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I am trying to compare different 31P chemical shift data from a variety of literature sources. However, each of these sources references their data in a different way.

Is there a table somewhere that I could translate 31P shifts taken with DSS to TMP or TSP or phosphoric acid or water?

I've been asking around in the real world and many people are telling me that this data should exist somewhere but neither I nor any of them are able to find out how to convert this data.

Much appreciated, -DC

asked Nov 16 '12 at 10:41

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David Condon

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this problem is not trivial, it is very tricky! There are different ways to do this process and each methods has it's pros and cons!

IUPAC is the best base to go through:

Recommendation 2008: http://pac.iupac.org/publications/pac/pdf/2008/pdf/8001x0059.pdf Recommendation 2001: http://www.iupac.org/publications/pac/2001/pdf/7311x1795.pdf

What kind of type of referencing was done? Internal or external? In former time TMS or DSP are used for the reference, but even TMS has a problem in concentration! (see the recommendations of 2001!) TMS has also a fluctuation by concentration!

Now the system uses the deuterium of the solvent/lock as reference and spread this via the "XSI" system to the different nuclei! You can also take care of the reference of your proton first and inherit this from Proton via the XSI system to other nucleus. But each system has it faults implemented, be aware of these!

I had once a problem with an offset of some ppms between a self made H3PO4 sample with DMSO for locking to a pure H3PO4 sample (sealed by Wilmad). The sealed and deuterium free sample was "save" for me and the system worked fine a couple of years.

Measure all literature values yourself with a modern NMR spectrometer, this will be the best and easiest opportunity.


Uli Haunz


answered Nov 19 '12 at 07:30

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Ulrich Haunz

Hi Uli, There were both internal and external references. I spoke with my adviser about this, and I'm going to re-run some 1H-31P HETCOR on some oligonucleotides as you suggested. Each of the 5 references I found referenced their 31P shifts differently. Ich danke Ihnen! -Dave - David Condon (Nov 20 '12 at 09:28)

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Hi Uli and David,

I'm acquiring data on P-containing samples (10 mM), using 85% H3PO4 as a reference standard in a coaxial insert. I'm new to using this as a standard, and I'm really struggling. Here are my very basic questions:

  1. Do people ever dilute this standard? It's outrageously high in signal, leading to baseline oddities that may impact my peaks, and some satellites indeed do. The fact that everyone says (explicitly) in their papers 'referenced to 85% H3PO4' makes me think not, but it's just too concentrated for my liking. I can't find any literature as to dilution-dependent shifts -- I'm trying to detect ~0.1 ppm shifts, so it actually matters.

  2. Most of the time, the phosphoric acid has an offset of 0.47 ppm -- should I just check this value every so often, omit the 85% H3PO4 coaxial insert from my sample, and adjust my spectra accordingly?

Sorry for the basic questions -- these experiments are sufficiently time-intensive. Thanks for any help that you can provide.

Thanks, Rachel


answered Mar 24 '13 at 14:56

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Rachel Smith

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