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Topic: MALDI matrix

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	Maldi Peptide Spectra
		To interpret a MALDI spectrum de novo, all we can do is to regard each peak separately, and ask 'what peptides could have given rise to this peak?' We know that the mass of a peptide is the sum of the amino acids which comprise it, as listed in table 4.
		Given a mass read from a MALDI peak, and a protein library, it is easy to write a computer algorithm to 'walk' through the library, identifying sequences of amino acids in the library that could give rise to that mass.
		If we find our MALDI spectrum gives hits on two similar proteins, it may be hard to tell whether what we have is a genuine hit together with another similar protein, or a genuine hit together with an erroneous version of the same protein.
	www.weddslist.com /ms/maldi.html (5413 words)

	Mass Spectrometry: Remote control and collaboration
		MALDI generally produces molecular ions of the form (M+H)+ or (M-H)-; in other words, a proton (H+) is added to or taken away from the molecule to produce a molecular ion.
		MALDI is performed by mixing the analyte solution with a matrix solution, spotting a microliter of the mixture on the probe (sample plate), and allowing the solvents to evaporate.
		The matrix enhances the desorption and ionization of sample molecules when the residue is irradiated with a pulsed laser beam at 337 nm.
	www.udel.edu /topics/internet2/proj/maldi/lab.html (674 words)

	[No title]
		External ion source MALDI measurements of the molecular weight distribution of an amine terminated poly(propyleneglycol) are shown to be extremely sensitive to the ion accumulation time used, as a result of the flight time distribution of the ions from ion source to analyser cell.
		This study involves the use of matrix assisted laser/desorption ionization time-of- flight mass spectrometry (MALDI TOF MS) to investigate the effect of the addition of methyl methacrylate macromonomers as prepared by CCTP to the polymerization of perdeutero-methyl methacrylate and n-butyl methacrylate in the presence and absence of catalytic chain transfer agent.
		Matrix- assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is then used for rapid, precise, and unambiguous detection and identification of the hybridized PNA probes, Since PNA oligomers bind strongly to complementary DNA under minimal salt conditions, the use of PNA probes is compatible with MALDI-TOFMS.
	www.ch.pw.edu.pl /~maldi/maldi.doc (11530 words)

	MALDI MS
		MALDI mass spectra of melittin in CHCA comparing mass resolution obtained in the linear mode utilizing continuous ion extraction (upper) and delayed ion extraction (lower) at threshold laser irradiance.
		Many variables influence the integrity of a good, homogeneous MALDI sample and may include the concentration of the matrix and analyte, choice of matrix, analyte sample history (i.e.,exposure to strong ionic detergents, formic acid), hydrophobicity or hydrophilicity character, contaminants and compatible solubilities of matrix and analyte solutions, just to mention a few.
		MALDI fast metastable ion decay is observed for the oxidized B chain of bovine insulin (3495.94 Da) in DHB (Figure 7).
	www.abrf.org /ABRFNews/1997/June1997/jun97lennon.html (3622 words)

	[No title]
		The use of a matrix in MALDI serves as an energy mediator, in which it absorbs and distributes the energy of the laser to the molecules of interest.
		The interference is definitely not matrix originated as DIOS itself is matrix-less but it is assumed to be due to the absorption of contaminants on the silicon surface from the etching electrolyte or from the air.
		Silicon matrix cannot be vaporise to enter the gas phase, hence the reason for absence of matrix ion interference.
	www-users.york.ac.uk /~srms500/siti.org.uk/generated/silicon_dios_ms.doc.htm (1430 words)

	Matrix Assisted Laser Desorption Ionization (MALDI)
		Although the mechanism remains uncertain, it may involve absorption of UV light by the matrix followed by transfer of this energy to the peptide - which then ionizes into the gas phase as a result of the relatively large amount of energy absorbed.
		The protonated matrix molecules are generated by a series of photochemical reactions.
		The matrix performs two important functions: (1) it absorbs photon energy from the laser beam and transfers it into excitation energy of the solid system, and (2) it serves as a solvent for the analyte, so that the intermolecular forces are reduced and aggregation of the analyte molecules is held to a minimum.
	www.tau.ac.il /lifesci/units/proteomics/voyager.html (921 words)

