Kermit K Murray

• Ph.D.
• Professor at Louisiana State University

Atomic force microscope (AFM) tip-enhanced laser ablation was used to transfer molecules from thin films to a suspended silver wire for off-line mass spectrometry using laser desorption ionization (LDI) and matrix-assisted laser desorption ionization (MALDI). An AFM with a 30 nm radius gold-coated silicon tip was used to image the sample and to hol...

RATIONALE: Detection of hydrophobic peptides remains a major obstacle for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This stems from the fact that most matrices for MALDI are hydrophilic and therefore have low affinities for hydrophobic peptides. Herein, 1-aminopyrene (AP) and AP-derived group of uniform materials bas...

The concentration and size distribution of particles ablated from the infrared matrix-assisted laser desorption/ionization matrix compounds succinic acid (butanedioic acid), α-cyano-4-hydroxycinnamic acid, and glycerol were measured using an aerodynamic particle sizer combined with a scanning mobility particle sizer. The two sizing instruments toge...

Ambient laser ablation with mass spectrometric detection is a powerful method for direct analysis of biological samples in their native environment. Capillary electrophoresis (CE) can separate complex mixtures of biological molecules prior to mass spectrometry (MS) analysis and an ambient sampling interface for CE/MS will allow the detection of min...

Sampling thin tissue sections with cellular precision can be accomplished using laser ablation microsampling for mass spectrometry analysis. In this work, the use of a pulsed mid-infrared (IR) laser for selecting small regions of interest (ROI) in tissue sections for offline liquid chromatography-tandem mass spectrometry (LC-MS/MS) is described. Th...

The dynamics of infrared laser ablation at atmospheric pressure was studied employing continuous visible laser light scattering in the expanding plume. A pulsed infrared optical parametric oscillator at 2940 nm wavelength and 5 ns pulse width was used to irradiate samples comprising liquid glycerol or 50 µm thick sections of rat liver tissue. The s...

The term resolution is one of the most important in mass spectrometry because it describes the ability to separate peaks in mass spectra. The term resolving power is often used to describe the ability of a mass spectrometer to resolve adjacent peaks in a mass spectrum and is often used interchangeably with resolution. The separation of peaks for si...

Infrared laser ablation sample transfer (LAST) was used to collect samples from solid surfaces for mass spectrometry under native spray conditions. Native mass spectrometry was utilized to probe the charge states and collision-induced unfolding (CIU) characteristics of bovine serum albumin (BSA), bovine hemoglobin (BHb), and jack-bean concanavalin...

Matrix-assisted laser desorption and ionization mass spectrometry (MALDI-MS) is a fast, reliable, and accurate tool to guarantee food control in terms of pesticide distribution and microbiological contamination. In this chapter, we describe an interesting protocol to determine the distribution of the fungicide imazalil in apples using MALDI-MS whic...

Infrared (IR) laser ablation was used to remove localized tissue regions from which proteins were extracted and processed with a low volume sample preparation workflow for bottom-up proteomics by liquid chromatography tandem mass spectrometry (LC-MS/MS). A polytetrafluoroethylene (PTFE) coated glass slide with 2 mm diameter microwells was used to c...

A Schwarzschild reflective objective with a numerical aperture of 0.3 and working distance of 10 cm was used for laser ablation sampling of tissue for off-line mass spectrometry. The objective focused the laser to a diameter of 5 μm and produced 10 μm ablation spots on thin ink films and tissue sections. Rat brain tissue sections 50 μm thick were a...

Deep-ultraviolet laser ablation with a pulsed 193 nm ArF excimer laser was used to remove localized regions from tissue sections from which proteins were extracted for spatially resolved proteomic analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS). The ability to capture intact proteins by ablation at 193 nm wavelength was verifi...

Stem cell-based therapies carry significant promise for treating human diseases. However, clinical translation of stem cell transplants for effective treatment requires precise non-destructive evaluation of the purity of stem cells with high sensitivity (<0.001% of the number of cells). Here, a novel methodology using hyperspectral imaging (HSI) co...

