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Thursday, December 6, 2007

Removing t1 Noise from Heteronuclear Correlation Data

Heteronuclear correlation data can often contain vertical stripes of noise, called t1 noise. This noise can be reduced by taking the projection a group of rows containing no signals (only noise) and subtracting the projection from every row of the data. This is illustrated below for an HMQC spectrum. The spectrum on the right is the data after Fourier transformation. The data contains a considerable amount of t1 noise. All of the rows highlighted in yellow, containing only noise, were used to prepare a projection. The projection was subtracted from every row of the data. The result is the spectrum on the right. The t1 noise is much reduced.

2 comments:

Zhangzf said...

Glenn,
How to get the rows of noise?
Is there any t1 noise from homonuclear correlation data?

Glenn Facey said...

Zhangzf,

Thank you for your comment.

The way in which the columns of noise are retrieved, summed, stored and then finally subtracted from the dataset sepends on the software used.

There can indeed be T1 noise in homonuclear correlation data. In these experiments however it is more common to remove the noise by symmetrizing the data about the diagonal.

Glenn