Purity threshould & Purity angle

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Santosh@India
Santosh@India's picture
Purity threshould & Purity angle

Does any one explains me the meaning and significance of term " Purity Threshould " and " Purity angle" , How it can be determined, I am using PDA detector to my HPLC system.
 

Dr. Analytical
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The meaning would probably

The meaning would probably depend on the context.  Please give us more information.  I am not familiar with "purity angle."  The Threshold could refer to the minimum purity of a reference standard, or the minimum quantity of active ingredient in a formulation, or many other things.

Santosh@India
Santosh@India's picture
Dr.Analytical , Thanks for

Dr.Analytical , Thanks for the replay.
The term " Purity Angle" and "Purity Threshould" is used for identifying any the co-elution of any other impurity with the analyte. These terms are instrumental parameters,  want to know how the instrument will calculate them and what is there meaning.These are only associated with PDA detector.

Dr. Analytical
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Calculations of "Peak Purity"

Calculations of "Peak Purity" are different for each software program.  Which program are you using?

I am familiar with the Agilent ChemStation program.  The "threshold" means the minimum purity value that means the peak is pure.  This value is usually based on a statistical analysis of the noise in the spectra.  If the measured value is larger than the threshold, then the peak is considered pure.  Otherwise, the peak is considered impure.

Peak Purity is not 100% accurate, so you must use the results with caution.

SIVAGANESH86
SIVAGANESH86's picture
The spectral contrast angle
  • The spectral contrast angle measures the shape difference between two spectra.

The Purity angle is a measure of the spectral heterogeniety of a peak based on the comparison of spectra over all the peak, using the spectral contrast angle

  • The non-ideal effects are quantified and provided as a value of the Threshold angle.
  • When the peak is pure, the Purity angle is lower than the Threshold angle