# Tag Info

Accepted

### Why is the probability for the signal at 160 in the bromine mass spectrum twice as high as for the signals at 158 and 162?

All possible arrangements of $\ce{Br2}$ molecule: $\displaystyle 79 + 79 = 158$ $\displaystyle \color{red}{79 + 81} = 160$ $\displaystyle \color{red}{81 + 79} = 160$ $\displaystyle 81 + 81 = 162$ ...
Accepted

### Why is a very small peak with larger m/z not considered to be the molecular ion?

Without knowing more details, it is hard to guess, but at this $m/z$, it seems likely that the peak is the result of one $^{12}\ce{C}$ being substituted by one $^{13}\ce{C}$. It is more useful to ...
Accepted

### Can we recycle garbage with the principles of mass spectrometry?

Yes it is possible, but is very expensive and would be orders of magnitude more costly than what people are willing to pay for recycled materials. Let me give two data points to explain why it is ...

### Which unit should I use for m/z?

TL;DR: According to current IUPAC recommendations, $m/z$ is an abbreviation for a dimensionless quantity. Use of thompson unit is indeed currently discouraged. There is an overview provided in ...

### Why is a very small peak with larger m/z not considered to be the molecular ion?

The peak at $m/z = 59$ with lower intensity in respect to the one at $m / z =58$ (the molecular ion) is not overseen. Mass spectroscopy is capable to deliver information about the isotopic ...

### Why are isotopes an issue in reading mass spectra?

Here is the "periodic table for biomolecules" (leaving out hydrogen, please ignore silicon): The pie chart shows the isotope distribution. Of the elements C, N O, P, S and H, sulfur has the highest ...

### How do I figure out how many hydrogens my compound actually has using a mass and NMR spectrum?

Being an NMR fan myself I would inspect that NMR spectrum: The integrals suggest you have 11 $\ce{^1H}$ or a multiple thereof (the number under each peak is the normalized integral, which is ...

### How do I figure out how many hydrogens my compound actually has using a mass and NMR spectrum?

I would probably also use the method Buck has suggested, but let’s say the NMR broke down or somebody is measuring a $\ce{^13C}$ of $\pu{2.5mg}$ meaning it will be blocked until tomorrow; in this case,...
Accepted

### Behavior of Natural Abundance and Mass Spec Ratios

You are probably mixing natural abundance (NA) and relative abundance (RA). In mass spectrometry RA is a more valuable parameter as it can be directly obtained as the $y$-coordinate of a plotted mass ...
Accepted

Accepted

### Why do dihaloalkanes lose both halogen atoms during mass spectrometry?

It isn't just both bromine atoms that are lost, although that might be expected in mass spec given the relative weakness of the carbon-bromine bond. You also lose a hydrogen atom. And that is key. ...
This type of ionization is known as electron ionization (there are many types of ionization methods used for MS). One possible reaction for EI is: $$\ce{M +e- ->M^{•+} +2e-}$$ source If the ...