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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Are alkoxy radicals more stable than primary radicals?

My question has two parts: First: Generally speaking, are alkoxy or other heteroatom radicals more stable than primary carbon radicals? Second: Is the second MS fragmentation pathway in my diagram ...
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400 views

What are compounds with the same mass called?

It may be that the answer is just "no" and that's why I can't find it, but is there any common name for compounds with the same mass? I'm thinking in the context of mass spectrometry where these ...
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41 views

GCMS Peak Identification: Online or Open Source / Free Programs?

Suppose I have a GCMS peak graph for a component, what are possible options to figure out what the molecule may be? Any tips about good software that will do this? I do know that for many compounds ...
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710 views

Can we recycle garbage with the principles of mass spectrometry?

'Mass Spectrometry (MS) is an analytical technique that sorts ions based on their mass (or "weight"). Mass spectrometry is used for many chemical analyses, ranging from the analysis of a complex ...
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61 views

Fragmentations and rearrangements in n-(4-alkyl phenyl) alkanoic acids in mass spectrometry

I have this example exam question for which I don't have the answer. I have been working on it the whole morning but I can't figure it out. The question suggests three molecules, only one of which ...
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42 views

Minimum resolution to acquire exact mass on a spectra from m/z peak

I'm having a little difficulty with finding what the minimum resolution required to obtain the exact mass of a 400 m/z peak on a mass spectrometry spectra is. I would appreciate any help. Thank you in ...
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46 views

Assigning Mass Spectrum of $\ce{(NPCl2)3}$

I'm trying to assign the mass spectrum of the heterocyclic compound $\ce{(NPCl2)3}$ The mass spectrum is as follows: My annotations show that I think the molecular ion is the peak at 346.9 m/z and ...
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30 views

What causes differences in limits of detection?

I'm wondering what causes the limits of detection (LOD) to vary between different compounds, when calculated from the data obtained from one sample. I've analyzed a 0,1 µg/ml sample, containing ...
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41 views

Why is the molecular peak not observed in the spectrum of 2,2-dimethylbutane?

Why is its MW not on the mass spectrum? I can tell that a $\ce{-CH3}$ group is removed just by the math, but I do not know the reason why. The MW is 86 and I know it has to do with fragmentation.
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41 views

Pentabromophenol Mass Spectrum

I am working on analyzing the mass spectrum of pentabromophenol but am struggling to determine the fragment at 60 m/z. It could possibly be 5 carbons however that is too much positive charge to exist ...
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156 views

Why can't carbon and nitrogen be detected in ICP-MS and ICP-OES techniques?

Why can't carbon and nitrogen be detected in ICP-MS and ICP-OES techniques? My book says this technique is efficient for detecting multiple elements, with exception of halogens and carbon. I found ...
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78 views

Continuous flow mass spectrometer for isotope analysis

If i took thousands of discrete samples of mineral fragments in a field study using a specialized drill, what mass-spectrometry techniques/equipment would allow me to analyse the samples as fast as ...
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100 views

why do we denature proteins before mass spectroscopy?

I'm learning about mass spectroscopy in particular the use of it in analyzing protein structure. they said we have to use trypsinolysis to cut the protein to segments, but why does the protein have to ...
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63 views

What is the difference between TIC and TICC?

I have picked up a textbook on mass spectrometry, and I am finding it did not clearly distinguish between total ion chromatogram (TIC) and total ion current chromatogram (TICC) in the section (1.3 Ion ...
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98 views

How mass spec formate and acetate adducts masses are calculated?

If I look at any tables or calculators, I find that negative ion formate adduct has a monoisotopic mass of +44.9982 units. If I try to calculate myself, I get ...
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39 views

Mass Spec - What could a loss of 28amu as the first fragmentation be?

I guess 28 could be CO, C2H4 or N2. However I can't work out a mechanism by which CO could be the first fragmentation of any common organic compound. It seems like a diazonium salt could lose N2 as ...
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27 views

How to control the purity and quality of fatty acids or their CoA thioesters?

