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Columbia, MD, United States

Rationale Understanding the mechanisms of matrix-assisted laser desorption/ionization (MALDI) promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample had been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laser-less matrix-assisted ionization. Methods An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser had been turned off and the MALDI sample removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly and doubly charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. Results The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. Conclusions The observations were partially consistent with a model of the supersonic jet from the inlet capillary accelerating detached particles to kinetic energies suitable for matrix-assisted hypersonic-velocity impact ionization. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd. Source


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 164.92K | Year: 2014

DESCRIPTION (provided by applicant): Significant increase in the efficiency and speed of atmospheric pressure chemical ionization (APCI) in tandem mass spectrometry (MS/MS) will have a profound impact on its applications to the entire analytical field of characterization of drugs, metabolites, lipids, steroids, etc. A broad applicability of APCI-based MS analysis makes it a unique analytical tool specifically targeting trace amounts of many chemical and biological substances. We plan to build a novel APCI ion source based on atmospheric dielectric barrier discharge (DBD) to significantly improve efficiency and specificity of ACPI-MS based detection method. PUBLIC HEALTH RELEVANCE PUBLIC HEALTH RELEVANCE: Atmospheric pressure ionization is a broadly used technique in the analysis of complex chemical and biological samples providing reliable identification of drugs, disease-specific metabolites, steroids, antibiotics, etc. utilizing mass-spectrometers. We plan to develop a novel APCI source that


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 225.00K | Year: 2014

This project (technology transfer opportunity) is aimed at significant improving both the efficiency and performance of the ambient pressure nanoDESI ionization source for the comprehensive analysis of aerosol particles and surfaces including biological tissues by tandem mass spectrometry (MS/MS). Broad applicability of nanoDESI-based MS analysis makes it a unique analytical tool specifically targeting trace amounts of many chemical and biological substances. During implementation of this project we plan to develop and test a microfluidic chip and a novel subatmospheric ionization source which significantly improves efficiency and stability of the nanoDESI technique. The overall objective of this project is to build a robust commercial device facilitating mass analysis of aerosol and biological samples. The development of stable ionization and sample delivery techniques is the aim of Phase I. To facilitate operation of the device, the nanoDESI platform to be built will be made of two halves. One half will be integrated with an interface mounted on the inlet of mass spectrometer, while another half will be mounted on a XY stage holding the sample under analysis. Liquid connection between the halves will be provided by short piece of flexible capillary. Commercial applications include molecular-based aerosol analysis and analysis of biological tissues


Grant
Agency: Department of Health and Human Services | Branch: National Institutes of Health | Program: SBIR | Phase: Phase I | Award Amount: 144.31K | Year: 2016

DESCRIPTION provided by applicant Significant increase in the efficiency of electrospray ionization ESI and atmospheric pressure chemical ionization APCI sources in tandem mass spectrometry MS MS will have a profound impact on single cell MS based analysis and the entire analytical field of characterization of proteins lipids and metabolites Almost ionization efficiency of nanoflow ESI APCI sources makes it a unique analytical tool specifically applicable to the MS based analysis of zeptomole amounts of chemical and biological substances We plan to build a platform combining subatmospheric nanoflow ESI and APCI sources and very efficient ion collector to drastically improve sensitivity and speed of MS based identification of miniscule amount of biomaterials harvested from single cells PUBLIC HEALTH RELEVANCE A platform combining an ultralow flow liquid chromatography separation platform with nanoflow electrospray ionization source and high mass resolution mass spectrometer will be successfully used in the analysis of complex protein mixtures harvested from single cells The platform will provide reliable protein MS based identification from samples that contain zeptomole amounts of these proteins We plan to develop a novel sub atmospheric interface providing highly efficient collection of ions produced by sub atmospheric pressure ion sAPI sources that can be straightforwardly combined with gas phase separation methods This will drastically improve detection limits and accelerate characterization of proteins and metabolites from single cells using high resolution tandem mass spectrometry The platform can be easily incorporated into a design of a variety of commercial tandem mass spectrometers


Grant
Agency: Department of Health and Human Services | Branch: National Institutes of Health | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2016

DESCRIPTION provided by applicant Significant increase in the efficiency of matrix assisted laser desorption ionization MALDI method and utilization of lossless sub atmospheric pressure interface in mass spectrometry MS will have a profound impact on MS based tissue imaging and on the entire analytical field of characterization of proteins lipids and metabolites Proposed increase in ionization efficiency of MALDI sources will make it an indispensable tool for both research laboratories and in clinical settings We plan to build a platform combining atmospheric MALDI source and very efficient ion collector to drastically improve sensitivity and speed of MS based analysis of miniscule amount of biomaterials harvested from tissues PUBLIC HEALTH RELEVANCE A mass spectrometry MS imaging platform utilizing an atmospheric pressure matrix assisted ionization source and ion funnel will be hyphenated with high mass resolution mass spectrometer for the analysis of biological molecules from tissue samples The platform will significantly improve the method sensitivity compared to that achieved using commercial ion sources We plan to develop a novel interface providing highly efficient ionization of analytes harvested from tissue samples and lossless collection of produced ions in the low pressure ion funnel The interface can be straightforwardly combined with gas phase separation methods A use of novel interface will drastically improve detection limits of the MS imaging technology leading to better characterization of protein and metabolite distribution in tissue samples The platform can be easily incorporated into a variety of commercial tandem mass spectrometers

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