Mass spectrometry—Not just a structural tool: The use of guided ion beam tandem mass spectrometry to determine thermochemistry

Armentrout, P. B.

doi:10.1016/s1044-0305(02)00347-1

Cited by 172 publications

(189 citation statements)

References 78 publications

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“…The measured ion intensities are converted to absolute cross sections using a Beers' law analysis as described previously [60,61]. Absolute uncertainties in the cross section magnitudes are estimated to be ±20%, which are derived largely from errors in the pressure measurement and the effective length of the interaction region.…”

Section: Data Handlingmentioning

confidence: 99%

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Chinthaka¹,

Rodgers²

2012

J. Am. Soc. Mass Spectrom.

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The sodium cation affinities of six commonly used MALDI matrices are determined here using guided ion beam tandem mass spectrometry techniques. The collision-induced dissociation behavior of six sodium cationized MALDI matrices, Na + (MALDI), with Xe is studied as a function of kinetic energy. The MALDI matrices examined here include: nicotinic acid, quinoline, 3-aminoquinoline, 4-nitroaniline, picolinic acid, and 3-hydroxypicolinic acid. In all cases, the primary dissociation pathway corresponds to endothermic loss of the intact MALDI matrix. The cross section thresholds are interpreted to yield zero and 298 K Na + −MALDI bond dissociation energies (BDEs), or sodium cation affinities, after accounting for the effects of multiple ionneutral collisions, the kinetic and internal energy distributions of the reactants, and dissociation lifetimes. Density functional theory calculations at the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G* and MP2(full)/6-311+G(2d,2p)//B3LYP/6-31G* levels of theory are used to characterized the structures and energetics for these systems. The calculated BDEs exhibit very good agreement with the measured values for most systems. The experimental and theoretical Na + −MALDI BDEs determined here are compared with those previously measured by cation transfer equilibrium methods.

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Section: Data Handlingmentioning

confidence: 99%

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Chinthaka¹,

Rodgers²

2012

J. Am. Soc. Mass Spectrom.

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“…[25,26] describes a number of validation criteria for determining the kinetic energy threshold for CID reactions [27][28][29]. These validation experiments are particularly important here because the present work is done with a commercial triple quadrupole MS built for chemical analysis, not for accurate thermochemical measurements [30 -34].…”

Section: Ms and Cid Of Nitrate Complexes Of Group 1 And 2 Metalsmentioning

confidence: 99%

“…These data are also converted to cross sections by the method described by Armentrout, [26,Eq 7] with 0 ϭ 18, n ϭ 1. 1.8 eV (data for the latter value are not shown).…”

Section: Threshold Kinetic Energy Measurements For Nomentioning

confidence: 99%

Tandem mass spectrometry of metal nitrate negative ions produced by electrospray ionization

Byers

Houk

2003

J. Am. Soc. Mass Spectrom.

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M(NO 3 ) xϪ ions are generated by electrospray ionization (ESI) of metal solutions in nitric acid in negative ion mode. Collision-induced reactions of these ions are monitored in a tandem mass spectrometer (MS) of quadrupole-octopole-quadrupole (QoQ) geometry. For Group 1and 2 elements, the M(NO 3 ) x Ϫ ions dissociate into NO 3 Ϫ and neutral metal nitrate molecules. These elements also form some M x (NO 3 ) xϩ1 Ϫ clusters, especially Li ϩ . Metal nitrate ions from transition elements and Group 13 elements fragment into oxo products and also undergo internal electron transfer to leave the M atom in a lower oxidation state. To calibrate the collision energy, the dissociation energy of O-NO 2 Ϫ is found to be 5.55 eV, about 0.76 eV lower than a value derived from thermochemistry. Most studies of small inorganic ions have been done in positive ion mode [14 -18]. Many metal-solvent clusters, e.g., M xϩ (H 2 O) n , n ϭ 1 to 6, are typically formed under "soft" ion extraction conditions [7,17,18]. Highly charged metal ions tend to react with solvent molecules to yield hydroxy or methoxy ions when energetic collision conditions are used to remove solvent during ion extraction. Preserving the original form of the metal ion in positive mode generally requires element-specific optimization of ion extraction conditions and leads to a variety of ion-solvent clusters.Previous work from our group [19] showed that an excess of nitric acid can be used to produce M(NO 3 ) x Ϫ ions in negative ion mode. A single set of ion extraction conditions yields these ions for many elements. This early work was done with only one stage of MS. The present work reports collision-induced dissociation (CID) reactions of these M(NO 3 ) x Ϫ ions in a triple "quadrupole" MS, actually a QoQ instrument. Experimental Samples and Sample PreparationConcentrated nitric acid was purchased from J. T. Baker (Phillipsburg, NJ) and used without further purification. Aliquots of the concentrated acid were mixed with HPLC grade methanol and deionized water (18 M⍀, Barnstead Nanopure, Newton, MA) to form a solvent of 0.05% nitric acid in 25% water:75% methanol. Aliquots of aqueous, acidic metal stock solutions (1000 ppm, Spex Certiprep, Metuchen, NJ ) were diluted with solvent to the desired concentrations.

