195 results about "Matrix-assisted laser desorption/ionization" patented technology

A sample preparation method is disclosed for volatilization and mass spectrometric analysis of nonvolatile high molecular weight molecules. Photoabsorbing molecules having significant sublimation rates at room temperature under vacuum, and preferably containing hydroxy functionalities, are disclosed for use as matrices in matrix-assisted laser desorption / ionization mass spectrometry. The samples are typically cooled in the mass spectrometer to temperatures significantly below room temperature.

Improvements have been made for collection and focusing of ions generated from atmospheric pressure sources such as electrospray, atmospheric pressure chemical ionization, inductively coupled plasma, discharge, photoionization and atmospheric pressure matrix assisted laser desorption ionization. A high transmission electro-optical surface is placed between the source regions and the focusing regions to optimize the field geometries and strengths in each respective region. Compression ratios of greater than 5000 are capable of transferring virtually all ions from large volume dispersive ion regions into ion beam cross-sections of less than 1 mm. Embodiments of this invention are methods and devices for improving sensitivity of mass spectrometry when coupled to atmospheric pressure ionization sources.

Improvements have been made for collecting, focusing, and directing of ions and / or charged particles generated at atmospheric or near atmospheric pressure sources, such as but not limited to, electrospray; atmospheric pressure discharge ionization, chemical ionization, photoionization, and matrix assisted laser desorption ionization; and inductively coupled plasma ionization. A multiple-aperture laminated structure is place at the interface of two pressure regions. Electric fields geometries and strengths across the laminated structure and diameters of the apertures; all of which act to optimize the transfer of the ions from the higher pressure region into the lower pressure region while reducing the gas-load on the lower pressure region. Embodiments of this invention are methods and devices for improving sensitivity of mass spectrometry when coupled to atmospheric, near atmospheric, or higher pressure ionization sources by reducing the gas-load on the vacuum system.

Matrix assisted laser desorption / ionization is performed in a manner to thermalize large analyte ions in a plume of desorbed material for spectroscopic analysis. The thermalized ions have a low or zero mean velocity and are presented at a well-defined instant in time, reducing artifacts and sharpening the spectral peaks. In one embodiment the light is delivered to a matrix or sample holder having a cover, baffle or compartment. The baffle or compartment impedes or contains a plume of desorbed material and the analyte undergoes collisions to lower its mean velocity and directionality. Thus "thermalized" the analyte ions are passed to a mass analysis instrument. In a preferred embodiment an optical fiber butts up against a thin transparent plate on which the specimen resides, with the matrix side in a vacuum acceleration chamber. A mechanical stage moves the specimen in both the x- and y- directions to select a point on the specimen which is to receive the radiation. The use of a fiber optic illuminator allows the entire stage assembly to be subsumed essentially within the dimensions of a conventional stage. In other embodiments, a thermalizing compartment is provided in a capillary tube about the end of the illumination fiber and the sample matrix is deposited along the inner cylindrical wall of the tube, so the capillary forms a migration path to the outlet for thermalization of the desorbed analyte. In other embodiments microstructures having the shape of a small lean-to, overhang or perforated cover plate, or providing a high aspect surface texture, provide the necessary containment to promote thermalization of the released analyte. A thin layer or cover of fibrous or permeable material may also be used to thermalize the analyte before mass analysis, and in other embodiment this material may also act as the substrate. An automated instrument may include a fixed array of illumination fibers which are illuminated at different times to eject samples from a corresponding array of points on the specimen.

The present invention relates to non contact, vision (imaging device / camera) guided, vision-enabled, solenoid valve liquid dispensing systems and methods of using same for automation of complex laboratory workflows and especially useful for a variety of biomedical and other applications including automated front-end sample preparation for matrix assisted laser desorption / ionization (MALDI) mass spectrometry analysis.

Polyurethane polymers bearing multiple reactive groups are readily prepared from easily accessible precursors. The reactive groups of the polymers are then derivatized with binding functionalities for analytes, energy absorbing molecules for matrix assisted laser desorption / ionization mass spectrometry, fluorescent moieties and the like. The reactive groups can also be converted to different reactive groups having a desired avidity or specificity for a selected reaction partner. The polymers are incorporated into devices of use for the analysis, capture, separation, or purification of an analyte. In an exemplary embodiment, the invention provides a substrate coated with a polymer of the invention, the substrate being adapted for use as a probe for a mass spectrometer.

The present invention relates to the use of post source decay (PSD) or collision induced dissociation (CID) direct tissue (DT) MALDI-TOF or DT-MALDI-TOF-TOF mass spectrographic identification of biological molecules in a tissue or cellular sample without the need for further protein extraction. This method provides for studying cells or tissues by direct tissue MALDI (DT-MALDI), thereby substituting in situ protein release for further protein extraction. Mass / intensity data was processed with Mascot© software interrogation of the NCBI database. These results are proof of principle that DT-MALDI, combined with bioinformatics, can directly identify proteins in cells and tissues from their mass spectra.