Background: We are looking into getting a series of cis-mono-unsaturated very-long-chain (C20-C32) fatty acids (with different, specific double-bond positions) — and/or the corresponding acyl-Coenzyme ...
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116 views

Predicting isotope patterns in mass spectrometry

Can anyone help me with the question “Imagine you have a mixture of hydrogen-1, hydrogen-2 and hydrogen-3. (hydrogen, deuterium and tritium) present as diatomic molecules and that the numbers of the ...
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110 views

What is the mechanism for electrospray ionization?

I've been asked to Descibe the ionization mechanism used in electrospray ionization I know that this is a desorption ionization source, which uses a high electrical field as the ionizing ...
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116 views

Relative atomic mass

Is it possible for an element to have a calculated relative atomic mass that is higher than the relative isotopic mass of its most massive component isotope? The equation is: ...
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429 views

Mass Spectrum and Molecular Ion peaks

If a molecule contains four chlorine atoms, how many molecular ion peaks will this compound show in its mass spectrum?
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65 views

Tandem mass spectrometry: a1 and immonium ions

In tandem mass spectrometry of proteins one will usually end up with a mix of $b$ and $y$ fragments but also $a$ fragments and immonium fragments. My problem is that wouldn't an $a_1$ ion be the exact ...
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2answers
355 views

Fragmentation of phenyl radical cations in mass spectrometry

What are the main fragmentation pathways and products of a phenyl radical cation in mass spectrometry ? I notice sometimes that there's a m/z = 51 peak after the m/z = 77 for phenyl radical cation; I ...
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Finding identities of diatomics from Spectroscopy and Mass Spec Data

Let's say I have a sample of 2 (assumingly different) diatomics A and B. Through Spectroscopy I found the data below: For molecule A: $$B ̃=2.17690\space cm^{−1}$$ $$D ̃=4.79000×10^{-5} cm^{−1}$$ ...
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728 views

Why would the 2+ molecular ion of butane have a mass spectrum peak at 29?

Question 7 of Edexcel's June 2014 Unit 2 exam paper reads: In a mass spectrum of butane, C4H10, where would a peak be seen for the molecular ion if it had a charge of 2+? The answer is 29. My ...
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31 views

What is the significance of an organic compound's M peak?

Background On the topic of identifying an organic compounds using peaks generated in Mass Spectrometry, a rule of thumb expressed in the UK educational textbook, CGP, is that that "the M peak is the ...
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147 views

How were the absolute masses of atoms calculated before the mass spectrometers?

I understand that true (non-relative) masses of atoms are calculated with a mass spectrometer. using this relationship: Centripetal Force = Force due to magnetic field(B) But I was wondering how ...
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454 views

What is 'Retention period' in chromatography and what is its importance?

I heard people quite often speak about retention time/retention period in Chromatography and Mass Spectrometry. I see somewhere that it is the time duration between the injection time and the target ...
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85 views

In a mass spectrum, how can the sum of relative abundances be greater than 100?

I apologise if this seems a very simple question, and also if I am overlooking something that is very simple. For part of my A Level course, we have to be able to interpret mass spectrometer readings ...
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137 views

GC-MS unexpected peaks during 1-octanol quantification

Note: This experiment was performed as part of a teaching lab experiment which has concluded, so I would not be able to alter any experimental conditions. I was also unable to modify any of the ...
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69 views

Is is possible to do mass spectrometry without coupled liquid chromatography?

It's possible to identify a solution with several compounds* without the coupled liquid chromatography (LC) before to isolate the compounds? On the university where I study, the LC is broken, so all ...
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1answer
88 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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127 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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206 views

How does bombarding a molecule with electrons cause ionization?

I am a chemistry student, and my current are of study is mass spectrometry. In the ionization process, atoms are bombarded with electrons, but how does this work? I assume the flow of electrons ...
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168 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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452 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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116 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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586 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
134 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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1k 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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6k 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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1answer
3k 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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79 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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361 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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2answers
532 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
711 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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271 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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738 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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2answers
623 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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2k 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 ...