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https://www.readbyqxmd.com/read/28852816/ir-maldesi-method-optimization-based-on-time-resolved-measurement-of-ion-yields
#1
Måns Ekelöf, David C Muddiman
In the field of mass spectrometry imaging, typical experiments involve ionization directly from complex samples with no pre-ionization separation, relying on high resolving power mass analyzers to separate ions of interest. When an ion trapping step is involved in the analysis, the dynamic range of the analysis may be limited by the capacity of the ion trap, which is easily exceeded. To minimize collection of undesired ambient species while maximizing collection of analyte signal, accurate timing between ion generation and collection is a requirement...
August 29, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28841760/direct-screening-of-enzyme-activity-using-infrared-matrix-assisted-laser-desorption-electrospray-ionization-ir-maldesi
#2
Milad Nazari, Måns Ekelöf, Sitora Khodjaniyazova, Nathaniel L Elsen, Jon D Williams, David C Muddiman
RATIONALE: High-throughput screening (HTS) is a critical step in the drug discovery process. However, most mass spectrometry-based HTS methods require sample cleanup steps prior to analysis. In this work we present the utility of infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) for monitoring an enzymatic reaction directly from a biological buffer system with no sample cleanup and at high throughput. METHODS: IR-MALDESI was used to directly analyze reaction mixtures from a well plate at different time points after reaction initiation...
August 25, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28819677/direct-analysis-of-terpenes-from-biological-buffer-systems-using-sesi-and-ir-maldesi
#3
Milad Nazari, Alexandra A Malico, Måns Ekelöf, Sean Lund, Gavin J Williams, David C Muddiman
Terpenes are the largest class of natural products with a wide range of applications including use as pharmaceuticals, fragrances, flavorings, and agricultural products. Terpenes are biosynthesized by the condensation of a variable number of isoprene units resulting in linear polyisoprene diphosphate units, which can then be cyclized by terpene synthases into a range of complex structures. While these cyclic structures have immense diversity and potential in different applications, their direct analysis in biological buffer systems requires intensive sample preparation steps such as salt cleanup, extraction with organic solvents, and chromatographic separations...
August 17, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28721672/ir-maldesi-mass-spectrometry-imaging-at-50-micron-spatial-resolution
#4
Mark T Bokhart, Jeffrey Manni, Kenneth P Garrard, Måns Ekelöf, Milad Nazari, David C Muddiman
High spatial resolution in mass spectrometry imaging (MSI) is crucial to understanding the biology dictated by molecular distributions in complex tissue systems. Here, we present MSI using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) at 50 μm resolution. An adjustable iris, beam expander, and an aspherical focusing lens were used to reduce tissue ablation diameters for MSI at high resolution. The laser beam caustic was modeled using laser ablation paper to calculate relevant laser beam characteristics...
July 18, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28252942/ambient-characterization-of-synthetic-fibers-by-laser-ablation-electrospray-ionization-mass-spectrometry
#5
Fred A M G van Geenen, Maurice C R Franssen, Anton H M Schotman, Han Zuilhof, Michel W F Nielen
Direct analysis of synthetic fibers under ambient conditions is highly desired to identify the polymer, the finishes applied and irregularities that may compromise its performance and value. In this paper, laser ablation electrospray ionization ion mobility time-of-flight mass spectrometry (LAESI-IMS-TOF-MS) was used for the analysis of synthetic polymers and fibers. The key to this analysis was the absorption of laser light by aliphatic and aromatic nitrogen functionalities in the polymers. Analysis of polyamide (PA) 6, 46, 66, and 12 pellets and PA 6, 66, polyaramid and M5 fibers yielded characteristic fragment ions without any sample pretreatment, enabling their unambiguous identification...
April 4, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/27848143/direct-analysis-of-triterpenes-from-high-salt-fermented-cucumbers-using-infrared-matrix-assisted-laser-desorption-electrospray-ionization-ir-maldesi
#6
Måns Ekelöf, Erin K McMurtrie, Milad Nazari, Suzanne D Johanningsmeier, David C Muddiman
High-salt samples present a challenge to mass spectrometry (MS) analysis, particularly when electrospray ionization (ESI) is used, requiring extensive sample preparation steps such as desalting, extraction, and purification. In this study, infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) coupled to a Q Exactive Plus mass spectrometer was used to directly analyze 50-μm thick slices of cucumber fermented and stored in 1 M sodium chloride brine. From the several hundred unique substances observed, three triterpenoid lipids produced by cucumbers, β-sitosterol, stigmasterol, and lupeol, were putatively identified based on exact mass and selected for structural analysis...
November 15, 2016: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/27484166/infrared-matrix-assisted-laser-desorption-electrospray-ionization-mass-spectrometry-imaging-analysis-of-biospecimens
#7
M T Bokhart, D C Muddiman
Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) is a technique well suited for analysis of biological specimens. This tutorial review focuses on recent advancements and applications of IR-MALDESI MSI to better understand key biological questions. Through optimization of user-defined source parameters, comprehensive and quantitative MSI data can be obtained for a variety of analytes. The effect of an ice matrix layer is well defined in the context of desorption dynamics and resulting ion abundance...
