AMMRL: 1H and 13C chemical shifts of DSS at different temperatures

From: Zhang, Weixing <Weixing.Zhang_at_STJUDE.ORG>
Date: Mon, 4 May 2020 17:02:02 +0000

Hello All,

The following ratio has been recommended to reference 13C chemical shift indirectly for protein NMR.
13C-1H (DSS) 0.251449530

I measured 1H and 13C chemical shifts of DSS at different temperatures (283 K to 303 K) using the sucrose water suppression sample. 1H chemical shift of DSS changes 0.0112 ppm/K and 13C chemical shift changes 0.0155 ppm/K. As a result, the 13C/1H frequency ratio also changes with temperature.
Based on my measurement, the new ratio at temperature T relative to 288 K is
New ratio at temperature T = 0.25144952941 x [1 + 4.3E-9 x (T - 288)].
Relative to 298 K is
New ratio at temperature T = 0.25144954022 x [1 + 4.3E-9 x (T - 298)].

If the chemical shift change of DSS is caused by lock frequency change, why do the 1H and 13C chemical shifts of DSS change by different amount?

Thanks,
Weixing
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Received on Mon May 04 2020 - 07:02:14 MST