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Peak Fraction Purity and Chromatographic Resolution: Gaussian Peaks Revisited



Andre Striegel, Deborah Striegel


For incompletely resolved peak pairs, the purity of the chromatographic or fractographic fractions is oftentimes underestimated by the common user. This results in wasted time and effort while trying to achieve higher resolution than needed for the intended use. While a choice regarding acceptable fraction purity is ultimately up to the user and will be dictated by the purpose for which the separation is being conducted, knowledge of fraction purity as a function of chromatographic resolution Rs can help make an informed decision in this regard. To this effect, we revisit here the relationship between peak fraction purity and Rs for pairs of Gaussian peaks, symmetric peaks ranging in Rs from 0.42 to 1.68 and asymmetric peaks of various analyte ratios and Rs values. Employing sophisticated yet highly accessible commercial software, we calculate, to a greater precision than previously reported, the purity resultant from midpoint or valley cuts of peak pairs, and also show the improvement gained from performing these cuts at either the maxima of the cumulative peak or at the locations in this peak corresponding to the centers of gravity of the individual component peaks. The methodology employed and equations given are applicable to Rs values other than those investigated here.


Chromatographic resolution, peak fraction purity, Gaussian peaks, computer simulations


Striegel, A. and Striegel, D. (2022), Peak Fraction Purity and Chromatographic Resolution: Gaussian Peaks Revisited, Chromatographia, [online],, (Accessed May 20, 2024)


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Created January 19, 2022, Updated November 29, 2022