Provided are ion sources, methods of forming ions and mass analyzer systems. In various embodiments, the present teachings provide ion sources, methods for focusing ions from an ion source, and methods for operating a time-of-flight mass analyzer. In various embodiments, the present teachings relate to matrix-assisted laser desorption / ionization (MALDI) ion sources and methods of MALDI ion source operation, for use with mass analyzers. In various aspects, provided are ion sources and methods of operation thereof that facilitate increasing one or more of sensitivity and resolution of a TOF mass analyzer configured for multiple modes of operation.

This invention relates generally to methods and apparatus for desorption and ionization of analytes for the purpose of subsequent scientific analysis by such methods, for example, as mass spectrometry or biosensors. More specifically, this invention relates to the field of mass spectrometry, especially to the type of matrix-assisted laser desorption / ionization, time-of-flight mass spectrometry used to analyze macromolecules, such as proteins or biomolecules. Most specifically, this invention relates to the sample probe geometry, sample probe composition, and sample probe surface chemistries that enable the selective capture and desorption of analytes, including intact macromolecules, directly from the probe surface into the gas (vapor) phase without added chemical matrix.

A new ionization source named Surface Activated Chemical Ionization (SACI) has been discovered and used to improve the sensitivity of the mass spectrometer. According to this invention the ionization chamber of a mass spectrometer is heated and contains a physical new surface to improve the ionization process. The analyte neutral molecules that are present in gas phase are ionized on this surface. The surface can be made of various materials and may also chemically modified so to bind different molecules. This new ionization source is able to generate ions with high molecular weight and low charge, an essential new key feature of the invention so to improve sensitivity and reduce noise. The new device can be especially used for the analysis of proteins, peptides and other macromolecules. The new invention overcomes some of the well known and critical limitations of the Electrospray (ESI) and Matrix Assisted Laser Desorption Ionization (MALDI) mass spectrometric techniques.

The present invention is directed toward novel matrix elements, generally comprising functionalized carbon nanotubes, for matrix-assisted laser desorption ionization (MALDI)-mass spectroscopy (MS), methods of making such matrix elements, and to methods of using such matrix elements in MALDI-MS applications, particularly for the analysis of biological molecules. In some embodiments, by carefully tuning the absorption characteristics of the matrix element, biomolecular analytes can be sequenced.

The present invention is directed to a simple method for absolute quantification of plasma vitellogenin from two or more different fish species such as Rainbow trout and Atlantic salmon, or Atlantic cod and haddock. In the case of Rainbow trout and Atlantic salmon, plasma samples obtained from control and β-estradiol induced fish were digested with trypsin. A characteristic ‘signature peptide’ was selected and analyzed by high performance liquid chromatography coupled to an electrospray quadrupole-time-of-flight tandem mass spectrometer, using a deuterated homologue peptide as an internal standard. The hybrid tandem mass spectrometer was operated in a ‘pseudo’ selected reaction monitoring mode by which three diagnostic product ions were monitored for identification and quantification purposes. The reproducibility (coefficient of variation ˜5%) and sensitivity (limit of quantification of 0.009 mg / mL) achieved by this simple assay allow it to be considered as an alternative to immunological assays. In the case of Atlantic cod and haddock, the amino acid sequence of the vitellogenin protein has not yet been determined, but, the Atlantic cod vitellogenin has been characterized using a ‘bottom-up’ mass spectrometric approach. Vitellogenin synthesis was induced ‘in vivo’ with β-Estradiol, and subjected to trypsin digestion for characterization by matrix-assisted laser desorption / ionization-Quadrupole-Time-of-flight tandem mass spectrometry. A peptide mass fingerprint was obtained and ‘de novo’ sequencing of the most abundant tryptic peptides was performed by low energy collision induced dissociation-tandem mass spectrometry. Thus, the sequences of various tryptic peptides have been elucidated. It has also been determined that Atlantic cod vitellogenin shares a series of common peptides with the two different known vitellogenin sequences of Haddock, a closely related species. There are also disclosed novel isolated signature peptides, namely Thr-Tyr-Phe-Ala-Gly-Ala-Ala-Ala-Asp-Val-Leu-Glu-Val-Gly-Val-Arg, Asp Leu Gly Leu Ala Tyr Thr Glu Lys, Phe Phe Gly Gln Glu Ile Ala Asn Ile Asp Lys, Glu Ile Val Leu Leu Gly Tyr Gly Thr Met Ile Ser Lys and Tyr Glu Ser Phe Ala Val Ala Arg.