating the phase function has been developed and successfully applied to the top-down spectra of modified proteins, where the peak intensities vary by 100×. The result shows that the use of absorption-mode spectra allows more peaks to be discerned within the recorded data, and this can reveal much greater information about the protein and modifications under investigation. In addition, noise and harmonic peaks can be assigned immediately in the absorption-mode. Figure
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13.
Rosa Pilolli Nicoletta Ditaranto Nicola Cioffi Luigia Sabbatini 《Analytical and bioanalytical chemistry》2013,405(2-3):713-724
In the present, contribution angle-resolved X-ray photoelectron spectroscopy (AR-XPS) was proposed as a useful tool to address the challenge of probing the near-surface region of bio-active sensor surfaces. A model bio-functionalised surface was characterised by parallel AR-XPS and commercially available Thermo Avantage-ARProcess software was used to generate non-destructive concentration depth profiles of protein-functionalised silicon oxide substrates. At each step of the functionalisation procedure, the surface composition, the overlayer thickness, the in-depth organisation and the in-plane homogeneity were evaluated. The critical discussion of the generated profiles highlighted the relevance of the information provided by PAR-XPS technique. Figure
Schematic representation of the functionalization procedure along with the generated profiles 相似文献
14.
Imran I. Patel Wesley J. Harrison Jemma G. Kerns Jacob Filik Katia Wehbe Paul L. Carmichael Andrew D. Scott Mike P. Philpott Mark D. Frogley Gianfelice Cinque Francis L. Martin 《Analytical and bioanalytical chemistry》2012,404(6-7):1745-1758
Normal function and physiology of the epidermis is maintained by the regenerative capacity of this tissue via adult stem cells (SCs). However, definitive identifying markers for SCs remain elusive. Infrared (IR) spectroscopy exploits the ability of cellular biomolecules to absorb in the mid-IR region (λ?=?2.5–25?μm), detecting vibrational transitions of chemical bonds. In this study, we exploited the cell’s inherent biochemical composition to discriminate SCs of the inter-follicular skin epidermis based on IR-derived markers. Paraffin-embedded samples of human scalp skin (n?=?4) were obtained, and 10-μm thick sections were mounted for IR spectroscopy. Samples were interrogated in transmission mode using synchrotron radiation-based Fourier-transform IR (FTIR) microspectroscopy (15?×?15?μm) and also imaged employing globar-source FTIR focal plane array (FPA) imaging (5.4?×?5.4?μm). Dependent on the location of derived spectra, wavenumber–absorbance/intensity relationships were examined using unsupervised principal component analysis. This approach showed clear separation and spectral differences dependent on cell type. Spectral biomarkers concurrently associated with segregation of SCs, transit-amplifying cells and terminally-differentiated cells of epidermis were primarily PO 2 ? vibrational modes (1,225 and 1,080?cm?1), related to DNA conformational alterations. FPA imaging coupled with hierarchical cluster analysis also indicated the presence of specific basal layer cells potentially originating from the follicular bulge, suggested by co-clustering of spectra. This study highlights PO 2 ? vibrational modes as potential putative SC markers. Figure
“Delineating the putative stem cell lineage in interfollicular skin based on position-derived infrared spectral fingerprints”. 相似文献
15.
Kirsty McKay Tara L. Salter Andrew Bowfield James L. Walsh Ian S. Gilmore James W. Bradley 《Journal of the American Society for Mass Spectrometry》2014,25(9):1528-1537
Plasma-based desorption/ionization sources are an important ionization technique for ambient surface analysis mass spectrometry. In this paper, we compare and contrast three competing plasma based desorption/ionization sources: a radio-frequency (rf) plasma needle, a dielectric barrier plasma jet, and a low-temperature plasma probe. The ambient composition of the three sources and their effectiveness at analyzing a range of pharmaceuticals and polymers were assessed. Results show that the background mass spectrum of each source was dominated by air species, with the rf needle producing a richer ion spectrum consisting mainly of ionized water clusters. It was also seen that each source produced different ion fragments of the analytes under investigation: this is thought to be due to different substrate heating, different ion transport mechanisms, and different electric field orientations. The rf needle was found to fragment the analytes least and as a result it was able to detect larger polymer ions than the other sources. Figure
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16.
Weiqi Fu Manuela Magnúsdóttir Sigureur Brynjólfson Bernhard ?. Palsson Giuseppe Paglia 《Analytical and bioanalytical chemistry》2012,404(10):3145-3154
A fast method for quantification and identification of carotenoid and chlorophyll species utilizing liquid chromatography coupled with UV detection and mass spectrometry has been demonstrated and validated for the analysis of algae samples. This method allows quantification of targeted pigments and identification of unexpected compounds, providing isomers separation, UV detection, accurate mass measurements, and study of fragment ions for structural elucidation in a single run. This is possible using parallel alternating low- and high-energy collision spectral acquisition modes, which provide accurate mass full scan chromatograms and accurate mass high-energy chromatograms. Here, it is shown how this approach can be used to confirm carotenoid and chlorophyll species by identification of key diagnostic fragmentations during high-energy mode. The developed method was successfully applied for the analysis of Dunaliella salina samples during defined red LED lighting growth conditions, identifying 37 pigments including 19 carotenoid species and 18 chlorophyll species, and providing quantification of 7 targeted compounds. Limit of detections for targeted pigments ranged from 0.01?ng/mL for lutein to 0.24?ng/mL for chlorophyll a. Inter-run precision ranged for of 3 to 24 (RSD%) while inter-run inaccuracy ranged from ?17 to 11. Figure
Identification of carotenoids and chlorophylls combining UPLC separation, UV detection, accurate mass measurements and study of fragment ions in a single run 相似文献
17.
