Approaches to estimate the time and height at the peak maximum in liquid chromatography based on a modified Gaussian model

The time and height at the peak maximum are key parameters to describe a chromatographic peak with prediction or optimization purposes, or in the qualitative/quantitative analysis of samples. Three different approaches to estimate these parameters, using the experimental points in the peak maximum region, are here described and compared. The approaches are based on the reliable description of the peak profile using a modified Gaussian model with a parabolic variance (PVMG). In the first approach, non-linear fitting of the chromatographic data to the PVMG model is carried out to obtain the time and height at the peak maximum (Approach I). In the other two approaches, the PVMG model is linearized to carry out a linear fitting. In each case, the optimal number of processed points was assessed. The three approaches yielded highly satisfactory results, being Approach I the best in terms of accuracy and robustness. The assessment of the accuracy in the estimations was carried out using simulated peaks. These peaks were built with the parameters obtained from real peaks for several probe compounds eluted under reversed-phase liquid chromatographic (RPLC) conditions, to which noise was added.