I have a DEPT analysis problem.

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In summary, DEPT spectra is used to analyze an organic sample and has 4 spectras for protonated carbon: CH, CH2, and CH3. Although the CH and CH2 spectras should be different, they appear to be the same. To separate the peaks, the tip angle of the final 1H pulse needs to be varied and an experiment needs to be performed to determine the 90 degree pulse width for the CH proton. The proton decoupler should also not be continuously on while acquiring the FID.
  • #1
hyildirim
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I have taken a DEPT spectrum of an organic sample.
It has 4 spectras that are all protonated carbon, CH, CH2 and CH3.
They especially CH,CH2, and CH3 spectras should be different but CH and CH2 spectras are same.
What can I do to separate CH and CH2 peaks? Could you give me any suggestion?
 
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  • #3
You will need to perform an experiment to determine the 90 degree pulse width for the CH proton and from that calculate the 45 degree pulse width. That needs to be fairly accurate and you need to put in a pulse delay 10X the longest decay constant for the slowest recovering proton... another experiment for that. Be sure the proton decoupler is not on continuously as well while you acquire the FID.
 
  • #4
Thanks for your helps..
best regards
 
  • #5


Based on the information provided, it seems that there may be an issue with the DEPT analysis of the organic sample. It is unusual for the CH and CH2 spectra to be the same, as they should have distinct peaks due to their different chemical environments.

To troubleshoot this issue, I would suggest checking the instrument settings and parameters used for the DEPT analysis. It is possible that the acquisition parameters, such as the pulse sequence or power levels, may need to be adjusted to properly differentiate between the CH and CH2 peaks.

Additionally, it may be helpful to repeat the DEPT analysis using a different instrument or technique, such as 1D proton NMR or 2D NMR, to ensure the accuracy of the results.

In order to provide more specific suggestions, it would be helpful to know more details about the organic sample and the experimental setup. It may also be beneficial to consult with a colleague or expert in NMR analysis for further assistance.
 

What is a DEPT analysis?

DEPT analysis is a type of nuclear magnetic resonance (NMR) spectroscopy used to determine the number and type of hydrogen atoms in a molecule. DEPT stands for Distortionless Enhancement by Polarization Transfer and allows for the differentiation of different types of hydrogen atoms (CH, CH2, and CH3) in a molecule.

Why is my DEPT analysis not working?

There could be several reasons why your DEPT analysis is not working. Some common issues include incorrect instrument settings, sample preparation errors, or problems with the instrument itself. It is important to troubleshoot and check all possible factors to determine the cause of the problem.

How can I improve the quality of my DEPT spectrum?

To improve the quality of your DEPT spectrum, you can try adjusting the instrument settings, optimizing the sample preparation, or using a different solvent or concentration. Additionally, proper shimming and pulse calibration can also improve the quality of the spectrum.

What are some common errors in DEPT analysis?

Some common errors in DEPT analysis include baseline distortions, signal overlap, and insufficient signal intensity. These errors can be caused by issues with the instrument, sample preparation, or data processing. It is important to carefully review the spectrum and troubleshoot to correct any errors.

Can I use DEPT analysis for all types of molecules?

DEPT analysis is most commonly used for organic molecules with at least one hydrogen atom. However, it may not be suitable for all types of molecules, such as inorganic compounds or molecules with a low hydrogen content. It is important to consult with an expert or literature to determine the appropriateness of using DEPT analysis for your specific molecule.

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