Heterogeneity in the distribution of nutrients and oxygen gradients during biofilm growth gives rise to changes in phenotype. There has been long term interest in identifying spatial differences during biofilm development including clues that identify chemical heterogeneity. Laser ablation sample transfer (LAST) allows site-specific sampling combin...

Matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry was introduced over 30 years ago, and it now plays a key role in several areas, including the characterization of microorganisms and tissue imaging. Lasers are, of course, a central component in MALDI mass spectrometers, but in commercial systems, the type of laser is determined...

Heterogeneity in the distribution of nutrients and O 2 gradients during biofilm growth gives rise to changes in phenotype. There has been long term interest in identifying spatial differences during biofilm development including clues that identify chemical heterogeneity. Laser ablation sample transfer (LAST) allows site-specific sampling combined...

Laser desorption (LD) and laser ablation (LA) have been applied to the mass spectrometry (MS) analysis of a wide variety of sample types and can be classified based on whether they provide atomic or molecular information. This chapter discusses advantages and disadvantages of the various LD/LA‐MS methods. Laser desorption ionization mass spectromet...

Laser desorption ionization (LDI) of atomic, molecular, cluster, or particulate species are central methods for transferring an analyte from the condensed phase to the gas phase for subsequent mass spectrometric analysis. This chapter provides a basic introduction to the fundamental chemistry and physics of LDI including the most important experime...

The term quasimolecular ion has been used to describe ions comprising a molecule and weakly bound positive or negative ion or an ion formed by the loss of a proton from a molecule. This term was used in mass spectrometry from the late 1960s after the development of chemical ionization but has been deprecated in recent terms recommendations due to w...

Malnutrition is an increasing threat to honey bees that can be mitigated by feeding artificial pollen substitute diets; however, little is known about the molecular mechanisms underlying their impact on bee health. Here, we examined proteomic responses to natural and artificial diets in the honey bee fat body, a tissue with central nutrient storage...

Post-traumatic stress disorder (PTSD) is a widespread psychiatric injury that develops serious life-threatening symptoms like substance abuse, severe depression, cognitive impairments, and persistent anxiety. However, the mechanisms of post-traumatic stress injury in brain are poorly understood due to the lack of practical methods to reveal biochem...

Matrix‐assisted laser desorption ionization (MALDI) was introduced 35 years ago and has advanced from a general method for producing intact ions from large biomolecules to wide use in applications ranging from bacteria identification to tissue imaging. MALDI was enabled by the development of high energy pulsed lasers that create ions from solid sam...

a>Post-traumatic stress disorder (PTSD) is a widespread psychiatric injury that develops serious life-threatening symptoms like substance abuse, severe depression, cognitive impairments and persistent anxiety. However, the mechanisms of post-traumatic stress injury in brain is poorly understood due to the lack of practical methods to reveal biochem...

Stem cell-based therapies carry significant promise for treating human diseases. However, clinical translation of stem cell transplants for effective therapy requires precise non-destructive evaluation of the purity of stem cells with high sensitivity (< 0.001% of the number of cells). Here, we report a novel methodology using hyperspectral imaging...

The electrification of crystalline deposits of organic compounds under high vacuum was measured and quantified. A group of compounds that produce multiply charged ions by matrix assisted ionization were deposited on a metal plate and the current was amplified and recorded; the total charge was obtained by integration of the current. Signals of seve...

The wavelength dependence of atomic force microscope apertureless tip-enhanced laser ablation was studied using a series of organic dyes to assess the effect of surface optical absorption. An optical parametric oscillator laser with a tunable wavelength range of 410-2100 nm was used to irradiate a gold-coated atomic force microscope tip which was h...

A multi‐modal workflow for mass spectrometry imaging was developed that combines MALDI imaging with protein identification and quantification by liquid chromatography tandem mass spectrometry (LC‐MS/MS). Thin tissue sections were analyzed by MALDI imaging and the regions of interest (ROI) were identified using a smoothing and edge detection procedu...