	Matrix Science - What's New
		Proxeon's ProteinCenter and Matrix Science's Mascot software applications will be integrated to facilitate data evaluation by proteomics researchers and, in particular, to enable biologists to make better use of proteomics data.
		Matrix Science gains access to the MassLynx raw file API, improving the support for MassLynx files within Mascot Distiller.
		Matrix Science is proud to be awarded the Frost and Sullivan 2003 Technology Leadership Award in the Proteome Informatics Market for the Mascot search engine.
	www.matrixscience.com /whats_new.html (2554 words)

	Bioaerosol MALDI - Murray Mass Spectrometry Group (Site not responding. Last check: 2007-10-17)
		We have also explored on-line single aerosol particle MALDI in which the matrix is added to the particles by condensation (Jackson et al., 2004 (http://www.hubmed.org/display.cgi?issn=09514198anduids=15378715)).
		MALDI mass spectra of test bioaerosols deposited on a target pre-coated with a) sinapic acid matrix and no additional treatment, b) CHCA plus 200 µL of solvent, and c) SA plus 200 µL of 1:1 (v/v) acetonitrile/water solvent.
		The matrix-coated targets were prepared by depositing 400 µL of matrix solution on the target and allowing it to dry before the target was placed in the impactor.
	ch309c.chem.lsu.edu:16080 /wiki/index.php/Bioaerosol_MALDI (1271 words)

	D. B. Geohegan's Web Page - page 5 (Site not responding. Last check: 2007-10-17)
		MALDI is a powerful technique to accurately measure the masses of heavy molecules.
		In MALDI, a heavy biomolecule (such as a protein, or fragment of DNA) is gently laser-desorbed inside a vacuum chamber.
		In order to optimize the technique, the fraction of material which becomes ionized should be increased and the dynamics of the vaporization process must be determined in order to compensate for the initial velocities and trajectories of the ejecta down the time-of-flight mass spectrometer.
	www.ornl.gov /~odg/Page5.html (326 words)

	Recent Publications (Site not responding. Last check: 2007-10-17)
		The possible influence of intramolecular hydrogen bonding between the nucleobases and the phosphate group on the measured and calculated proton affinities and the experimentally determined protonation entropies is discussed.
		Charge-transfer ionization using non-polar matrixes in MALDI-MS is a suitable method for the characterization of a number of non-polar, thermally labile analytes.
		Conventional peptide matrixes, such as 2,5-dihydroxybenzoic acid and sinapinic acid, as well as 3-indoleacrylic acid are shown to be suitable for hydrophobic peptides.
	www.chem.lsu.edu /htdocs/people/palimbach/research/pubs.html (3228 words)

	The Influence of Laser Energy and Matrix of MALDI on the Molecular Mass Distribution of Poly(ethylene glycol)
		The Influence of Laser Energy and Matrix of MALDI on the Molecular Mass Distribution of Poly(ethylene glycol)
		We considered the effects of laser energy and matrix on the molecular mass distribution of several polymers of varying stability.
		The analysis of poly(ethylene glycol) (PEG) reveals that the matrix used in the MALDI sample preparation has an effect on the polymer mass distribution.
	www.nist.gov /sigmaxi/Posters03/Wetzel-abst.html (265 words)

	Improvement in the Detection of Low Concentration Protein Digests on a MALDI TOF/TOF Workstation by Reducing ...
		Matrix adduct-related fragment ions are observed in a peptide
		), because the matrix adduct ion abundance is
		Note the abundant ions at m/z 833.1, 855.1, and 877.0, all of which are fragments from the matrix adduct ion of m/z 1066.1 which is very close in mass to the peptide precursor ion (B).
	jbt.abrf.org /cgi/content/full/14/4/298 (1643 words)

	Hallam Biotech \| Electrospray depositor: development opportunity and analysis service (Site not responding. Last check: 2007-10-17)
		Matrix Assisted Laser Desorption Ionisation - Time of Flight (MALDI-ToF) mass spectrometry is an important tool in the analysis of many groups of compounds and especially in proteomics.
		The electrospray device is being used to analyse non-steroidal anti-inflammatory drugs from TLC plates, to assist in the structure elucidation of unknowns in the manufacture of pharmaceuticals and to develop the use of novel MALDI targets for example, tissue sections.
		MALDI matrix is electrosprayed onto the TLC strip which is than introduced to the sample port of a MALDI mass spectrometer.
	www.shu.ac.uk /research/bmrc/hallambiotech/level2/electrospray.htm (457 words)

