‘Wrong‐way‐round’ Electrospray Ionization of Amino Acids

Mansoori, Bashir A.; Volmer, Dietrich A.; Boyd, Robert K.

doi:10.1002/(sici)1097-0231(19970630)11:10<1120::aid-rcm976>3.3.co;2-h

Cited by 82 publications

(134 citation statements)

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“…On the other hand, Hiraoka et al [7] observed that both compounds produced strong positive ion signals when electrosprayed from ammonia solutions. In extension of this work, Mansoor et al [8] later stated that the ion intensities produced from electrosprayed amino acid solutions showed only little variation over a pH range from 3 to 11. Due to the good response, and to detect only compounds of interest, we used the selected ion monitoring (SIM) mode and set the MSD to record the deprotonated molecules m/z 132 ([M-H] -of aspartic acid) and m/z 146 ([M-H] -of the internal standard glutamic acid).…”

Section: Resultsmentioning

confidence: 68%

Feasibility study: fast liquid chromatography?mass spectrometry for the quantification of aspartic acid in an aspartate drug

Schmidt

2003

Analytical and Bioanalytical Chemistry

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We have studied the feasibility of fast high-performance liquid chromatography coupled to electrospray ionization mass spectrometry in the selected ion monitoring mode for the quantitative determination of aspartic acid in an aspartate drug. Internal standardization was required, but mass spectrometric detection allowed for very short retention times of approximately 0.5 min for the analyte and the internal standard without chromatographic separation. The analytical system was found stable, as demonstrated by multiple injections giving a coefficient of variation of 4% for the peak area ratio of aspartic acid and glutamic acid. Calibrations were linear between 0.5 ng and 150 ng aspartic acid injected, with accuracies between 99.8% and 102% found for the back-calculated amounts. Investigation of several drug batches gave reasonable results. Therefore, the method appeared feasible for the determination of aspartic acid in an aspartate drug from 0.3 wt% to 100 wt% aspartic acid.

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Section: Resultsmentioning

confidence: 68%

Feasibility study: fast liquid chromatography?mass spectrometry for the quantification of aspartic acid in an aspartate drug

Schmidt

2003

Analytical and Bioanalytical Chemistry

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“…The observation of molecular ion peaks under these conditions suggests , wrong-way-round' ionization is possible for small molecules as well as for the larger molecules previously studied by Fenselau and coworkers [17]. Other more recent work by Boyd and coworkers has shown that this is true for amino acids [18]. However, since the molecular ion signal is diminished in mildly acidic media (HOAc) and completely suppressed under highly acidic conditions (TFA), the signal could possibly be accounted for by those molecules that are still partially ionized under the milder conditions.…”

Section: Discussionmentioning

confidence: 67%

Adduct formation in electrospray ionization. Part 1: Common acidic pharmaceuticals

Schug

McNair

2002

J. Sep. Science

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This study focuses on pseudo-molecular ion formation in electrospray ionization mass spectrometry (ESI-MS) of six anti-inflammatory pharmaceuticals with similar functionality. The formation of particular pseudo-molecular ions depends on ion affinity and molecular structure of the analyte as well as the solvent/buffer conditions used. Six common anti-inflammatory agents are mixed 1:1 with six different acetonitrile/aqueous buffer solutions at varying concentrations. The analytes are ibuprofen, carprofen, naproxen, ketoprofen, flurbiprofen, and fenoprofen. The pK a and surface activity of the analytes and the pH, concentration, and type of the solvent system strongly affect the ions formed [1,2]. The additives are common liquid chromatography (LC) mobile phase modifiers.The spectral intensities of three major pseudo-molecular ions were measured by flow injection analysis ESI-MS. The ions studied correspond to the deprotonated molecular ion ([M -H] -), a deprotonated dimer ion ([2M -H] -), and a deprotonated dimer ion pair with sodium ([2M -2H+Na] -). These ions were chosen due to their high relative abundance in a majority of the spectra.The pK a of the analytes studied range from 4.1 to 4.4, due to their aromatic acetic acid moiety. The common carboxylic acid group facilitates ESI of the compounds in the negative ionization mode. The changes in molecular structure of these model compounds allows for a wide variety of solution interactions. Some analytes are effectively declustered under the set conditions creating an intense [M -H] -peak, whereas others prefer to form dimers or complexes with sodium.

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“…Besides, using high-pH resistant reversed phase C18 columns, it was possible to investigate the influence of mobile phase pH on ESI-MS responsivities of a broad range of chemical entities of pharmaceutical interest, where analyte signals were significantly increased under basic pH conditions [55,59]. Studying ESI of amino acids, Mansoori and coworkers defined this phenomenon as ''wrong-way-round'' (WWR) ionization and outlined the absence of a simple and/or predictive dependency of analyte ESI-MS response on eluent pH [60].…”

Section: Discussionmentioning

confidence: 99%

Alkaline conditions in hydrophilic interaction liquid chromatography for intracellular metabolite quantification using tandem mass spectrometry

Teleki

Santiago

Takors

2015

Analytical Biochemistry

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‘Wrong‐way‐round’ Electrospray Ionization of Amino Acids

Cited by 82 publications

References 0 publications

Feasibility study: fast liquid chromatography?mass spectrometry for the quantification of aspartic acid in an aspartate drug

Feasibility study: fast liquid chromatography?mass spectrometry for the quantification of aspartic acid in an aspartate drug

Adduct formation in electrospray ionization. Part 1: Common acidic pharmaceuticals

Alkaline conditions in hydrophilic interaction liquid chromatography for intracellular metabolite quantification using tandem mass spectrometry

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