Calculating mass from a NMR spectrum

In summary: Expert Summarizer In summary, to calculate the mass of DMSO from an NMR spectrum, the mass fraction of DMSO in the sample can be determined by dividing the area of DMSO by the total area of the spectrum and multiplying it by a correction factor. The mass of DMSO can then be calculated by multiplying the mass fraction by the total number of protons in the sample and the average molecular mass per proton. The correction factor may vary depending on the instrument and sample concentration.
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I'm trying to calculate the mass of a chemical (DMSO) and from a NMR spectrum of water and DMSO. I have the value of the total area under the spectrum and I have the value of the total area corrosponding to the DMSO peak and the total area corrosponding to water.

I know that the total area of the spectrum is proportional to the number of protons in the sample and DMSO has a 6 protons per molecular mass of 78.

I have gone some way to calculating it by saying:

Mass Fraction= (Area of DMSO/Area of total Spectrum) *Correction factor (This is what is needed to convert to mass but unsure what to multiply it by)

Any help would be much appreciate!:smile:
 
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  • #2


Hello,

Thank you for reaching out for help with your calculation. I can provide some guidance on how to calculate the mass of DMSO from the NMR spectrum data you have.

First, it is important to note that the total area under the spectrum is proportional to the number of protons in the sample. Therefore, to calculate the mass of DMSO, we need to determine the mass fraction of DMSO in the sample.

To do this, we can use the following formula:

Mass Fraction = (Area of DMSO / Area of total spectrum) * Correction factor

The correction factor you mentioned is needed to convert the area of the spectrum to mass. This correction factor will depend on the instrument used for the NMR analysis and the concentration of the sample. It is usually provided by the instrument manufacturer or can be determined through calibration experiments.

Once you have the mass fraction of DMSO, you can then calculate the mass of DMSO by multiplying it by the total mass of the sample. The total mass of the sample can be determined by multiplying the total number of protons in the sample by the average molecular mass per proton (1.00783 amu).

So, the final formula to calculate the mass of DMSO would be:

Mass of DMSO = Mass Fraction * Total number of protons * Average molecular mass per proton

I hope this helps you with your calculation. If you have any further questions or need clarification, please don't hesitate to ask.
 

What is NMR and how is it used?

NMR (nuclear magnetic resonance) is a scientific technique used to analyze the structure and composition of molecules. It involves applying a strong magnetic field to a sample and recording the resulting signals to create a spectrum. This spectrum can then be used to determine the types and quantities of atoms present in a sample.

How do you calculate mass from an NMR spectrum?

To calculate the mass of a molecule from an NMR spectrum, you need to know the chemical shift values and the integration values of the peaks. The chemical shift values can be used to identify the types of atoms present, and the integration values can be used to determine the relative number of each type of atom. From there, you can use the atomic masses of each element to calculate the total mass of the molecule.

What are chemical shifts and how do they affect mass calculation?

Chemical shifts refer to the position of a peak in an NMR spectrum, which is influenced by the chemical environment of the atom. Different chemical environments can cause a peak to shift to a different location on the spectrum. These shifts can help identify the types of atoms present in a molecule, which is essential for calculating its mass.

What is integration and why is it important in mass calculation?

Integration is a measurement of the relative intensity of a peak in an NMR spectrum, which is directly proportional to the number of nuclei that produce that peak. This information is crucial for calculating the mass of a molecule because it allows you to determine the relative number of each type of atom present.

How accurate is mass calculation from an NMR spectrum?

The accuracy of mass calculation from an NMR spectrum depends on various factors such as the quality of the spectrum, the type of molecule being analyzed, and the precision of the instrumentation. However, in general, mass calculations from NMR spectra are considered to be highly accurate and reliable.

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