Prediction of retention times and peak shape parameters of unknown compounds in traditional Chinese medicine under gradient conditions by ultra performance liquid chromatography

A method for the prediction of retention times and peak shape parameters of compounds of unknown structures in complex sample under linear gradient mobile phase conditions was established. Taking traditional Chinese medicine (TCM)—Rhizoma Corydalis as an example, the chromatographic retention parameters and peak shape parameters of 24 compounds were studied. After recognition of each peak under five different linear gradient conditions, the binary parameters equation was established to calculate the retention parameters on ultra performance liquid chromatography (UPLC) with 2.1 mm i.d. column packed with 1.7 μm particles. And further retention times under other binary gradient conditions were predicted. The largest relative error of predicted retention time for each compound in R. Corydalis was 0.75%. The exponentially modified Gaussian (EMG) model and automatic peak curve-fitting method were used to resolve the overlapping peaks, to calculate the peak shape parameters and to obtain the peak shape rules. The peak shape parameters σ, τ and Wh/2 possessed the linear relationship with the equivalent retention time tR*. Based on peak shape rules, peak shape parameters under other mobile phase conditions were predicted. The predicted peak shape parameters were coincident with the experimental results.