Signal to noise in custom field
Hi all,
I'm trying to do Signal to noise calculation in a custom field. We have peaks in our blank injection and because of that we cannot use the built in USP S/N calculation. I have tried used this tutorial to set this up:
Processing methods - Calculate signal-to-noise ratio using a specified segment from the blank injection - wkb260922 - Waters
It does work, but only for known peaks, not for unknown peaks. In the blank injection Signal to noise is calculated for unknown peaks, but not in sample injections. The custom field is setup with peak type: All, and in the processing method, Calculate Suitability Results for Unknown Peaks are selected in the Suitability tab.
How do I get this to work for unknown peaks?
Thanks in advance for your help
I'm trying to do Signal to noise calculation in a custom field. We have peaks in our blank injection and because of that we cannot use the built in USP S/N calculation. I have tried used this tutorial to set this up:
Processing methods - Calculate signal-to-noise ratio using a specified segment from the blank injection - wkb260922 - Waters
It does work, but only for known peaks, not for unknown peaks. In the blank injection Signal to noise is calculated for unknown peaks, but not in sample injections. The custom field is setup with peak type: All, and in the processing method, Calculate Suitability Results for Unknown Peaks are selected in the Suitability tab.
How do I get this to work for unknown peaks?
Thanks in advance for your help
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Answers
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If you google the following:Waters Empower USP Chapter <621> Frequently AskedQuestions: Calculating Signal-to-Noise
You will get an article about FAQs on questions and answers to do with using the blank and custom fields to solve this issue. Question 4 deals specifically with using a different section of the blank injection to calculate signal to noise and you need a custom field to achieve this. The article shows you the formula for this and how to use it, plus it works on all peaks, known and unknown.0 -
Thank you for the answer.
The article you refer to and the one I linked to are the two articles I have been using to set this up. This is the formula I have in the Custom field, which I believe is the exact formula from the article you refer to:
2*(Height-(0.5*Blk.1.(Peak to Peak Noise/Scale to µV)))/Blk.1.(Peak to Peak Noise/Scale to µV)
From what you are saying, it should work on unknown peaks? I must be doing something wrong then. Do you have any idea what might be wrong? Is there any settings, or something else, that may affect this?
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That's odd because I've been using that exact custom field for a few months now and it works fine for known and unknown peaks. Make sure your custom field is set to All sample types and All peak types.0
