Tagged Questions

Mass spectrometry (MS) is an analytical technique which takes advantage of the mass-to-charge ratio of gas-phase ions in order to elucidate the composition of a sample.

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55 views

How to find the mass spectrum of Cl₃⁺?

The setting of this problem is on the moon of Jupiter: Io. Given that Chlorine exists in two isotopes: $\ce{{}^{35}_{17}Cl}~(33.3\%)$ and $\ce{{}^{37}_{17}Cl}~(66.7\%)$, what is the mass spectrum ...
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Modeling fragmentation patterns from electron impact (EI) ionization?

Are there any good studies or references for interpreting mass fragments from EI-MS? Anything ranging from empirical studies to mechanistic modeling. While the fragmentation is severe, there still ...
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1answer
48 views

Mass Spectroscopy peak assignments in but-3-en-1-ol

i have the mass spectrum for the molecule but-3-en-1-ol. The Mr of this is 72 There are four peaks that are labelled which I have to name the species responsible for forming that peak. The peaks ...
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1answer
51 views

How does bombarding a molecule with electrons cause ionization?

I am a chemistry student and am currently studying Mass spectrometry. In the ionization process atoms are bombarded with electrons to ionize them, but how does this work? I assume the electrons ...
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2answers
81 views

What is the highest relative abundance for diatomic bromine?

I was introduced to this thing today, and saw a graph showing the detection of ions with different relative abundances. Just as an example here, $\ce{Br2}$ is shown a detection chart. And at ...
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62 views

How can I reverse engineer a commercial cleaning solution's “other ingredients”?

I have a commercial lens cleaning solution. The manufacturer of the solution claims it is not only distilled water and that the formula is confidential. I suspected it was only or mostly distilled ...
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59 views

What is the process involved in performing a mass spectrometry experiment?

I have heard that mass spectrometry is very time consuming: why is this? What is the process involved in performing a mass spectrometry experiment? What steps are the most time consuming?
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156 views

Where does the characteristic peak for phtalic acid diethyl ester at m/z 149 originate?

Which fragmentation is possible at this m/z value for phthalic acid diethyl ester? I tried McLafferty but it didn't solve my problem.
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1answer
50 views

ESI & MALDI Mass Spectrometry: particle mass vs. measurement error

For MALDI or ESI mass spectrometry of large macromolecules (e.g. in the $\approx 100$ kDa to $\approx 10 - 100$ MDa mass range), I've always how measurement error scales with particle mass. Not ...
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3answers
123 views

Could someone please explain the difference between m/z and m/e in mass spectroscopy

The definition: The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio ...
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1answer
192 views

Difference between an absorbance, emission, and excitation spectrum for uv-visible spectroscopy

The exam paper answer is 500, because we need the wavelength of "maximum absorbance." But this graph shows two curves, and the absorbance curve is omitted. But what is the difference between an ...
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311 views

How to calculate m/e value for the base peak in mass spectroscopy?

My working out: Propan-1-ol : CH3CH2CH2OH This can be broken up into: CH3 + CH2CH2OH CH3CH2 + CH2OH CH3CH2CH2 + OH Base peak = most abundant fragment formed (highest peak) How do i know which ...
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1answer
28 views

Calculate accelerating voltage required to separate two particles in a magnetic sector analyser

So, in mass spectrometry we have the following equation to describe a magnetic sector analyser, $$\frac{m}{z}=\frac{B^2r^2e}{2V}.$$ Lets say that I have two particles with different mass/charge ...
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92 views

1H-NMR and deducing structures

here is the data booklet we must refer too: Here is the exam paper solution: I dont understand how they conclude this. Peak areas and the chemical shifts seem to be different for me. For ...
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23 views

ESI MS/MS: Fragments are different in LC-Water and Sample

I'm no chemist and maybe someone of you has an explanation? I'm running a HPLC ESI MS/MS triple quadrupol with the solvents TDFHA and Acetonitril and reverse phase column. The conditions are not ...
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113 views

How does mass spectroscopy of nicotine work?

Take this nicotine molecule: And this mass spectrum: I'm not sure how to explain all the peaks. This might explain the peak at 42: But can this peek als be explained by something else in ...
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1answer
172 views

What's the difference between mass spectrometry, mass spectroscopy, and mass spectrography?

It seems that the terms mass spectrometry, mass spectroscopy, and mass spectrography are mostly used like synonyms. Is this correct? Or is there a difference?
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1answer
121 views

Looking for raw interferogram data / raw FID data from FT-IR / FT-NIR / FT-NMR

I'm trying to get my hands on some raw interferogram data / raw FID data from an FT-IR / FT-NIR / FT-NMR so I can run some tests using FFT with it (it needs to be real data). Here's a picture below of ...
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1answer
274 views

Mass spectrometry: trouble with acetic acid fragmentation

I'm trying to do compound optimization for acetic acid on a EI-MS. Later on it would be also run via HPLC to the MS. But I do only get fragments of 53/54 and 32. Also I need a high concentration to ...
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231 views

Interpretation of the following mass spectrum

I'm given the above spectrum. $M^+ = 102$, probably $\ce{C_6H_14O}$ or $\ce{C_5H_10O_2}$. I'm thinking of ethyl propionate. (that picture also shows the fragments I expect). I can account for the ...
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1answer
139 views

How to interpret a MALDI mass spectrum?

I have some questions regarding how to read a MALDI mass spectrum in a paper. I am a biologist by training, so I would like some analytical chemists to help me out. The researchers ran a western ...
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38 views

Mass Spectrometry configurations

If MALDI is used as an ionization method, then TOF as an analyzer is suitable since the MALDI creates singly charged ions which have high m/z ratio and only TOF can analyze that ions, and multichannel ...
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1answer
237 views

What is the substituent on this benzaldehyde? (MS attached)

I have no clue what the substituent may be. The molar mass of the unsubstituted benzaldehyde is 105g/mol (subtracting one H, where the substituent will be). So the substituent is around 30-33g/mol. ...
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1answer
166 views

Understanding how mass spectroscopy works

I’m trying to get a deeper understanding of how mass spectroscopy works. Most tutorials and textbooks I’ve encountered omit certain details about the process and I’m hoping someone out there who ...
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2answers
835 views

How long does it take to run a MS/MS experiment

I am not planning to do these types of experiments but I would like to know the order of magnitude of the time it takes to run an LC-MS/MS experiment. Let's assume that I have the sample prep ...
9
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1answer
4k views

Resolution in Mass Spectrometry

I have been reading about resolution in Mass Spectrometry and there are a few things I do not understand. The resolving power is determined by m/(m2-m1) at full width half height of a peak. The ...
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1answer
602 views

What do typical results from inductively coupled plasma mass spectrometry (ICP-MS) look like, and how do I interpret them?

I have a degree in chemical engineering and remember having seen a inductively coupled plasma mass spectrometer (ICP-MS) during the laboratory part of a chemistry course I took while at university, ...
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2k views

Gas chromatography/mass spectrometry: Can I use peak ratios and molecular mass to derive quantity?

Can derive the quantity of a substance from a GC/MS report if I know: the ratio to another substance in the data, the quantity of that second substance, and the molecular mass of both substances. ...