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MS spectrum questions

MS spectrum questions - Mass Spectrometry Forum

MS spectrum questions - Discuss and post questions about LC-MS, Q-STAR, MALDI-TOF, and other Mass Spectrometry Questions in the Mass Spec Forum.


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Old 05-30-2010, 06:48 PM
Pipette Filler
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Default MS spectrum questions



Hello,

I have some MS specrtum questions, which I could not figure out.
Could you please help?

Attached are the spectra.

1- The molecular formula is CH7HBr. Two questions:
What is the 65 ion?
Can this MS spectrum tell me whether it is Bromomethyl benzene or 1 Bromo-3-methyl benzene? what I'm not sure about is: Is there one substituent which is methylbromide, or two substituent in two positions- one is a bromide and the other is a methyl?
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Old 05-30-2010, 06:51 PM
Pipette Filler
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Default MS spectrum questions- II

2nd question-
The molecula formula of the attached spectrum is C9H10O.

I figured out it is some kind of an aromatic ring with a ketone. But can this specrum say whether the substituent is a three carbon ketone (it would be Benzyl methyl ketone) or two substituents- a two carbon ketone and a methyl (that is 1-(4-methylphenyl)- Ethanone)?

Can the MS diffrentiate between the two?

Many thanks!
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Old 05-30-2010, 06:53 PM
Pipette Filler
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Default MS spectrum questions III

The third spectrum is attached, for C5H8O2.
With this one I have the biggest problem. I know it's neither an alcohol, nor a carboxylic acid. I analyzed the fragments, which gave me several options, which I don't know how to eliminate:
1. dialdehyle, which would be glutaraldehyde
2. diketone- either 2,3-Pentanedione or Acetylacetone
3. An ester- Acetic acid, 2-propenyl ester or Propanoic acid, ethenyl ester.

Another thing is that I don't know how to approach the 57 and 58 fragments- what are they? what do they hint for?

Many thanks again
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