Photooxidation of peptides and proteins by pulsed ultraviolet laser irradiation of an electrospray in the ion source of a mass spectrometer was demonstrated. A 193-nm excimer laser at 1.5-mJ pulse energy was focused with a cylindrical lens at the exit of a nanoelectrospray capillary and ions were sampled into a quadrupole time-of-flight mass spectr...

Photooxidation of peptides and proteins by pulsed ultraviolet laser irradiation of an electrospray in the ion source of a mass spectrometer was demonstrated. A 193-nm excimer laser at 1.5-mJ pulse energy was focused with a cylindrical lens at the exit of a nanoelectrospray capillary and ions were sampled into a quadrupole time-of-flight mass spectr...

Tip-enhanced laser ablation was used to extract DNA plasmid for polymerase chain reaction (PCR) amplification. A 532 nm nanosecond laser was directed onto a gold coated atomic force microscopy (AFM) tip 10 nm above a sample surface to ablate a 7.1 kbp green fluorescent protein (GFP) plasmid DNA sample on a glass coverslip. The ablated material was...

A combination of matrix-assisted laser desorption ionization (MALDI) imaging and infrared (IR) laser ablation sampling with off-line electrospray ionization mass spectrometry (ESI-MS) was used to determine the distribution of the fungicide imazalil in apples. MALDI images were used to determine the penetration depth of imazalil up to 7 days after i...

Rationale A two‐component matrix of 2‐nitrophloroglucinol (2‐NPG) and silica nanoparticles was used for matrix‐assisted laser desorption ionization mass spectrometry imaging of high charge state biomolecules in tissue. Potential applications include increased effective mass range and efficiency of fragmentation. Methods A mixture of 2‐NPG matrix a...

(Free access until 27 May 2019 at https://authors.elsevier.com/a/1YrzBlYfXcR8) RNA was obtained from discrete locations of frozen rat brain tissue sections through infrared (IR) laser ablation using a 3-μm wavelength in transmission geometry. The ablated plume was captured in a microcentrifuge tube containing RNAse-free buffer and processed using a...

A 193 nm wavelength deep ultraviolet laser was used for ambient laser ablation electrospray ionization mass spectrometry of biological samples. A pulsed ArF excimer laser was used to ablate solid samples and the resulting plume of desorbed material merged with charged electrospray droplets to form ions that were detected with a quadrupole time‐of‐f...

We have developed a new actuation method for matrix-assisted ionization with good temporal and spatial resolution using piezoelectric cantilever. A strike from the piezoelectric bimorph cantilever on a thin metal foil was used to remove materials deposited on the opposite side facing the mass spectrometer inlet. Highly charged ions of peptides and...

Infrared laser ablation microsampling was used with data-dependent acquisition (DDA) and ion mobility-enhanced data-independent acquisition (HDMSE) for mass spectrometry based bottom-up proteomics analysis of rat brain tissue. Results from HDMSE and DDA analyses of the 12 laser ablation sampled tissue sections showed that HDMSE consistently identif...

Perform IR laser ablation capture on FFPE and fresh-frozen sections from the same rat brain organ followed by protein digestion and liquid chromatography (LC) for high definition MSE (HDMSE) analysis to uncover the differences between the two conservation techniques

Tissue sample preparation method for simultaneous isolation of lipid and protein fractions for untargeted MS analyses

Infrared (IR) laser ablation at 3 μm wavelength was used to extract enzymes from tissue and quantitatively determine their activity. Experiments were conducted with trypsin, which was ablated, captured and then used to digest bovine serum albumin (BSA). BSA digests were evaluated using matrix-assisted laser desorption ionization (MALDI) mass spectr...

High resolving power ion mobility (IM) allows for accurate characterization of complex mixtures in high-throughput IM mass spectrometry (IM-MS) experiments. We previously demonstrated that pure component IM-MS data can be extracted from IM unresolved post-IM/collision-induced dissociation (CID) MS data using an Automated Ion Mobility Deconvolution...

