I recently requested a ESI-MS analysis of 2,3,5-tribromothiophene and got this spectrum:

MS analysis of 2,3,5-tribromothiophene

These are the analysis conditions:

  • Detector: ESI(+)
  • Source Tem: 150
  • Capillary voltage: 1.5 kV
  • Cone Voltage: 20 V
  • Mass range: 200 - 1000
  • Flow: 0.2 mL/min
  • mobile phase: 0.1% formic acid:acetonitrile (50:50)

The sample was dissolved in methanol. Below is the spectrum of methanol:

MS spectrum of methanol

The molecular weight of 2,3,5-tribromothiophene is 320.83 g/mol. But why does the base peak occur at m/z=382 and what are higher m/z peaks like m/z=423 and 740? I can't interpret the result at all.

  • 2
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    – orthocresol
    Aug 9, 2021 at 10:03


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