Factors affecting reactivity in ammonia chemical ionization mass spectrometry

Keough, T.; DeStefano, Anthony J.

doi:10.1002/oms.1210161205

Cited by 109 publications

(40 citation statements)

References 19 publications

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“…Identification of further peaks in the gas chromatogram has not been carried out. This technique made it possible to gain more evidence on the molecular weight of components in the extract, considering the m/z value of the quasi-molecular ion peak which is usually obtained from nitrogen containing compounds after positive ion chemical ionisation mass spectrometry using ammonia as the reactant gas [7]. This technique made it possible to gain more evidence on the molecular weight of components in the extract, considering the m/z value of the quasi-molecular ion peak which is usually obtained from nitrogen containing compounds after positive ion chemical ionisation mass spectrometry using ammonia as the reactant gas [7].…”

Section: Identification Of L-dopamentioning

confidence: 99%

“…This technique made it possible to gain more evidence on the molecular weight of components in the extract, considering the m/z value of the quasi-molecular ion peak which is usually obtained from nitrogen containing compounds after positive ion chemical ionisation mass spectrometry using ammonia as the reactant gas [7]. The peak at m/z = 215 points to a [M. NH4] + adduct ion [7]. This value for the quasi molecular ion peak should be identicative of a molecular weight of 197 for the originally uncharged compound which appears to be the same as that expected for L-DOPA.…”

Section: Identification Of L-dopamentioning

confidence: 99%

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Production of L-DOPA by cell suspension cultures of Mucuna pruriens

Huizing

Wijnsma

Batterman

et al. 1985

Plant Cell Tiss Organ Cult

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Methods for induction and maintenance of callus as well as cell suspension cultures of Mucuna pruriens are described. The presence of 3-(3, 4-dihydroxyphenyl 1)-L-alanine (L-DOPA) in these cell suspension cultures was demonstrated by means of TLC and HPLC, the latter being equipped with an ultra-violet or a more specific electrochemical detector. Further methods employed were GC, also in combination with mass spectrometry, and thermal desorption chemical ionization mass spectrometry.

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Section: Identification Of L-dopamentioning

confidence: 99%

Section: Identification Of L-dopamentioning

confidence: 99%

Production of L-DOPA by cell suspension cultures of Mucuna pruriens

Huizing

Wijnsma

Batterman

et al. 1985

Plant Cell Tiss Organ Cult

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“…Enhanced detection with long chain fatty acid methyl esters may have occurred because of increased proton affinity of the methyl esters in comparison to the shorter chain compounds 16,17 . Of the different methyl esters, methyl pentadeconoate was chosen as the optimal dopant species for ammonia detection.…”

Section: Resultsmentioning

confidence: 99%

Detection of low molecular weight adulterants in beverages by direct analysis in real time mass spectrometry

Sisco

Dake

2016

Anal. Methods

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Direct Analysis in Real Time Mass Spectrometry (DART-MS) has been used to detect the presence of non-narcotic adulterants in beverages. The non-narcotic adulterants that were examined in this work incorporated a number low molecular weight alcohols, acetone, ammonium hydroxide, and sodium hypochlorite. Analysis of the adulterants was completed by pipetting 1 µL deposits onto glass microcapillaries along with an appropriate dopant species followed by introduction into the DART gas stream. It was found that detection of these compounds in the complex matrices of common beverages (soda, energy drinks, etc.) was simplified through the use of a dopant species to allow for adduct formation with the desired compound(s) of interest. Other parameters that were investigated included DART gas stream temperature, in source collision induced dissociation, ion polarity, and DART needle voltage. Sensitivities of the technique were found to range from 0.001 % volume fraction to 0.1 % volume fraction, comparable to traditional analyses completed using headspace gas chromatography mass spectrometry (HS-GC/MS). Once a method was established using aqueous solutions, , fifteen beverages were spiked with each of the nine adulterants, to simulate real world detection, and in nearly all cases the adulterant could be detected either in pure form, or complexed with the added dopant species. This technique provides a rapid way to directly analyze beverages believed to be contaminated with non-narcotic adulterants at sensitivities similar to or exceeding those of traditional confirmatory analyses.

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“…The ammonium ion has played an important role in mass spectrometry1–5 since the discovery of ion‐molecule reactions and their initiation in chemical ionization 6,. 7 NH 4 + ions are used as mild proton donors applied to organic molecules with higher proton affinities than that of NH 3 (>204 kcal/mol) whereas the possibility of NH 4 + forming complexes with polar organic compounds with proton affinities less than 204 kcal/mol has been applied in chemical ionization mass spectrometry 3,.…”

Section: Methodsmentioning

confidence: 99%

Electrospray ionization mass spectrometric investigation of ammonium ion complexes with anomeric 2,3‐O‐isopropylidene‐1α‐ and ‐1β‐D‐ribofuranosyl azides: anomeric and kinetic isotope effects in ammonium affinities

Kralj

Kocjan²,

Kobe

2001

Rapid Comm Mass Spectrometry

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[Methanol + ammonium acetate] solutions of anomeric 2,3-O-isopropylidene-1alpha- and 1beta-ribofuranosyl azides were investigated by electrospray ionization mass spectrometry (ESI-MS). The compounds included d6-labeled and/or unlabeled isopropylidene groups that enable the identification of peaks characteristic of the ammonium-attached monomeric (MNH4(+)), ammonium-bound homodimeric ([M]2NH4(+)) and heterodimeric ([MNH4M1](+)) complex ions in ESI mass spectra of solutions of a pair of compounds. The intensities of the product ion peaks obtained by the collisionally activated ammonium-bound dimeric ions are related to the secondary isotope effect k(alpha)/k(alphad6) = 0.88 and k(beta)/k(betad6) = 1.25 or to isotope plus anomeric effects k(alpha)/k(betad6) = 1.43 and k(beta)/k(alphad6) = 0.59 in the ammonium affinities of these compounds. The calculations of solely anomeric effects in the ammonium affinities of alpha and beta anomeric compounds obtained from the data presented previously give two series of values: k(alpha)/k(beta) = (k(alpha)/k(alphad6))(k(alphad6)/k(beta)) = 1.49 and k(alphad6)/k(betad6) = (k(alphad6)/k(beta))(k(beta)/k(betad6)) = 2.12 or k(alpha)/k(beta) = (k(alpha)/k(betad6))(k(betad6)/k(beta)) = 1.14 and k(alphad6)/k(betad6) = (k(alphad6)/k(alpha))(k(alpha)/k(betad6)) = 1.63. The disparities of these results indicate the different structures of hydrogen bonding in ammonium-bound dimeric complexes which decompose to monomeric ions with different rate constants. Comparison of experimental results obtained by the qualitative approach of the kinetic method and ammonium affinities of these compounds calculated by the semi-empirical molecular orbital method (AM1) show that the [MNH4M1](+) dimeric complex ions dissociate to the most stable MNH4(+) and M1NH4(+) monomeric ions. The obtained relative order of ammonium affinities of these compounds is: alphad6 > alpha > beta > betad6.

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Factors affecting reactivity in ammonia chemical ionization mass spectrometry

Cited by 109 publications

References 19 publications

Production of L-DOPA by cell suspension cultures of Mucuna pruriens

Production of L-DOPA by cell suspension cultures of Mucuna pruriens

Detection of low molecular weight adulterants in beverages by direct analysis in real time mass spectrometry

Electrospray ionization mass spectrometric investigation of ammonium ion complexes with anomeric 2,3‐O‐isopropylidene‐1α‐ and ‐1β‐D‐ribofuranosyl azides: anomeric and kinetic isotope effects in ammonium affinities

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