Trace detection of inorganic oxidants using desorption electrospray ionization (DESI) mass spectrometry

AbstractDesorption electrospray ionization (DESI), an established ambient ionization method in mass spectrometry (MS) for the analysis of organic compounds, is applied here to trace detection of inorganic salts, including inorganic oxidants. In-situ surface analysis of targeted compounds, including nitrogen-, halogen- and sulfur-salts, down to sub-nanogram levels, was performed using DESI-MS. Successful experiments were carried out in both the negative and the positive ion modes; simple anions and cations as well as small cluster ions were observed. Various surfaces are examined and surface porosity effects were briefly explored. Absolute detection limits on porous polytetrafluoroethylene (PTFE) of 120 pg (surface concentration 0.07 ng mm−2) and 50 pg (surface concentration 0.03 ng mm−2), were achieved for sodium chlorate and sodium perchlorate, respectively. The compounds of interest were examined in the presence of a hydrocarbon mixture to assess matrix effects: only a two- or three-fold decrease in the target ion intensity was observed. Commercial fireworks were analyzed to determine perchlorate salts in complex mixtures. This work demonstrates the potential applicability of ambient ionization mass spectrometry to forensic investigations involving improvised explosives.

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Ambient Ionization Mass Spectrometry Imaging by Desorption Electrospray Ionization (DESI)

Journal of the Mass Spectrometry Society of Japan ◽

10.5702/massspec.s19-26 ◽

2019 ◽

Vol 67 (4) ◽

pp. 112-116

Author(s):

Akira Motoyama ◽

Keishi Kihara

Keyword(s):

Mass Spectrometry ◽

Electrospray Ionization ◽

Mass Spectrometry Imaging ◽

Desorption Electrospray Ionization ◽

Ambient Ionization ◽

Ionization Mass Spectrometry ◽

Ionization Mass ◽

Ambient Ionization Mass Spectrometry

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Intraoperative assessment of isocitrate dehydrogenase mutation status in human gliomas using desorption electrospray ionization–mass spectrometry

Journal of Neurosurgery ◽

10.3171/2018.8.jns181207 ◽

2020 ◽

Vol 132 (1) ◽

pp. 180-187 ◽

Cited By ~ 3

Author(s):

Clint M. Alfaro ◽

Valentina Pirro ◽

Michael F. Keating ◽

Eyas M. Hattab ◽

R. Graham Cooks ◽

...

Keyword(s):

Mass Spectrometry ◽

Electrospray Ionization ◽

Isocitrate Dehydrogenase ◽

Tumor Resection ◽

Desorption Electrospray Ionization ◽

Extent Of Resection ◽

Ionization Mass ◽

Idh Mutation ◽

Mutation Status ◽

Desi Ms

OBJECTIVEThe authors describe a rapid intraoperative ambient ionization mass spectrometry (MS) method for determining isocitrate dehydrogenase (IDH) mutation status from glioma tissue biopsies. This method offers new glioma management options and may impact extent of resection goals. Assessment of the IDH mutation is key for accurate glioma diagnosis, particularly for differentiating diffuse glioma from other neoplastic and reactive inflammatory conditions, a challenge for the standard intraoperative diagnostic consultation that relies solely on morphology.METHODSBanked glioma specimens (n = 37) were analyzed by desorption electrospray ionization–MS (DESI-MS) to develop a diagnostic method to detect the known altered oncometabolite in IDH-mutant gliomas, 2-hydroxyglutarate (2HG). The method was used intraoperatively to analyze tissue smears obtained from glioma patients undergoing resection and to rapidly diagnose IDH mutation status (< 5 minutes). Fifty-one tumor core biopsies from 25 patients (14 wild type [WT] and 11 mutant) were examined and data were analyzed using analysis of variance and receiver operating characteristic curve analysis.RESULTSThe optimized DESI-MS method discriminated between IDH-WT and IDH-mutant gliomas, with an average sensitivity and specificity of 100%. The average normalized DESI-MS 2HG signal was an order of magnitude higher in IDH-mutant glioma than in IDH-WT glioma. The DESI 2HG signal intensities correlated with independently measured 2HG concentrations (R2 = 0.98). In 1 case, an IDH1 R132H–mutant glioma was misdiagnosed as a demyelinating condition by frozen section histology during the intraoperative consultation, and no resection was performed pending the final pathology report. A second craniotomy and tumor resection was performed after the final pathology provided a diagnosis most consistent with an IDH-mutant glioblastoma. During the second craniotomy, high levels of 2HG in the tumor core biopsies were detected.CONCLUSIONSThis study demonstrates the capability to differentiate rapidly between IDH-mutant gliomas and IDH-WT conditions by DESI-MS during tumor resection. DESI-MS analysis of tissue smears is simple and can be easily integrated into the standard intraoperative pathology consultation. This approach may aid in solving differential diagnosis problems associated with low-grade gliomas and could influence intraoperative decisions regarding extent of resection, ultimately improving patient outcome. Research is ongoing to expand the patient cohort, systematically validate the DESI-MS method, and investigate the relationships between 2HG and tumor heterogeneity.

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