Gatta T Campanella L Coluzza C Mambro V Postorino P Tomassetti M Visco G 《Chemistry Central journal》2012,6(Z2):S2
Background and methods
Several standard powdered black pigments were characterized by means of thermogravimetry TG-DTG and allied techniques. These pigments were used to make standard plaster frescoes at this purpose prepared. The latter ones were subjected to Raman and reflectance analysis. The results obtained, together with TG data, were chemometrically processed and used to identify an analogous standard fresco fabricated by an unknown commercial black pigment, obtaining excellent results.Results
The same colorimetric and reflectometric techniques, coupled with suitable chemometric techniques, were then successfully used to identify the type of black pigment present in an ancient roman fresco of the Imperial Age (30 B.C.).Conclusion
TG-DTG resulted useful techniques to autenticate powdered black pigments.Colorimetry and Raman, but also the only colorimetry, were useful to identify an ancient black pigment in situ.18.
Michael T. Marty Hao Zhang Weidong Cui Michael L. Gross Stephen G. Sligar 《Journal of the American Society for Mass Spectrometry》2014,25(2):269-277
Nanodiscs are a promising system for studying gas-phase and solution complexes of membrane proteins and lipids. We previously demonstrated that native electrospray ionization allows mass spectral analysis of intact Nanodisc complexes at single lipid resolution. This report details an improved theoretical framework for interpreting and deconvoluting native mass spectra of Nanodisc lipoprotein complexes. In addition to the intrinsic lipid count and charge distributions, Nanodisc mass spectra are significantly shaped by constructive overlap of adjacent charge states at integer multiples of the lipid mass. We describe the mathematical basis for this effect and develop a probability-based algorithm to deconvolute the underlying mass and charge distributions. The probability-based deconvolution algorithm is applied to a series of dimyristoylphosphatidylcholine Nanodisc native mass spectra and used to provide a quantitative picture of the lipid loss in gas-phase fragmentation. Figure
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19.
Kennedy F. Rubert-Nason Liza M. Holeski John J. Couture Adam Gusse Daniel J. Undersander Richard L. Lindroth 《Analytical and bioanalytical chemistry》2013,405(4):1333-1344
Poplar (Populus) and birch (Betula) species are widely distributed throughout the northern hemisphere, where they are foundation species in forest ecosystems and serve as important sources of pulpwood. The ecology of these species is strongly linked to their foliar chemistry, creating demand for a rapid, inexpensive method to analyze phytochemistry. Our study demonstrates the feasibility of using near-infrared reflectance spectroscopy (NIRS) as an inexpensive, high-throughput tool for determining primary (e.g., nitrogen, sugars, starch) and secondary (e.g., tannins, phenolic glycosides) foliar chemistry of Populus and Betula species, and identifies conditions necessary for obtaining reliable quantitative data. We developed calibrations with high predictive power (residual predictive deviations?≤?7.4) by relating phytochemical concentrations determined with classical analytical methods (e.g., spectrophotometric assays, liquid chromatography) to NIR spectra, using modified partial least squares regression. We determine that NIRS, although less sensitive and precise than classical methods for some compounds, provides useful predictions in a much faster, less expensive manner than do classical methods. Graphical abstract
Near-infrared reflectance spectroscopy with calibrations based on modified partial least squares regression can provide quantitative measurements of foliar nitrogen, carbohydrate, tannin, and phenolic glycoside content in poplar and birch 相似文献
20.
A biosensor for hydrogen peroxide was constructed by immobilizing horseradish peroxidase on chitosan-wrapped NiFe2O4 nanoparticles on a glassy carbon electrode (GCE). The electron mediator carboxyferrocene was also immobilized on the surface of the GCE. UV?Cvis spectra, Fourier transform IR spectra, scanning electron microscopy, and electrochemical impedance spectra were acquired to characterize the biosensor. The experimental conditions were studied and optimized. The biosensor responds linearly to H2O2 in the range from 1.0?×?10?5 to 2.0?×?10?3?M and with a detection limit of 2.0?×?10?6?M (at S/N?=?3). Figure
A biosensor for hydrogen peroxide was constructed by immobilizing horseradish peroxidase on chitosan-wrapped NiFe2O4 nanoparticles on a glassy carbon electrode. 相似文献