Fragmentation Reactions of All 64 Deprotonated Trinucleotide and 16 Mixed Base Tetranucleotide Anions via Tandem Mass Spectrometry in an Ion Trap.

2000 ◽  
Vol 53 (4) ◽  
pp. 307 ◽  
Author(s):  
Ana K. Vrkic ◽  
Richard A. J. O'Hair ◽  
Simon Foote
Keyword(s):  
Mass Spectrometry ◽  
Proton Transfer ◽  
Ion Trap ◽  
Fragmentation Pathway ◽  
Intramolecular Proton Transfer ◽  
Base Loss ◽  
Phosphodiester Bond ◽  
Neutral Base ◽  
Fragmentation Reactions ◽  
Direct Dissociation

The gas-phase fragmentation reactions of the [M–H]– ions derived from all 64 trinucleotides and 16 isomeric tetranucleotides each containing adenine, thymine, guanine and cytosine were examined using multistage mass spectrometry (MS/MS and MS3) collision-induced dissociation in an ion trap mass spectrometer. The initial fragmentation pathway involved neutral base loss predominantly from the 5´ terminus, along with minor 3´ and internal base loss in the order A > T > G > C to form [M–H–BH]– ‘non-sequence’ ions. The resultant [M–H–BH]– ions often fragment via intramolecular proton transfer with concomitant cleavage of the 3´ C–O phosphodiester bond to yield an ion–molecule complex, which undergoes either direct dissociation or proton transfer to yield the w-type or (a–B)-type ‘sequence’ ions respectively.

scholarly journals Decarboxylation versus Acetonitrile Loss in Silver Acetate and Silver Propiolate Complexes, [RCO2Ag2(CH3CN)n]+ (where R = CH3 and CH3C≡C; n = 1 and 2)

2015 ◽  
Vol 68 (9) ◽  
pp. 1385 ◽  
Author(s):  
Jiawei Li ◽  
George N. Khairallah ◽  
Richard A. J. O'Hair
Keyword(s):  
Dft Calculations ◽  
Gas Phase ◽  
Density Functional ◽  
Ion Trap ◽  
Fragmentation Pathway ◽  
Binding Energies ◽  
Silver Acetate ◽  
Bond Forming ◽  
Fragmentation Reactions ◽  
A Minor

Gas-phase experiments using collision-induced dissociation in an ion trap mass spectrometer have been used in combination with density functional theory (DFT) calculations (at the B3LYP/SDD6–31+G(d) level of theory) to examine the competition between decarboxylation and loss of a coordinated acetonitrile in the unimolecular fragmentation reactions of the silver acetate and silver propiolate complexes, [RCO2Ag2(CH3CN)n]+ (where R = CH3 and CH3C≡C; n = 1 and 2), introduced into the gas-phase via electrospray ionisation. When R = CH3, loss of acetonitrile is the sole reaction channel observed for both complexes (n = 1 and 2), consistent with DFT calculations, which highlight that the barriers for decarboxylation 2.18 eV (n = 2) and 1.96 eV (n = 1) are greater than the binding energies of the coordinated acetonitriles (1.60 eV for n = 2; 1.64 eV for n = 1). In contrast, when R = CH3C≡C, decarboxylation is the main fragmentation pathway observed for both complexes (n = 1 and 2), with loss of acetonitrile only being a minor product channel. This is consistent with DFT calculations, which reveal that the barriers for decarboxylation are 1.17 eV (n = 2) and 1.16 eV (n = 1), which are both below the binding energies of the coordinated acetonitriles (1.55 eV for n = 2; 1.56 eV for n = 1). The barrier for decarboxylation of [CH3C≡CCO2Ag2]+ is 1.22 eV, which is less than the 2.06 eV reported for decarboxylation of [CH3CO2Ag2]+ (Al Sharif et al. Organometallics, 2013, 32, 5416). The observed ease of decarboxylation of silver propiolate complexes in the gas-phase is consistent with the recently reported use of silver salts in metal catalysed decarboxylative C–C and C–X bond forming reactions of propiolic acids.

Gas Phase Reactions of Trimethylborate with the [M − H]− Ions of Nucleotides and Their Non-Covalent Homo- and Heterodimer Complexes

2003 ◽  
Vol 56 (5) ◽  
pp. 389 ◽  
Author(s):  
Ana K. Vrkic ◽  
Richard A. J. O'Hair
Keyword(s):  
Gas Phase ◽  
Mass Spectrometer ◽  
Ion Trap ◽  
Quadrupole Ion Trap ◽  
Methanol Molecule ◽  
Collision Induced Dissociation ◽  
Base Loss ◽  
Gas Phase Reactions ◽  
Ion Trap Mass Spectrometer ◽  
Neutral Base