	Press release : NanoHorizons announces Matrix-less MALDI now available - Nanovip.com (Site not responding. Last check: 2007-10-17)
		This dramatic improvement is due to the QuckMassTM target’s non-porous, thin film surface, which adsorbs and transfers the laser energy to the sample molecules.
		Accordingly, the interfering background matrix peaks that are commonly observed with MALDI MS are not present.
		Kratos Analytical employs innovative strategies in the development of MALDI MS products, including the unique patented curved field reflectron of the Axima-CFR™ for controlled seamless post source decay fragmentation of peptides, and the novel Axima-QIT™ hybrid MALDI quadrupole ion trap time-of-flight mass spectrometer, for detailed structural determination of biomolecules.
	www.nanovip.com /forums/showthread.php?p=107&mode=threaded (627 words)

	MALDI Mass
		The typical matrix for use with ultraviolet lasers is an aromatic acid with a chromophore that strongly absorbs the laser wavelength.
		It is believed that compounds with labile protons, such as carboxylic acids, are good MALDI matrices in the positive ion mode because they are easily able to protonate neutral analyte molecules in the plume.
		The MALDI method has been developed empirically and despite its widespread use, the factors that determine success or failure of MALDI experiments are not yet fully understood.
	www.sigmaaldrich.com /Brands/Fluka___Riedel_Home/Bioscience/Peptide_Analysis/MALDI_Mass.html (767 words)

	Matrix-assisted Laser Desorption/Ionisation (Site not responding. Last check: 2007-10-17)
		The use of a matrix, together with the analyte, was introduced by Tanaka and co-workers to facilitate desorption/ionisation of high-mass molecules without inducing fragmentation.
		A further requirement for a matrix is to be chemically inert in terms of reactivity with the analyte.
		Potential matrix compounds must also have low sublimation rates, as the sample must be introduced into vacuum for mass spectrometric analysis.
	www.jic.bbsrc.ac.uk /services/proteomics/maldi.htm (1049 words)

	Department of Chemistry: Graduate Colloquium (Site not responding. Last check: 2007-10-17)
		In order to remove the matrix interference signals we decided to immobilize the matrix by entrapping the matrix molecule into the sol gel network and/or by chemically binding the matrix to the surface.
		We shall report the efficiency of the MALDI experiment, including the degree of matrix interference, as a function of silica porosity and the matrix’s molar concentration used.
		These derivatives were tested as MALDI matrices as a function of laser intensity, analyte concentrations and solvent composition, in order to find the conditions for their optimal performance in MALDI.
	www.chemistry.mcmaster.ca /colloquia/0405/colloq.20041020a.html (323 words)

	Mass Spectrometry background
		MALDI is a method that allows for the ionization and transfer of a sample from a condensed phase to the gas phase in a fashion similar to FAB.
		The primary difference between MALDI and FAB is that while FAB uses an atom or ion beam and a liquid matrix, MALDI uses a solid matrix, and the ionizing beam is laser light.
		Ion formation in MALDI is accomplished by directing a pulsed beam onto a sample suspended or dissolved in a matrix.
	www.msu.edu /~gallego7/MassSpect/ms.htm (1023 words)

	Tissue Profiling by Mass Spectrometry: A Review of Methodology and Applications -- Caldwell and Caprioli 4 (4): 394 -- ...
		Matrix was deposited specifically on identified regions, and virtually identical spectra were acquired.
		Representative MALDI time-of-flight MS spectra obtained from tumor and normal lung tissue samples are shown with the molecular weights (m/z values).
		The same tissue section was spray coated with matrix, and mass spectra were acquired across the specimen.
	www.mcponline.org /cgi/content/full/4/4/394 (4003 words)

	MALDI Foils
		Conventionally, both the analyte and matrix are dissolved in solution and applied as a drop directly onto the MALDI target.
		Foils are stainless steel with a layer of matrix per-deposited onto the surface.
		The resulting track is then probed by the MALDI laser to determine the mass spectra of each of the separated components.
	www.labconnections.com /MALDIFoils.htm (294 words)