The role of laser wavelength in atomic force microscopy (AFM) tip-enhanced laser ablation was studied using an apertureless tip and a nanosecond pulsed laser. An optical parametric oscillator (OPO) laser wavelength tunable from 410 to 2400 nm was used to irradiate a gold-coated silicon AFM probe held 15 nm above the surface of an anthracene film. T...

Our research focuses on applying ambient laser ablation sampling methods to formalin fixed paraffin embedded (FFPE) tissue analysis via mass spectrometry (MS). Efficient sampling of proteins in FFPE tissue can broaden the applicability of MS to archival specimens. An IR laser is used to ablate biological material and capture it in different fashion...

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonst...

Infrared (IR) laser ablation was used to remove material from tissue sections mounted on microscope slides, with subsequent capture in a solvent-containing microcentrifuge tube. Experiments conducted with a 3200-bp double-stranded plasmid DNA template demonstrated IR-laser ablation transfer of intact DNA. The transfer efficiency and the molecular i...

We have developed a new ionization approach for matrix-assisted ionization with high temporal resolution using an electrically actuated pulsed valve. Matrix and analyte samples are deposited on a thin metal foil and placed at the inlet of an ambient ionization mass spectrometer. When the pulsed valve is actuated, a short puff of high pressure gas i...

A systematic method for evaluation of MALDI profiling and imaging was developed and applied to the use of three surfactants, sodium dodecyl sulfate (SDS), Triton X-100, and Tween 20, on rat brain tissue. For profiling studies, mass spectra were acquired from regular arrays of spots with manually deposited surfactant and matrix. The studies recorded...

MSI (MSI) was introduced more than five decades ago with secondary ion mass spectrometry (SIMS) and a decade later with laser desorption/ionization (LDI) mass spectrometry (MS). Large biomolecule imaging by matrix-assisted laser desorption/ionization (MALDI) was developed in the 1990s and ambient laser MS a decade ago. Although SIMS has been capabl...

Rationale: Ambient mass spectrometry can detect small molecules directly, but complex mixtures can be a challenge. We have developed a method that incorporates small molecule separation based on laser desorption with capture on a solid-phase microextraction (SPME) fiber for injection into a gas chromatography/mass spectrometry (GC/MS) system. Met...

We have developed a mid-infrared laser ablation sampling technique for nano-flow liquid chromatography coupled with tandem mass spectrometry proteomic profiling of discrete regions from biological samples. Laser ablation performed in transmission geometry was used to transfer material from 50-mu m thick tissue sections mounted on a glass microscope...

The concentration and size distribution were measured for particles ablated from tissue sections using an infrared optical parametric oscillator laser system. A scanning mobility particle sizer and light scattering particle sizer were used in parallel to realize a particle sizing range from 10 nm to 20 μm. Tissue sections from rat brain and lung ra...

Infrared laser ablation sample transfer (IR-LAST) is a novel ambient sampling technique for mass spectrometry. In this technique, a pulsed mid-IR laser is used to ablate materials that are collected for mass spectrometry analysis; the material can be a solid sample or deposited on a sample target. After collection, the sample can be further separat...

We have developed a laser ablation sampling technique for matrix-assisted laser desorption ionization (MALDI) mass spectrometry and tandem mass spectrometry (MS/MS) analyses of in-situ digested tissue proteins. Infrared laser ablation was used to remove biomolecules from tissue sections for collection by vacuum capture and analysis by MALDI. Ablati...

Mass spectrometry is one of the primary analysis techniques for biological analysis but there are technological barriers in sampling scale that must be overcome for it to be used to its full potential on the size scale of single cells. Current mass spectrometry imaging methods are limited in spatial resolution when analyzing large biomolecules. The...

The goal of this work is to develop a method for ambient laser ablation sampling for mass spectrometry and other bioanalytical techniques. An optical parametric oscillator laser system operating in the 3 µm wavelength region of the mid-infrared is used to ablate material from a cell or tissue sample that is drawn into a capillary by means of suctio...