September 21, 2016: Analyst
https://www.readbyqxmd.com/read/27077488/whole-body-mass-spectrometry-imaging-by-infrared-matrix-assisted-laser-desorption-electrospray-ionization-ir-maldesi
#8
Milad Nazari, Mark T Bokhart, David C Muddiman
Ambient ionization sources for mass spectrometry (MS) have been the subject of much interest in the past decade. Matrix-assisted laser desorption electrospray ionization (MALDESI) is an example of such methods, where features of matrix-assisted laser desorption/ionization (MALDI) (e.g., pulsed nature of desorption) and electrospray ionization (ESI) (e.g., soft-ionization) are combined. One of the major advantages of MALDESI is its inherent versatility. In MALDESI experiments, an ultraviolet (UV) or infrared (IR) laser can be used to resonantly excite an endogenous or exogenous matrix...
March 24, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/26942738/transomic-analysis-of-forebrain-sections-in-sp2-conditional-knockout-embryonic-mice-using-ir-maldesi-imaging-of-lipids-and-lc-ms-ms-label-free-proteomics
#9
Philip Loziuk, Florian Meier, Caroline Johnson, H Troy Ghashghaei, David C Muddiman
Quantitative methods for detection of biological molecules are needed more than ever before in the emerging age of "omics" and "big data." Here, we provide an integrated approach for systematic analysis of the "lipidome" in tissue. To test our approach in a biological context, we utilized brain tissue selectively deficient for the transcription factor Specificity Protein 2 (Sp2). Conditional deletion of Sp2 in the mouse cerebral cortex results in developmental deficiencies including disruption of lipid metabolism...
May 2016: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/26688545/analysis-of-antiretrovirals-in-single-hair-strands-for-evaluation-of-drug-adherence-with-infrared-matrix-assisted-laser-desorption-electrospray-ionization-mass-spectrometry-imaging
#10
Elias P Rosen, Corbin G Thompson, Mark T Bokhart, Heather M A Prince, Craig Sykes, David C Muddiman, Angela D M Kashuba
Adherence to a drug regimen can be a strong predictor of health outcomes, and validated measures of adherence are necessary at all stages of therapy from drug development to prescription. Many of the existing metrics of drug adherence (e.g., self-report, pill counts, blood monitoring) have limitations, and analysis of hair strands has recently emerged as an objective alternative. Traditional methods of hair analysis based on LC-MS/MS (segmenting strands at ≥1 cm length) are not capable of preserving a temporal record of drug intake at higher resolution than approximately 1 month...
January 19, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/26056514/assessing-drug-and-metabolite-detection-in-liver-tissue-by-uv-maldi-and-ir-maldesi-mass-spectrometry-imaging-coupled-to-ft-icr-ms
#11
Jeremy A Barry, M Reid Groseclose, Guillaume Robichaud, Stephen Castellino, David C Muddiman
Determining the distribution of a drug and its metabolites within tissue is a key facet of evaluating drug candidates. Drug distribution can have a significant implication in appraising drug efficacy and potential toxicity. The specificity and sensitivity of mass spectrometry imaging (MSI) make it a perfect complement to the analysis of drug distributions in tissue. The detection of lapatinib as well as several of its metabolites in liver tissue was determined by MSI using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) coupled to high resolving power Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers...
February 1, 2015: International Journal of Mass Spectrometry
https://www.readbyqxmd.com/read/25840812/influence-of-desorption-conditions-on-analyte-sensitivity-and-internal-energy-in-discrete-tissue-or-whole-body-imaging-by-ir-maldesi
#12
Elias P Rosen, Mark T Bokhart, H Troy Ghashghaei, David C Muddiman
Analyte signal in a laser desorption/postionization scheme such as infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is strongly coupled to the degree of overlap between the desorbed plume of neutral material from a sample and an orthogonal electrospray. In this work, we systematically examine the effect of desorption conditions on IR-MALDESI response to pharmaceutical drugs and endogenous lipids in biological tissue using a design of experiments approach. Optimized desorption conditions have then been used to conduct an untargeted lipidomic analysis of whole body sagittal sections of neonate mouse...
June 2015: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/25486925/cellular-level-mass-spectrometry-imaging-using-infrared-matrix-assisted-laser-desorption-electrospray-ionization-ir-maldesi-by-oversampling
#13
Milad Nazari, David C Muddiman
Mass spectrometry imaging (MSI) allows for the direct and simultaneous analysis of the spatial distribution of molecular species from sample surfaces such as tissue sections. One of the goals of MSI is monitoring the distribution of compounds at the cellular resolution in order to gain insights about the biology that occurs at this spatial level. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) imaging of cervical tissue sections was performed using a spot-to-spot distance of 10 μm by utilizing the method of oversampling, where the target plate is moved by a distance that is less than the desorption radius of the laser...
