Question

Hi all, I want to calculate error in ppm from my Hsqc data. My spectrometer yields X1axis, Y1Axis, DX1, DY1, X1ppm, and Y1ppm. I know that DX1 & DY1 are errors in Hz for X1axis & Y1Axis. But how do you convert that to ppm if i'm working in 900 MHz and Sw of 12626.263 HZ. Thank you

Answer 1

Hi,
I don't know which dimension (X1 or Y1) corresponds to 1H and which one to heteronucleus (15N, 13C, etc.), so basically:

$https://upload.wikimedia.org/math/e/6/6/e66a8e2882f85f67d64b6627e08757b6.png$

https://en.wikipedia.org/wiki/Chemical_shift

In case of 1H dimension:

1 ppm = 900 Hz (for a magnet with magnetic flux density B = 21T; magnet 900MHz)

To calculate heteronucleus you need it's resonance frequency. This kind of data can be found for example in UIPAC data:
http://www.iupac.org/publications/pac/2001/pdf/7311x1795.pdf

13C dimension:

1 ppm = 226,30 Hz (for a magnet B = 21T; magnet 900MHz)

15N dimension:

1 ppm = 91,23 Hz (for a magnet B = 21T; magnet 900MHz)

I hope my answer will be useful for you. By the way, you have quite nice spectrometer there. It's probably for protein multidimensional measurments? Hah, in case of my compounds CSA is strongly visible at 600MHz apparatus,so at 900MHz it would be certainly quite a mess.

Best regards,
Arek

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