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Hello All

Does anyone have any ideas on what might give a phosphorus signal at negative 74 ppm (cf phosphoric acid)? There's a very small signal in many of my 31P spectra at -74 ppm. It's not a spectrometer artefact and it it present in samples prepared by different people on- and off-site using different tubes and different sources of solvents. The samples are chemically variable too, alkyl/aryl-phosphines in organic solvents, phosphates in water but there's this little curiousity at -74 ppm.


asked Nov 12 '13 at 01:56

Craig's gravatar image


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I need more information and also some pictures, ... which spectrometer, Bruker,Varian/Agilent, JEOL, ... have you changed the middle of the spectra, ... moving tof or O1? Or have you changed the spectral window (SW)??? Is the signal/peak phaseable?

Thanks for more information



answered Nov 12 '13 at 07:56

Ulrich%20Haunz's gravatar image

Ulrich Haunz

Hello Uli. It appears that the signal is an artefact after all. To answer your questions - Bruker, moved O1, changed SW, out-of-phase. It seems to appear only with certain combinations of O1 and SW and a genuine 31P signal. I'll send pictures by email. - Craig (Nov 19 '13 at 05:10)

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Hi Craig,

Do you see it if you run a spectrum of an empty tube?



answered Nov 14 '13 at 01:56

Pete%20Gierth's gravatar image

Pete Gierth

Hello Pete. On a blank of tube + CDCl3, there is no signal. - Craig (Nov 19 '13 at 05:11)

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Asked: Nov 12 '13 at 01:56

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Last updated: Nov 19 '13 at 05:11

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