Atmospheric Ionization Source Research Articles

Arc Plasma-Based Dissociation Device: Fingerprinting Mass Spectrometric Analysis Realized at Atmospheric Condition.

Fingerprinting mass spectrometric analysis at atmospheric conditions has been realized using an arc plasma-based dissociation (APD) device. Because of its high energy, high temperature, and unique chemical reactivity, the thermal plasma can induce dissociation of neutral molecules or ions produced by atmospheric ion sources. Both even/odd electron (fragment) ions would be generated to provide fingerprinting structural information and molecular weight of the compounds simultaneously. Meanwhile, elimination and aromatization were observed as special dissociation patterns in this device, which can be applied in the differentiation of isomers. The good compatibility with atmospheric ion sources is demonstrated by coupling the device with nanoelectrospray ionization (nano-ESI) and zero volt paper spray ionization (PSI), respectively. With erythromycin as the tuning standard, informative dissociation spectra of various compounds can be reproducible, making it possible to establish an arc plasma-based dissociation spectra database. This device allows fingerprinting mass spectrometric analysis, with no need for harsh vacuum conditions and is promising for making a breakthrough in making up the deficiency of atmospheric ionization techniques.

The Reaction of Sulfur Dioxide Radical Cation with Hydrogen and its Relevance in Solar Geoengineering Models.

SO2 has been proposed in solar geoengineering as a precursor of H2 SO4 aerosol, a cooling agent active in the stratosphere to contrast climate change. Atmospheric ionization sources can ionize SO2 into excited states of , which quickly reacts with trace gases in the stratosphere. In this work we explore the reaction of with excited by tunable synchrotron radiation, leading to ( ), where H contributes to O3 depletion and OH formation. Density Functional Theory and Variational Transition State Theory have been used to investigate the dynamics of the title barrierless and exothermic reaction. The present results suggest that solar geoengineering models should test the reactivity of with major trace gases in the stratosphere, such as H2 since this is a relevant channel for the OH formation during the nighttime when there is not OH production by sunlight. OH oxides SO2 , triggering the chemical reactions leading to H2 SO4 aerosol.

Spatial localisation of curcumin and rapid screening of the chemical compositions of turmeric rhizomes (Curcuma longa Linn.) using Direct Analysis in Real Time-Mass Spectrometry (DART-MS)

Curcumin is a potent antioxidant agent having versatile biological activities is present in turmeric rhizomes (Curcuma longa Linn.). Powder of turmeric rhizomes is consumes as curry spicy worldwide, especially in Asia. In this study, we demonstrate that, bioactive curcumin and its analog demethoxycurcumin are chiefly concentrated in the pith rather than the other parts of the turmeric rhizomes and it was discovered using modern atmospheric ionisation source ‘Direct Analysis in Real Time’ (DART) connected with an Ion Trap Mass Spectrometry. In addition, all the major components present in turmeric rhizomes were detected in positive and/or in negative ion mode using DART.

Surface Charge Density Driven Delivery of Drugs and Plasmid DNA to Skin Using Atmospheric Ion Sources

Low energy ion deposition to create electric fields in tissue provides an attractive means to electrically mediate and induce delivery of normally non-permeant molecules to tissue cells in vivo. Electrically mediated therapies have progressed to clinical demonstration yet require anesthetic to minimize patient discomfort. Ions generated at atmospheric pressure may be applied to the skin surface to produce an electric field in the tissue leading to an effective delivery of molecules to cells. Such processes are charge limited and therefore do not produce high current in the tissue.

Surface Charge Density Driven Delivery of Drugs and Plasmid DNA to Skin Using Atmospheric Ion Sources

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An Insect-sized Atmospheric Ion Source Localization Robot for the Evaluation of Odor Source Localization Algorithms of Insects

An Insect-sized Atmospheric Ion Source Localization Robot for the Evaluation of Odor Source Localization Algorithms of Insects

A novel method for the collimation of ions at atmospheric pressure

Measured gains in source-to-target ion transmission of well over two orders of magnitude are reported from the application of a robust and versatile electrostatic lens that requires no voltage supply and consumes negligible power. When exposed to an ion flux across a potential gradient, a series of electrically-floating circular conductors automatically attain a profile of convergent potentials. This passive ion lens is used to collimate atmospheric ion source currents that range from 30 pA to 7 nA, increasing the ion signal strength at the target by factors of 20–130 times that of the unaided signal.

Atmospheric pressure MALDI/ion trap mass spectrometry.

A new sample ionization technique, atmospheric pressure matrix-assisted laser desorption/ionization (AP MALDI), was coupled with a commercial ion trap mass spectrometer. This configuration enables the application-specific selection of external atmospheric ionization sources: the electrospray/APCI (commercially available) and AP MALDI (built in-house), which can be readily interchanged within minutes. The detection limit of the novel AP MALDI/ion trap is 10-50 fmol of analyte deposited on the target surface for a four-component mixture of peptides with 800-1700 molecular weight. The possibility of peptide structural analysis by MS/MS and MS3 experiments for AP MALDI-generated ions was demonstrated for the first time.

HPLC-UV Atmospheric Pressure Ionization Mass Spectrometry Determination of the Dopamine D2 Agonist N-0923 and Its Major Metabolites After Oxidative Metabolism by Rat-, Monkey-, and Human Liver Microsomes

An innovative custom-built atmospheric ionization source afforded an opportunity to perform on-line LC/MS analysis and to obtain identification of metabolites without need to rely on radioactive profiling. An HPLC with a UV detector coupled to a modified R 3010 triple quadrupole mass spectrometer was used in which nitrogen gas effectively prevented the clustering of ions with polar solvent molecules as well as acting as the nebulizing gas for the ionspray LC/MS interface. This approach was useful in elucidating the oxidative metabolism of the potent dopamine D2 agonist 2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin in rat-, monkey-, and human liver microsome preparations. Microsomes from monkey showed the highest metabolic activity, with 8.3 nmol · min−1 · mg−1 protein; the human material resulted in the lowest, 1.2 nmol · min−1 · mg−1 protein. Metabolic profiling showed that the three species produced the same metabolites, but to different extents. Liver microsomes metabolized the (-) enantiomer to...

Application of high-performance liquid chromatography/atmospheric pressure ionization mass spectrometry for the analysis of non-volatile compounds

The combination of a high-performance liquid chromatograph and a magnetic type mass spectrometer with an atmospheric ionization source has been applied for analyses of thermolabile compounds, i.e. antibiotics, amino acids and glycosphingolipids. Chromatography was performed on a 4 mm i.d. x 150 mm column packed with 5 μm ODS at a flow rate of 1 ml min−1. The liquid chromatography/atmospheric pressure ionization (LC/API) magnetic-type mass spectrometer provides not only an abundant pseudo-molecular ion but also fragment ions which give a structural information resulting from collision-induced dissociation at the differential pumping region of the liquid chromatograph/mass spectrometer interface. The isomers of kanamycins could be differentiated from each other on the basis of their mass spectra obtained at the relatively higher drift voltage applied. LC/API mass spectra of leucine and isoleucine were very similar, but it was easy to differentiate one from another by checking the existence of the ions at m/z 43 or m/z 57 in their mass spectra. The LC/API mass spectra of glucosylceramides showed [MH]+ ions of good abundance and significant fragment ions useful for chemical characterization at a proper drift voltage setting in a controlled and reproducible manner.