Hello,
We are developing DAD module on Clarity recently, but we don't know how to calculate the peak purity. After using the Agilent's control module--1200 Detectors in demo mode, we still have some questions.
In peak purity view, we can see two curves. One is the peak curve, the other is the peak purity curve. We can also see the average peak purity, but we don't know whether the peak is pure or not, .We can't see any other useful information about it.
In general, threshold is used to judge whether a peak is pure or not. Noise is used to calculate threshold. But we can't find anything about threshold and noise settings in Clarity.
Thanks for your answers.
How to determine the purity of a peak
Re: How to determine the purity of a peak
Peak Purity value is calculated as a match between the peak apex spectrum and all the spectra thorough the peak boundaries. Perfect match is represented by 1000. The values are plotted in the Peak profile window, the average is reported in the Result table. For pure peaks, the profile should be more or less rectangular and Peak Purity close to 1000.
In the PDA method, Peak Purity section, the Peak Purity Threshold (0-1000) and Absorbance Threshold (0-100%) are used to eliminate spectra not exceeding the set values, as they probably represent just noise and will affect the average value.
In the PDA method, Peak Purity section, the Peak Purity Threshold (0-1000) and Absorbance Threshold (0-100%) are used to eliminate spectra not exceeding the set values, as they probably represent just noise and will affect the average value.
Ivan Vinš
Re: How to determine the purity of a peak
Thanks for your reply, but we still have some questions.
1.Where is the "Peak profile window" ? I can't find it.
2.What does "Absorbance Threshold" use for?
3. Can Peak Purity Threshold be calculated automatically ? Is it only able to be set in the method ?
1.Where is the "Peak profile window" ? I can't find it.
2.What does "Absorbance Threshold" use for?
3. Can Peak Purity Threshold be calculated automatically ? Is it only able to be set in the method ?
Re: How to determine the purity of a peak
1) The peak purity profile for selected peak is displayed in the Peak Purity View pane of the PDA Chromatogram window.
2) Absorbance Threshold is used in the same way as Peak Purity Threshold to eliminate spectra with values below those limits (typically containing just noise) from the Peak Purity evaluation.
3) The calculated Peak Purity value is displayed in the Result table, there is no evaluation or calculation of the Peak Purity Threshold in Clarity. An User column could be defined to compare the calculated Peak Purity with some limit (using formula [Peak Purity]>=nnn), giving the 0 for fail and 1 for pass.
2) Absorbance Threshold is used in the same way as Peak Purity Threshold to eliminate spectra with values below those limits (typically containing just noise) from the Peak Purity evaluation.
3) The calculated Peak Purity value is displayed in the Result table, there is no evaluation or calculation of the Peak Purity Threshold in Clarity. An User column could be defined to compare the calculated Peak Purity with some limit (using formula [Peak Purity]>=nnn), giving the 0 for fail and 1 for pass.
Ivan Vinš
