A model for the description, simulation, and deconvolution of skewed chromatographic peaks

A family of models is proposed for the description of skewed chromatographic peaks, based on the modification of the standard deviation of a pure Gaussian peak, by the use of a polynomial function, h(t) = He-(1/2([t-tR]/[s0+s1(t-tR)+s2(t-t)2+...])2), H and t(R) are the height and time at the peak maximum, respectively. The model has demonstrated a high flexibility with peaks of a wide range of asymmetry and can be used to accurately predict the profile of asymmetrical peaks, using the values of efficiency and asymmetry factor measured on experimental chromatograms. This possibility permits the simulation of chromatograms and the optimization of the separation of mixtures of compounds producing skewed peaks, where both the position and peak shape are considered. A first-degree polynomial was adequate for peaks of moderate asymmetry, but higher degree polynomials were preferable for peaks showing a high asymmetry, including those with negative skewness. The proposed models can be employed in the resolution of overlapped peaks in binary and ternary mixtures of compounds, or to improve the accuracy in the evaluation of peak shape parameters. The results obtained with the proposed models were comparable or even superior to those achieved with the exponentially modified Gaussian model.