	MALDI - Innovadyne Technologies
		The Nanodrop II is an ideal benchtop solution for use in spotting MALDI plates for protein characterization and quality control of synthetic oligos, as well as analysis of laser capture microdissection (LCM) cells.
		In the application note "Improved Liquid Handling for MALDI Plate Spotting," developed in conjunction with Biosearch Technologies (Novato, CA), MALDI spotting performance for oligo QC was compared between a Nanodrop II and a BioMek FX from Beckman-Coulter under actual manufacturing use.
		It was determined that the Nanodrop generated higher quality spots (no missed or doughnut-shaped spots) and better spectra using 1/5 the volume of matrix and 1/10 the volume of oligo required by the Biomek.
	www.innovadyne.com /_MALDI.html (379 words)

	Labcyte release acoustic sample preparation technique
		The new release, which received an honorable mention in the Pittcon Editor's Awards, allows precise spatial matrix deposition and automated multi-step sample preparation protocols for MALDI (matrix-assisted laser desorption ionization) mass spectrometry imaging.
		MALDI imaging can be used to find new biomarkers and for studying drug / tissue interactions (pharmacokinetics) in drug discovery as well as for studying biopsies in pathology labs.
		ADE works by transmitting sound waves through the bottom of a fluid reservoir and through the liquid matrix causing a droplet to be ejected from the liquid.
	www.drugresearcher.com /news/ng.asp?n=74693 (630 words)

	Sample Preparation - Liquid Matrices (Site not responding. Last check: 2007-10-17)
		In its current state, MALDI is primarily based on the laser desorption of solid matrix-analyte deposits.
		Very often the compounds used are the traditional MALDI matrix materials.
		Liquid matrices remain the subject of interest of a few research groups, but are not part of the mainstream MALDI methodology.
	www.chemistry.wustl.edu /~msf/damon/samp_prep_liquid.html (414 words)

	Improved Liquid Handling for MALDI Plate Spotting -- Innovadyne Technologies
		One of the great advantages of low volume, non-contact dispensing for MALDI applications is that the smaller spot sizes are more uniform in size and dry more uniformly on the plate.
		These MALDI spotted plates were dispensed using the previously stated conditions for the Biomek FX (b & d) and for the Nanodrop (a & c).
		The resulting MALDI process is shown to be a faster, less expensive, more reliable alternative to using classical liquid handlers such as the Biomek FX.
	www.innovadyne.com /appnote_MALDI.html (1167 words)

	Other MALDI-TOF protocols
		In Method B the matrix is allowed to undergo slow crystallization (18) during the protein extraction period.
		Matrix crystallization is induced by leaving open the top of the microtube (0.5-1 h) with vortexing.
		During extended vortexing periods, the matrix crystals precipitate to the bottom and/or cling to the sides of the microtube and can be retrieved with a micropipettor for MALDI-MS analysis.
	www.hmc.psu.edu /core/oldsite/Maldi/othermalditofprotocols.htm (3990 words)

	Mass Spectrometry Interest Group of the NCI at Frederick (Site not responding. Last check: 2007-10-17)
		MALDI, using 2,5-dihydroxybenzoic acid (DHB) as a matrix, was employed to detect the anticancer drug paclitaxel from a thin section of rat liver tissue which had been incubated in a solution of paclitaxel.
		MALDI MS/MS was then used to detect the presence of paclitaxel in a human ovarian tumor at a concentration of approximately 50 mg/kg.
		Finally, the drug spiperone was detected in incubated rat liver tissue at an approximate level of 25 mg/kg using LD/CI (no MALDI matrix).
	msig.ncifcrf.gov /msig-special-e.html (309 words)

	MassTech - Your Source for AP/MALDI
		On 19 September 2006, SESI was awarded a $4.0M contract by the US Army RDECOM Acquisition Center under the Joint PEO for Chemical and Biological Defense.
		The award is for Phase II development of Wide-Spectrum Bio-ID, a broadband approach for rapid detection and identification of biological agents through integration of proteomics, atmospheric pressure (AP) matrix assisted laser desorption/ionization (MALDI) tandem mass spectrometry (MS/MS), and bio-informatics.
		MP15-242 Comparison of Atmospheric Pressure MALDI IT and Vacuum MALDI TOF-TOF MS Analysis of Bacterial Proteins from Bacillus Spores MALDI Ion Sources
	apmaldi.com /NewsEvents/NewsEvents.htm (869 words)

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