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By Kristina on Friday, July 30, 2004 - 08:13 am:
I would like to get some comment on the correctness of the way I use for determination of noise for signal-to-noise ratio in an HPLC method. I work in the regulated environment and automized determination of noise is preferable and more convenient for QC labs. I´ve made a comparison-I´ve measured the peak height of noise:1) manually by ruler ("as in the old days")and 2)automatically by choosing the peak-to-peak noise parameter in the Millenium 32 software. I considered both values being comparable. My concern is: what is the correct way to calculate S/N? The peak-to-peak noise is then used in the formula according to Pharm Eur (EP) with some adjustment: S/N=2H/h, where h equals peak-to-peak noise of the blank during 1 min at the place where the component would be found and H is the component´s peak height. The other formula used to calculate S/N by some people is just S/N=H/h, where h is noise in the blank measured manually and H is the component´s height measured by Mil32. I guess there is a discrepancy between these two formulas (a factor of 2?). Could some experts in this field explain what is more correct to use?
Thanks a lot.
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By anila on Friday, July 30, 2004 - 08:53 pm:
Then what is the difference between 'Baseline noise' and 'peak to peak noise' fields in mil32.
For getting the 'p2p noise' , we need to select the 'detector noise and drift' tab, where as for base line noise, we need to select the "suitability" tab.
Which noise value has to be used in S/N ratio calculation.
can anybody please clarify me.
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By A on Saturday, July 31, 2004 - 06:51 am:
I use average peak to peak noise. I use this because if I zoom into the baseline and actually measure the noise (with a ruler), the values usually compare quite nicely. You get to define, in your SOP, which is the right one for your assay.
Peak-to-peak noise is defined as the sum of the maximum and minimum differences between each data point and the least-squares line.
Average peak to peak noise is the above averaged over the user defined time (often 30 seconds) during the define mesurement section (I like to use 2 minutes if I can).
Baseline noise is the amount of noise calculated for the region between the user-specified start and end times in the chromatogram
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By anila on Friday, August 13, 2004 - 04:00 am:
Do both the formulae same or different.
I would like to get some comment on the correctness of the way I use for determination of noise for signal-to-noise ratio in an HPLC method. I work in the regulated environment and automized determination of noise is preferable and more convenient for QC labs. I´ve made a comparison-I´ve measured the peak height of noise:1) manually by ruler ("as in the old days")and 2)automatically by choosing the peak-to-peak noise parameter in the Millenium 32 software. I considered both values being comparable. My concern is: what is the correct way to calculate S/N? The peak-to-peak noise is then used in the formula according to Pharm Eur (EP) with some adjustment: S/N=2H/h, where h equals peak-to-peak noise of the blank during 1 min at the place where the component would be found and H is the component´s peak height. The other formula used to calculate S/N by some people is just S/N=H/h, where h is noise in the blank measured manually and H is the component´s height measured by Mil32. I guess there is a discrepancy between these two formulas (a factor of 2?). Could some experts in this field explain what is more correct to use?
Thanks a lot.
-------------------------------------------------------------------------------------------------------
By anila on Friday, July 30, 2004 - 08:53 pm:
Then what is the difference between 'Baseline noise' and 'peak to peak noise' fields in mil32.
For getting the 'p2p noise' , we need to select the 'detector noise and drift' tab, where as for base line noise, we need to select the "suitability" tab.
Which noise value has to be used in S/N ratio calculation.
can anybody please clarify me.
-------------------------------------------------------------------------------------------------------
By A on Saturday, July 31, 2004 - 06:51 am:
I use average peak to peak noise. I use this because if I zoom into the baseline and actually measure the noise (with a ruler), the values usually compare quite nicely. You get to define, in your SOP, which is the right one for your assay.
Peak-to-peak noise is defined as the sum of the maximum and minimum differences between each data point and the least-squares line.
Average peak to peak noise is the above averaged over the user defined time (often 30 seconds) during the define mesurement section (I like to use 2 minutes if I can).
Baseline noise is the amount of noise calculated for the region between the user-specified start and end times in the chromatogram
-------------------------------------------------------------------------------------------------------
By anila on Friday, August 13, 2004 - 04:00 am:
Do both the formulae same or different.