Ionic liquids (ILs) are rapidly emerging as important coating materials for highly sensitive chemical sensing devices. In this regard, we have previously demonstrated that a quartz crystal microbalance (QCM) coated with a binary mixture of an IL and cellulose acetate can be employed for detection and molecular weight estimation of organic vapors (J...

Introduction A project to update standard definitions of terms relating to mass spectrometry was initiated at the 42nd IUPAC General Assembly in Ottawa, Canada, in August 2003. The current Task Group (the authors of this presentation) was assembled in 2004 and a glossary of mass spectrometry terms and definitions was assembled with extensive input...

Many biochemical analyses of biological systems are performed on groups of cells based on the assumption that the cells are sufficiently similar that an ensemble average from the cell group will yield a useful result. However, this approach can obscure the underlying heterogeneity of the individual cells and masks import and differences in gene exp...

Particles were ablated from laser desorption and inlet ionization matrix thin films with a UV laser in reflection and transmission geometries. Particle size distributions were measured with a combined scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) system that measured particles in the size range from 10 nm to 20 μm. Th...

This document contains recommendations for terminology in mass spectrometry. Development of standard terms dates back to 1974 when the IUPAC Commission on Analytical Nomenclature issued recommendations on mass spectrometry terms and definitions. In 1978, the IUPAC Commission on Molecular Structure and Spectroscopy updated and extended the recommend...

Mass spectrometry-based proteomics can be used to investigate the properties of alligator leukocytes and better understand the alligator innate immune system. Proteomics is critical to understanding complex biological systems through the elucidation of protein expression, function, modifications, and interactions. Separation techniques, including l...

We have demonstrated an on-line laser ablation sampling system and coupling of the system to liquid chromatography (LC) using an infrared (IR) laser to ablate and transfer materials into a flowing solvent stream. With this approach, samples are deposited on a microscope slide mounted on a translation stage and ablated in transmission geometry using...

Laser ablation is widely used in conjunction with ambient ionization techniques, and a fundamental understanding of the mechanism of material removal is important to its optimal use in mass spectrometry. Finite element analysis simulates the laser material interaction on larger time and distance scales than atomistic approaches. Here, a two-dimensi...

An infrared laser was used to ablate material from tissue sections under ambient conditions for direct collection on a matrix assisted laser desorption ionization (MALDI) target. A 10 μm thick tissue sample was placed on a microscope slide and was mounted tissue-side down between 70 and 450 μm from a second microscope slide. The two slides were mou...

Mass spectrometry in conjunction with de novo sequencing was used to determine the amino acid sequence of a 35kDa lectin protein isolated from the serum of the American alligator that exhibits binding to mannose. The protein N-terminal sequence was determined using Edman degradation and enzymatic digestion with different proteases was used to gener...

Mass spectrometry (MS) analysis, after enzymatic or chemical deglycosylation, requires preparatory steps to remove salts and buffers. In this work, the glycosylated protein fetuin and a lectin protein isolated from the serum of Alligator mississippiensis were used to evaluate methods for desalting samples after an enzymatic or chemical deglycosylat...

Post-translational modifications (PTM) of proteins play essential roles in cellular physiology and disease. The identification of protein substrates and detection of modification site helps understand PTM-mediated regulation in essential biological pathways and functions in various diseases. However, PTM proteins are typically present only at trace...

The ablated particle count and size distribution of four solid matrix materials commonly used for matrix-assisted laser desorption ionization (MALDI) were measured with a scanning mobility particle sizer (SMPS) combined with a light scattering aerodynamic particle sizer (APS). The two particle sizing instruments allowed size measurements in the ran...

We have used an infrared laser to ablate materials under ambient conditions that were captured in solvent droplets. The droplets were either deposited on a MALDI target for off-line analysis by MALDI time-of-flight mass spectrometry or flow-injected into a nanoelectrospray source of an ion trap mass spectrometer. An infrared optical parametric osci...