Trimethylborate (TMB) reacts with deprotonated monomer, homo-, and heterodimer ions of nucleotides (2′-deoxyadenosine-5′-monophosphate [dAMP], 2′-deoxycytidine-5′-monophosphate [dCMP], 2′-deoxyguanosine-5′-monophosphate [dGMP], and 2′-deoxythymidine-5′-monophosphate [dTMP]) in a quadrupole ion trap mass spectrometer by addition with concomitant elimination of one or two methanol molecules (monomers), one or three methanol molecules (homodimers), and three methanol molecules (heterodimers). The mode of reaction appears to influence the observed rates, with the loss of only one methanol molecule corresponding to the fastest rate. There appears to be a structure–reactivity correlation for the monomers, with the [dGMP – H]– ions (which adopt a syn conformation of the guanine moiety) reacting fastest with TMB through the loss of only one methanol molecule. No such structure–reactivity trends are observed for the homo- and heterodimers. In addition, the collision-induced dissociation (CID) reactions of the [(dXMP)n − H]– (n = 1 or 2) as well as the [dXMP + dYMP – H + (CH3O)3B – 3(CH3OH)]– ions (where nucleotides X, Y = A, C, G, or T) were studied. The latter fragment to form [dXMP – H + BPO4]– and [dXMP – 3H + BPO3]– ions (where X = A, C, G, or T), while [dXMP – H]– ions fragment by neutral base loss. The homo- and heterodimers fragment to form [dXMP – H]– and [dXMP + HPO3]– ions, and the relative abundances of the [dXMP – H]– monomer ions from the heterodimers led to the following acidity order: dGMP ≈ dTMP > dCMP > dAMP.

Two additional advantages of proton-transfer ion trap mass spectrometry

2003 ◽  
Vol 18 (1) ◽  
pp. 133-134 ◽  
Author(s):  
C. Warneke ◽  
S. Rosén ◽  
E. R. Lovejoy ◽  
J. A. de Gouw ◽  
R. Fall
Keyword(s):  
Mass Spectrometry ◽  
Proton Transfer ◽  
Ion Trap ◽  
Ion Trap Mass Spectrometry

Fragmentation Pathway of Acevaltrate by Electro-Spray Ionization Ion-Trap Mass Spectrometry

2011 ◽  
Vol 361-363 ◽  
pp. 1745-1747
Author(s):  
Yong Gang Liu ◽  
Yong Liu ◽  
Qun Ma
Keyword(s):  
Mass Spectrometry ◽  
Ion Trap ◽  
Fragmentation Pathway ◽  
The Other ◽  
Collision Induced Dissociation ◽  
Ion Trap Mass Spectrometry ◽  
Electro Spray Ionization ◽  
Branched Chain ◽  
Positive Ion

The fragmentation pathway of acevaltrate was investigated by electro-spray ionization ion-trap mass spectrometry．Under the positive ion mode, pseudo-molecular [M+Na]+ could be easily obtained，and fragmentation pathway presented a certain regularity. One of the major fragmentations observed in the collision induced dissociation(CID) spectrum was loss of branched-chain, and the other was that three-membered oxygen-containing rings would break into aldehyde. These results might be used to forecast the structures of irodoids.

TRIGLYCERIDE COMPOSITION OF SIXTEEN STRAINS OF MARINE DIATOM

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Lily M.G. Panggabean ◽  
Abdullah Rasyid ◽  
Zarrah Duniani ◽  
Yana Meliana ◽  
Indah Kurniasih
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acid ◽  
Double Bond ◽  
Unsaturated Fatty Acid ◽  
Ion Trap ◽  
Carbon Chain ◽  
Highly Unsaturated Fatty Acid ◽  
Marine Diatom ◽  
Ion Trap Mass Spectrometry ◽  
Spectra Analysis

Trigliceride or triacylglicerol (TAG) composition in crude oil of sixteen strain of marine diatom has been detected by spectra analyses on an Electrospray - Ion Trap – Mass Spectrometry (ESI-IT-MS) HCT Bruker-Daltonic GmbH instrument with AgNO3 used as coordination ionization agent. Biomass samples of each microalga strain were taken from early and late stationary cultures in f/2 enriched seawater and algal oils were extracted according to Bligh and Dyer. Results from spectra analysis showed that P-Pt-P (C16:0-C16:1-C16:0) were distinguished in TAG from diatom strains Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.1, Thalasiossira sp.2, Thalasiossira sp.3, Navicula sp. 1, Navicula sp. 2, Navicula sp. 3, Navicula sp. 4, Nitzschia sp. 2 and Amphora sp. In contrast, TAGs in Melosira sp. included P-P-P (C16:0-C16:0-C16:0) and P-P-O (C16:0-C16:0-C18:1) were identified. TAGs from Chaetoceros sp. were the most varies among samples, i.e. P-Pt-P (C16:0-C16:1-C16:0), A-P-M (C20:4-C16:0-C14:0), P-Pt-Lt (C16:0-C16:1-C18:3), P-Pt-A (C16:0-C16:1-C20:4), D-P-P (C22:6-C16:0-C16:0), A-Ln-P (C20:4-C18:2-C16:0). Various TAGs were also detected in Nitzschia sp.2, i.e. P-Pt-M (C16:0-C16:1-C14:0), P-Pt-P (C16:0-C16:1-C16:0), P-Pt-S (C16:0-C16:1-C18:0), P-Pt-A (C16:0-C16:1-C20:4). TAGs composition in Skeletonema strains that similar to those in Nitzschia sp.1 has longer carbon, i.e. P-P-O (C16:0-C16:0-C18:1), P-O-O (C16:0-C18:1-C18:1) and O-O-O (C18:1-C18:1-C18:1). TAGs with longer carbon chain and more double bond including highly unsaturated fatty acid C20:4 were increased with culture age in diatoms Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.2, Navicula sp.1 and Nitzschia sp. 2.Keywords: diatom, TAG, ESI-IT-MS, f/2, early and late stationary

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