Symmetrization of Peaks in Chiral Chromatography with an Area-Invariant Resolution Enhancement Method

Abstract

A majority of enantiomeric separations show some degree of peak asymmetry, which is detrimental to quantitative and semiquantitative chiral analysis. This paper presents a simple and rapid peak symmetrization algorithm for the correction or reduction of peak tailing or fronting in exponentially modified Gaussians. Raw chromatographic data can be symmetrized by adding a correct fraction of the first derivative to the chromatogram. The area remains invariant since the area under the first derivative is zero for a pure Gaussian and numerically close to zero for asymmetric peaks. A method of easily extracting the distortion parameter is provided, as well as insight into how pre-smoothing the data with the “perfect smoother” algorithm can suppress high frequencies effectively. The central difference method is also used to compute the first derivative, reducing root-mean-square noise by up to 28% compared to the standard forward difference method. A survey of 40 chiral separations is presented, demonstrating the range of asymmetry observed in chiral separations. Examples of symmetrization of the peaks from enantiomers in comparable and disproportionate concentrations are also provided. Artifacts of deconvolution are discussed, along with methods to mitigate such artifacts.

Automated Regularized Deconvolution for Eliminating Extra-Column Effects in Fast High-Efficiency Separations

“…Another point to note is that even after deconvolution, there is still a small amount of skew and excess kurtosis. This indicates that this chiral column is not an ideal Gaussian operator (under these conditions) and suffers from some of the characteristics of chiral chromatography that produce asymmetric peaks …”

“…This indicates that this chiral column is not an ideal Gaussian operator (under these conditions) and suffers from some of the characteristics of chiral chromatography that produce asymmetric peaks. 42 ■ CONCLUSIONS Liquid chromatography columns are now routinely manufactured that provide ultrahigh efficiencies, which are compromised by current instrumentation. Computational methods must be developed to remove these instrumental distortions.…”

Optimization of analytical method greenness scores: a case study of amino acid enantioseparations with carbonated aqueous systems

“…Note, in the case of enantioseparations that typically produce characteristic tailing and lower efficiency of the second enantiomer, higher resolution values are often needed (>2) to baseline resolve the enantiomers. 50 The first column of Fig. 4B contains the results of a pure carbonated water eluent, where 18 of the 38 compounds had a resolution >1.5.…”

Chiral Metal–Organic Framework Nanostructures for Chiral Channel-Dependent Enantioselective Sensing

“…Therefore, an efficient approach to chiral enantiomer recognition is crucial. Electrochemical assays have great application potential in chiral identification compared to traditional chiral identification methods (e.g., chromatography) − due to their advantages of ease of operation, high sensitivity, real-time detection, and absence of background interferences . However, the development of electrochemical chiral sensors remains a major challenge due to the lack of effective chiral selectors, , particularly the construction of chiral interfaces …”