Abstract: Selective regions of the overlapping hyphenated chromatographic data are crucial for the resolution via chemometric methods. The latent projective graph(LPG) is the common technique for identifying the selective regions, in which the selective regions are revealed by the appearance of sequences of consecutive points mapping as segments of straight lines. However, according to our results, the straight lines in the LPG of the system comprising some closely eluting components with fairly similar spectra may not always necessarily correspond to the real selective regions. In this work, three-dimensional LPG(3D-LPG) was developed, and a new chemometric technique T-plot was proposed to identify the linear segments of 3D-LPG corresponding to the selective regions. The performance and efficiency of the proposed methods were illustrated on both the simulated and experimental data, and the results show that the 3D-LPG can provide much more information and deeper insights into the structure of the data, outperforming the present 2D version in revealing the selective regions when the spectra of some coeluting components are quite similar. Moreover, T-plot is proved to be effective in identifying the linear segments in 3D-LPG.

Key words: Hyphenated chromatography, Selective region, Three-dimension, Latent projective graph, HELP