RMS and Standard Deviation in S/N calculation

[Ken]

Hi there. I have a question in regards to the signal to noise calculation.

I came acrosss signal to noise calculation based on RMS ; where else some other calculations were based on the signal to noise using 3 std deviation ( in accordance to EU std).

May I know what is the difference in using either one of the signal to noise calculation based on RMS or standard deviation?

Thanks a lot.

[Dan]

Ken,

There have been a number of discussions about noise measurements in this forum.

Here is an example: http://www.sepsci.com/chromforum/viewtopic.php?t=6245

If you search the forum, you will find more.

You can also check the ICH guideline for method validation: http://www.ich.org/LOB/media/MEDIA417.pdf
Look in Section II.6 Detection Limit.

An important aspect of determining the noise is that you define the manner in which you are determining the noise and that you be consistent in the application of the technique that you choose. As you noted, one technique is to use the RMS measurement and another is the standard deviation.

Regards,
Dan