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“…This stands in contrast to guided ion beam mass spectrometry, wherein these parameters are precisely controlled and thus the resulting data can be used to derive accurate thermochemical quantities. [81,82] Despite these limitations, for the aims of the current work, the experimentally derived dissociation thresholds have provided an excellent means to explore relative trends in bond energies and to test computational predictions. .…”

Section: Dissociation Thresholds Of Alkoxyamine Ionsmentioning

confidence: 99%

Experimental evidence for competitive N O and O C bond homolysis in gas-phase alkoxyamines

Marshall

Gryn’ova

Coote

et al. 2015

International Journal of Mass Spectrometry

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The extensive use of alkoxyamines in controlled radical polymerisation and polymer stabilisation is based on rapid cycling between the alkoxyamine (R1R2NO-R3) and a stable nitroxyl radical (R1R2NO•) via homolysis of the labile O-C bond. Competing homolysis of the alkoxyamine N-O bond has been predicted to occur for some substituents leading to production of aminyl and alkoxyl radicals. This intrinsic competition between the O-C and N-O bond homolysis processes has to this point been difficult to probe experimentally. Herein we examine the effect of local molecular structure on the competition between N-O and O-C bond cleavage in the gas phase by variable energy tandem mass spectrometry in a triple quadrupole mass spectrometer. A suite of cyclic alkoxyamines with remote carboxylic acid moieties (HOOC-R1R2NO-R3) were synthesised and subjected to negative ion electrospray ionisation to yield [M − H]− anions where the charge is remote from the alkoxyamine moiety. Collision-induced dissociation of these anions yield product ions resulting, almost exclusively, from homolysis of O-C and/or N-O bonds. The relative efficacy of N-O and O-C bond homolysis was examined for alkoxyamines incorporating different R3 substituents by varying the potential difference applied to the collision cell, and comparing dissociation thresholds of each product ion channel. For most R3 substituents, product ions from homolysis of the O-C bond are observed and product ions resulting from cleavage of the N-O bond are minor or absent. A limited number of examples were encountered however, where N-O homolysis is a competitive dissociation pathway because the O-C bond is stabilised by adjacent heteroatom(s) (e.g. R3 = CH2F). The dissociation threshold energies were compared for different alkoxyamine substituents (R3) and the relative ordering of these experimentally determined energies is shown to correlate with the bond dissociation free energies, calculated by ab initio methods. Understanding the structure-dependent relationship between these rival processes will assist in the design and selection of alkoxyamine motifs that selectively promote the desirable O-C homolysis pathway. homolysis is a competitive dissociation pathway because the O-C bond is stabilised by adjacent heteroatom(s) (e.g., R 3 = CH 2 F). The dissociation threshold energies were compared for different alkoxyamine substituents (R 3 ) and the relative ordering of these experimentally determined energies is shown to correlate with the bond dissociation free energies, calculated by ab initio methods.Understanding the structure-dependent relationship between these rival processes will assist in the design and selection of alkoxyamine motifs that selectively promote the desirable O-C homolysis pathway.

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Mass spectrometry—Not just a structural tool: The use of guided ion beam tandem mass spectrometry to determine thermochemistry

Cited by 172 publications

References 78 publications

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Tandem mass spectrometry of metal nitrate negative ions produced by electrospray ionization

Experimental evidence for competitive N O and O C bond homolysis in gas-phase alkoxyamines

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