NMR&MS Flashcards by Mathilde Brockdorff

What is secondary metabolism?

Secondary metabolism refers to the production of organic compounds by an organism that are not directly involved in its growth, development, or reproduction.

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Secondary metabolites are:

Classified by the building blocks they are biosynthesised from
Structurally diverse and rich in functional groups
Typically associated with a biological active
Very importajt for the medical and industrial usage

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What is the function of HPLC?

To separate a sample of molecules to some affinity, dependent on which column it is on

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What is the function of DAD?

It stands for diode array detector and measures absorbance in the wavelength UV-vis from 190 to 900 nm.

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What is the function of HRMS?

It stands for high-resolution mass spectrometer and its function is to accurately determine the exact mass of molecules and fragments. It helps to elucidate structures by analyzing fragmentation patterns and isotopic distribution.

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What is some of the factors to be aware of during HPLC (high performance liquid chromatography)?

Choice of column
- Eluent
- Gradient (changing) vs isocratic (stable)
- Injection volume
- Sample solvent
  Kinetic matters (temperature flowrate, pressure)

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What is HRMS an acronym for?
Human resource management system

High resolution mass spectrometry

Her royal Majesty Sara

Heavy respons mass spectroscopi

High resolution mass spectrometry

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Which modules are part of a HPLC-DAD system?
- A pump
- A 19T magnet
- An absorbtion chromometer
- A diode array detector
- A HPLC column oven
- A circular dichroism photo detector

A pump, diode array detector, A HPLC column oven

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Name the components of a RP-HPLC-DAD-HRMS

Solvent on the top, pump, autosampler, column oven, DAD at the end and on the side ESI.

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How do you calculate the relative abundance of an isotope peak based on its percentage intensity in a mass spectrum?

(M+n)^′=(M+n)/M∗100
Here M is the heigher peak procentage and (M+n) is the lower peak procentage

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How can M+2 element containing atoms (like Cl, Br, Cu, A) be detected?

(M+2)−(M+1)>1=no M+2 elements
(M+2)−(M+1)<1=M+2 element
This is measured from the m/z values

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Which molecular mass is used in HRMS
Molecular weight (Mw)

Monoisotopic mass (Mi)

Average mass (Mav)

Monoisotopic mass (Mi)

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What is the monoisotopic mass of a compound with the chemical formula C6H12O6

612 + 121.007825 + 6*15.9949
= 180.063

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What is the monoisotopic mass of a compound with the chemical formula C6H11O6Br

612 + 111.007825 + 6*15.9949 + 78.918338
= 257.974

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Which Atom affects the first isotopomer (M+1) the most:
C,H, N, O, Cl,S,Br

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Which Atom(s) affects the Second isotopomer (M+2) the most
C,H, N, O, Cl,S,Br

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Cl, S, Br

True or False: It is possible to estimate the amount of carbon in a molecule by deviding the intensity of the M+2 isotopomer by 1.1.
True or false

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false

Which of the following chemical formula would have isotopic distributions where the most intens isotopomer is NOT the monoisotopic mass of the compound?
C120H200N24O28
C30H48N6O7Br2
C30H49N6O7Br
C30H46N6O7Cl4
C30H47N6O7Cl3
C30H48N6O7Cl2
C30H31N6O7S19
C30H30N6O7S20

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C120H200N24O28 ✅
C30H48N6O7Br2 ✅
C30H49N6O7Br✅
C30H46N6O7Cl4✅
C30H47N6O7Cl3✅
C30H48N6O7Cl2
C30H31N6O7S19
C30H30N6O7S20✅

From the isotopic distribution of a molecule, it was observed the the A+1 isotopomer has a mass at 221.0592 and the A+2 isotopomer has a mass at 222.0561. Use the (A+2)-(A+1) to calculate if the molecule has any A+2 element containing atoms.
also does it contain A+2 elements?

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222.0561 - 221.0592 =0.997
because the value is under 1 it contains A+2 elements

What is the formula for determining the m/z value?

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m/z=(M+n∗X)/n
M:the exact monoisotopic mass of the compound
X:Exact mass of the charge donor
n:number of charges

The intensity of a total ion chromatogram (TIC) is_____________

the sum of all intensities from the spectrum,
the highest intensity from the spectrum,
the intensity of a chosen mass from the spectrum

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the sum of all intensities from the spectrum

Finish the sentence: The intensity of a base peak chromatogram (BPC) is
the sum of all intensities from the spectrum,
the highest inntesity from the spectrum,
the intensity of a chosen mass from the spectrum

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the highest intensity from the spectrum,

Finish the sentence: The intensity of an extracted ion chromatogram (EIC) is_____________
the sum of all intensities from the spectrum,
the highest intensity from the spectrum,
the intensity of a chosen mass from the spectrum

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the intensity of a chosen mass from the spectrum

Write the formula to calculate the mass to charged ratio (m/z) using ESI-MS

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(M+n*X)/n

of a compound with the monoisotopic mass 625.3814 charged with 2 protons

(625.3814 + 2*1.007825)/2= 313.6985

The mass difference between the A and A+1 isotopomer for a single charged ion is approx.

1 Da

The mass difference between the A and A+1 isotopomer for a double charged ion is approx.

0.5 Da

The mass difference between the A and A+1 isotopomer for a 4 charged ion is approx.

0.25 Da

The mass difference between the A and A+1 isotopomer for a triply charged ion is approx.

0.33 Da

Which charge donors are commonly observed in positive ESI: H(+) Ca(2+) NH4(+) Na(+) Au(3+) K(+)

H(+) NH4(+) Na(+) K(+)

What is the intensity of a M+1 isotope?

33.313

What is the nitrogen rule for ESI?

- If a compound contains an even number of nitrogens the m/z value of [M+H]+ will be odd and vice versa when the number is even the m/z will be even. - For compounds containing of C, H,O, N, Si, P, S, Hal

When you want to predict a chemical formula from MS data, it is extremely important to have an accurate measurement. A precission at the third decimal or better is preferred. Why? Exact mass belongs to specific groups of compounds Many compounds share the same nominal mass, but differ slightly on the exact mass You cannot predict chemical formula from MS data

Many compounds share the same nominal mass, but differ slightly on the exact mass

Fill in the blanks: Workflow for predicting chemical formula Identify ______ from the spectrum impurities, the base peak, [M+H]+, M-H2O+H]+

[M+H]+

Fill in the blanks: Workflow for predicting chemical formula Calculate ______

monoisotopic mass

Fill in the blanks: Workflow for predicting chemical formula Estimate the amount of ______

carbon in the molecule

Fill in the blanks: Workflow for predicting chemical formula Use the formula "[A+2]-[A+1] to estimate ______

presence of Cl, Br or S

Fill in the blanks: Workflow for predicting chemical formula If the monoisotopic mass is even, then there is ______

0 or an even number of nitrogen

Fill in the blanks: Workflow for predicting chemical formula If several chemical formula matches your measured monoisotopic mass then you should _________

compare theoretical isotope distributions with the observed

NMR&MS Flashcards

(39 cards)