Ion mobility mass spectrometry (IMMS) was combined with matrix assisted laser desorption ionization (MALDI) for the analysis of whole cell bacteria. Whole cell Bacillus subtilis ATCC 6633 and Escherichia coli strain W ATCC 9637 bacteria were prepared with a 1:2 analyte to matrix (CHCA) ratio and deposited using the dried-droplet method. Matrix-assi...

We report the development of a solid-phase proteolytic digestion and continuous deposition microfluidic chip platform for low volume fraction collection and off-line matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Tryptic peptides were formed in an on-chip bioreactor and continuously deposited onto a MALDI...

Continuous flow infrared matrix-assisted laser desorption electrospray ionization (CF IR MALDESI) mass spectrometry was demonstrated for the on-line analysis of liquid samples. Samples in aqueous solution were flowed through a 50 µm i.d. fused-silica capillary at a flow rate of 1-6 µL/min. As analyte aqueous solution flowed through the capillary, a...

This document is a glossary of terms for separations coupled to mass spectrometry. It covers gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry, and supercritical fluid chromatography/mass spectrometry and the sample introduction, ionization, and data analysis methods used with these combined techniques.

Presented here is a novel ambient ion source termed infrared laser ablation metastable-induced chemical ionization (IR-LAMICI). IR-LAMICI integrates IR laser ablation and direct analysis in real time (DART)-type metastable-induced chemical ionization for open air mass spectrometry (MS) ionization. The ion generation in the IR-LAMICI source is a two...

The dynamics of glycerol ablation at atmospheric pressure was studied using fast photography. A mid-infrared optical parametric oscillator was used to irradiate a droplet of glycerol at normal incidence. The wavelength of the infrared source was tunable and was varied between 2.7 and 3.5 microm for the studies. After an adjustable delay, an excimer...

A solid-phase trypsin microreactor was constructed and operated with electrokinetically-driven flow for the digestion of proteins and coupled off-line with MALDI-TOF MS. The bioreactor was fabricated from poly(methyl methacrylate), PMMA, by hot embossing using a mold master prepared by micro-milling. The solid-phase bioreactor consisted of a 4 cm l...

Various microfluidic devices have been developed for proteomic analyses and many of these have been designed specifically for mass spectrometry detection. In this review, we present an overview of chip fabrication, microfluidic components, and the interfacing of these devices to matrix-assisted laser desorption ionization (MALDI) mass spectrometry....

Introduction We report on the development of an automated cell culturing, digestion, and deposition microfluidic chip device for the identification of bacteria using off-line matrix-assisted laser desorption ionization (MALDI) mass spectrometry. Rapid identification of microorganisms is required for detection of environmental pathogens, pathogens...

Microfluidic devices coupled to mass spectrometers have emerged as excellent tools for solving the complex analytical challenges associated with the field of proteomics. Current proteome identification procedures are accomplished through a series of steps that require many hours of labor-intensive work. Microfluidics can play an important role in p...

Particles generated by 2.94 mu m pulsed IR laser ablation of liquid 3-nitrobenzyl alcohol were irradiated with a 351 nm UV laser 3.5 mm above and parallel to the sample target. The size and concentration of the ablated particles were measured with a light scattering particle sizer. The application of the UV laser resulted in a reduction in the aver...

We report the implementation of an infrared laser onto our previously reported matrix-assisted laser desorption electrospray ionization (MALDESI) source with ESI post-ionization yielding multiply charged peptides and proteins. Infrared (IR)-MALDESI is demonstrated for atmospheric pressure desorption and ionization of biological molecules ranging in...

The recent explosion in the use of analytical chemistry, particularly in the biological sciences, has led to a need for fast, reliable and highly sensitive tools able to handle small sample sizes. This book illustrates how microfluidics and lab-on-a-chip devices can satisfy the growing need for miniaturized and enhanced analysis. They lend themselv...

Particles were generated from glycerol that was irradiated at atmospheric pressure using a mid-infrared optical parametric oscillator at wavelengths between 2.6 and 3.8 μm. The size distribution and quantity of ejected particles with diameters larger than 300 nm were measured using an aerodynamic particle sizer. At a given fluence, the particle con...