March 2015: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/25318460/quantitative-mass-spectrometry-imaging-of-emtricitabine-in-cervical-tissue-model-using-infrared-matrix-assisted-laser-desorption-electrospray-ionization
#14
Mark T Bokhart, Elias Rosen, Corbin Thompson, Craig Sykes, Angela D M Kashuba, David C Muddiman
A quantitative mass spectrometry imaging (QMSI) technique using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is demonstrated for the antiretroviral (ARV) drug emtricitabine in incubated human cervical tissue. Method development of the QMSI technique leads to a gain in sensitivity and removal of interferences for several ARV drugs. Analyte response was significantly improved by a detailed evaluation of several cationization agents. Increased sensitivity and removal of an isobaric interference was demonstrated with sodium chloride in the electrospray solvent...
March 2015: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/25303475/silver-dopants-for-targeted-and-untargeted-direct-analysis-of-unsaturated-lipids-via-infrared-matrix-assisted-laser-desorption-electrospray-ionization-ir-maldesi
#15
Florian Meier, Kenneth P Garrard, David C Muddiman
RATIONALE: Unsaturated lipids play a crucial role in cellular processes as signaling factors, membrane building blocks or energy storage molecules. However, adequate mass spectrometry imaging of this diverse group of molecules remains challenging. In this study we implemented silver cationization for direct analysis by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) to enhance the ion abundances for olefinic lipids and facilitate peak assignment. METHODS: Trace amounts of silver nitrate were doped into the electrospray solvent of an IR-MALDESI imaging source coupled to an Orbitrap mass analyzer...
November 30, 2014: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/25081013/analysis-of-trace-fibers-by-ir-maldesi-imaging-coupled-with-high-resolving-power-ms
#16
Kristin H Cochran, Jeremy A Barry, Guillaume Robichaud, David C Muddiman
Trace evidence is a significant portion of forensic cases. Textile fibers are a common form of trace evidence that are gaining importance in criminal cases. Currently, qualitative techniques that do not yield structural information are primarily used for fiber analysis, but mass spectrometry is gaining an increasing role in this field. Mass spectrometry yields more quantitative structural information about the dye and polymer that can be used for more conclusive comparisons. Matrix-assisted laser desorption electrospray ionization (MALDESI) is a hybrid ambient ionization source being investigated for use in mass spectrometric fiber analysis...
January 2015: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/24744212/mapping-antiretroviral-drugs-in-tissue-by-ir-maldesi-msi-coupled-to-the-q-exactive-and-comparison-with-lc-ms-ms-srm-assay
#17
Jeremy A Barry, Guillaume Robichaud, Mark T Bokhart, Corbin Thompson, Craig Sykes, Angela D M Kashuba, David C Muddiman
This work describes the coupling of the IR-MALDESI imaging source with the Q Exactive mass spectrometer. IR-MALDESI MSI was used to elucidate the spatial distribution of several HIV drugs in cervical tissues that had been incubated in either a low or high concentration. Serial sections of those analyzed by IR-MALDESI MSI were homogenized and analyzed by LC-MS/MS to quantify the amount of each drug present in the tissue. By comparing the two techniques, an agreement between the average intensities from the imaging experiment and the absolute quantities for each drug was observed...
December 2014: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/24385399/ir-maldesi-mass-spectrometry-imaging-of-biological-tissue-sections-using-ice-as-a-matrix
#18
Guillaume Robichaud, Jeremy A Barry, David C Muddiman
Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging of biological tissue sections using a layer of deposited ice as an energy-absorbing matrix was investigated. Dynamics of plume ablation were first explored using a nanosecond exposure shadowgraphy system designed to simultaneously collect pictures of the plume with a camera and collect the Fourier transform ion cyclotron resonance FT-ICR mass spectrum corresponding to that same ablation event. Ablation of fresh tissue analyzed with and without using ice as a matrix were compared using this technique...
March 2014: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/23715870/mass-recalibration-of-ft-icr-mass-spectrometry-imaging-data-using-the-average-frequency-shift-of-ambient-ions
#19
Jeremy A Barry, Guillaume Robichaud, David C Muddiman
Achieving and maintaining high mass measurement accuracy (MMA) throughout a mass spectrometry imaging (MSI) experiment is vital to the identification of the observed ions. However, when using FTMS instruments, fluctuations in the total ion abundance at each pixel due to inherent biological variation in the tissue section can introduce space charge effects that systematically shift the observed mass. Herein we apply a recalibration based on the observed cyclotron frequency shift of ions found in the ambient laboratory environment, polydimethylcyclosiloxanes (PDMS)...
July 2013: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/23237031/direct-analysis-of-textile-fabrics-and-dyes-using-infrared-matrix-assisted-laser-desorption-electrospray-ionization-mass-spectrometry
#20
Kristin H Cochran, Jeremy A Barry, David C Muddiman, David Hinks
The forensic analysis of textile fibers uses a variety of techniques from microscopy to spectroscopy. One such technique that is often used to identify the dye(s) within the fiber is mass spectrometry (MS). In the traditional MS method, the dye must be extracted from the fabric and the dye components are separated by chromatography prior to mass spectrometric analysis. Direct analysis of the dye from the fabric allows the omission of the lengthy sample preparation involved in extraction, thereby significantly reducing the overall analysis time...
January 15, 2013: Analytical Chemistry
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