Gas-phase dissociation reactions of protonated saxitoxin and neosaxitoxin

Sleno, Lekha; Volmer, Dietrich A.; Kovačević, Borislav; Maksić, Zvonimir B.

doi:10.1016/j.jasms.2003.11.013

Cited by 24 publications

(19 citation statements)

References 47 publications

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“…The two compounds exhibited a large number of different product ion species of significant abundance throughout the entire mass range. Not surprisingly, the spectra appear quite similar to the triplequadrupole MS/MS spectra reported before, as the collision conditions in q 2 were almost the same [18]. There are also similarities between the ionic products of STX and NEO, indicating parallel dissociation mechanisms.…”

Section: Resultssupporting

confidence: 78%

“…Two PSP toxins, saxitoxin (STX) and 1-N-hydroxysaxitoxin (Neosaxitoxin, NEO) (Scheme 1), were chosen as test molecules. The large number of functional groups within a rather small skeletal structure of the two compounds and the possibility for resonance stabilization of fragment ions after dissociation lead to unusually rich product ion mass spectra [18]. This complexity is illustrated in Figure 1, showing QqTOF CID spectra of the MH ϩ ions of STX and NEO.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, many ions are not the result of a simple 16 Da mass shift due to the additional -OH group of NEO at N-1. Although we are not concerned here with mechanistic details (the interested reader is referred to reference [18] for a comprehensive description of the gas-phase dissociation behavior of the PSPs), we have included a few interesting new discoveries related to the gas-phase ion chemistry of STX and NEO that we made while comparing FT-ICR and QqTOF performance (vide infra). The experiments described here focus on the range 137 Ͻ m/z Ͻ 300/316 (MH ϩ , STX/NEO), because it includes many abundant ionic products.…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, the observation of peaks yielding poor mass accuracy of the QqTOF system offers an unexpected but convenient way for detecting the presence of multiple species in a composite peak, many of which had previously escaped our attention when investigating the triple-quadrupole CID behavior of PSPs [18]. Some of the more important examples are illustrated in the following section.…”

Section: The Refined Approach: Monoisotopic Activation Cyclesmentioning

confidence: 99%

“…We have recently described such an example, observed in the triple-quadrupole CID analysis of protonated molecules of paralytic shellfish poisoning (PSP) toxins (Scheme 1) [18]. Not only did the spectra exhibit an unusually "rich" variety of product ions but they also showed numerous isobaric species as well as interfering M ϩ 1 contributions from 13 C 12 C cϪ1 species.…”

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confidence: 99%

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Assigning product ions from complex MS/MS spectra: The importance of mass uncertainty and resolving power

Sleno

Volmer

Marshall

2005

J. Am. Soc. Mass Spectrom.

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This study offers a unique insight into the mass accuracy and resolving power requirements in MS/MS analyses of complex product ion spectra. In the examples presented here, accurate mass assignments were often difficult because of multiple isobaric interferences and centroid mass shifts. The question then arose whether the resolving power of a medium-resolution quadrupole time-of flight (QqTOF) is sufficient or high-resolution Fourier-transform ion cyclotron resonance (FT-ICR) is required for unambiguous assignments of elemental compositions. For the comparison, two paralytic shellfish poisons (PSP), saxitoxin (STX) and neosaxitoxin (NEO), with molecular weights of 299 and 315 g·mol Ϫ1 , respectively, were chosen because of the high peak density in their MS/MS spectra. The assessment of QqTOF collision-induced dissociation spectra and FT-ICR infrared multiphoton dissociation spectra revealed that several intrinsic dissociation pathways leading to isobaric fragment ions could not be resolved with the QqTOF instrument and required FT-ICR to distinguish very close mass differences. The second major source of interferences was M ϩ 1 species originating from coactivated 13 C 12 C cϪ1 ion contributions of the protonated molecules of the PSPs. The problem in QqTOF MS results from internal mass calibration when the MH ϩ ions of analyte and mass calibrant are activated at the same time in the collision or trapping cell. Although FT-ICR MS readily resolved these interfering species, the QqTOF did not provide resolving power Ͼ20,000 (full width at half maximum) required to separate most isobaric species. We were able to develop a semi-internal QqTOF calibration technique that activated only the isolated 12 C isotope species of the protonated molecules, thus reducing the M ϩ 1 interferences significantly. In terms of overall automated elemental formulas assignment, FT-ICR MS achieved the first formula hit for 100% of the product ions, whereas the QqTOF MS hit rate was only 56 and 65% for STX and NEO product ions, respectively. External mass calibration from commercial FT-ICR and QqTOF instruments gave similar results. ass-based structural identification of drugs and their metabolites frequently employs combinations of collision-induced dissociation (CID) analyses on triple quadrupole and ion trap mass analyzers. These methods often provide adequate information for determining the sites of modification for structural analogs [1][2][3][4][5]. In those cases, however, in which the variety of fragment ions is limited and the spectra do not allow unambiguous structure assignments, tentatively identified structures are often further examined by high-resolution mass spectrometry, from which elemental compositions can be obtained. In these experiments, it is required to measure the mass-tocharge ratios with the smallest mass uncertainties possible, in particular if the methodologies are part of routine structure identification protocols. Ideally, unattended and automated analytical routines with sufficient resolution and mass accu...

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: The Refined Approach: Monoisotopic Activation Cyclesmentioning

confidence: 99%

mentioning

confidence: 99%

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Assigning product ions from complex MS/MS spectra: The importance of mass uncertainty and resolving power

Sleno

Volmer

Marshall

2005

J. Am. Soc. Mass Spectrom.

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Detection of Paralytic Shellfish Poisoning Toxins in Molluscs

Burrell

Turner

2017

Analysis of Food Toxins and Toxicants

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Cover Picture: Laves Phases, γ‐Brass, and 2×2×2 Superstructures: A New Class of Quasicrystal Approximants and the Suggestion of a New Quasicrystal (Chem. Eur. J. 22/2008)

Berger

Johnson

Nebgen

et al. 2008

Chemistry A European J

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Reversible binding of CO2 …︁ can be realized with borane–phosphane frustrated Lewis pairs (FLPs). In their Communication on , G. Erker et al. describe how the greenhouse gas CO2 is captured to form both cyclic and acyclic adducts through PC and OB bond formation. The reaction is reversed and CO2 released when the temperature of the solution is raised. Theoretical analysis describes CO2 binding by FLPs as a synchronous concerted reaction.

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Gas-phase dissociation reactions of protonated saxitoxin and neosaxitoxin

Cited by 24 publications

References 47 publications

Assigning product ions from complex MS/MS spectra: The importance of mass uncertainty and resolving power

Assigning product ions from complex MS/MS spectra: The importance of mass uncertainty and resolving power

Detection of Paralytic Shellfish Poisoning Toxins in Molluscs

Cover Picture: Laves Phases, γ‐Brass, and 2×2×2 Superstructures: A New Class of Quasicrystal Approximants and the Suggestion of a New Quasicrystal (Chem. Eur. J. 22/2008)

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