Chemometric methods to classify stationary phases for achiral packed column supercritical fluid chromatography

Abstract

This paper investigates classification models for packed columns used in supercritical fluid chromatography (SFC). Forty-eight columns of varied stationary phase chemistries available on the market are evaluated. The retention factors of 134 selected test compounds are used to compute hierarchical cluster analysis (HCA), principal component analysis (PCA), and quantitative structure-retention relationships (QSRRs). The use of HCA in conjunction with either PCA of QSRRs provides a classification of columns that is consistent with the experience of the SFC chromatographer. Besides, different coefficients, namely, Pearson correlation coefficient (r), selectivity difference (s 2 ), distance (L), and angle (θ), were calculated between all couples of columns to identify a ranking index, which would provide meaningful information whenever two columns need to be compared on an objective basis. This can be the case either when an equivalent is sought for replacement of a reference column or when an orthogonal column is desired to achieve complementary selectivity. It is concluded that the θ angle and the normalized distance L /u are the best coefficients, allowing for a meaningful comparison between two columns.

Use and practice of achiral and chiral supercritical fluid chromatography in pharmaceutical analysis and purification

“…It was shown several times that the selectivity of a given column employed in HPLC or in SFC may be very different . To assist the users of achiral SFC in the selection of orthogonal columns, the classification of columns dedicated to SFC, developed by West and Lesellier , can be helpful. The physicochemical characteristics of stationary phases were studied with quantitative structure‐retention relationships, to characterize more than 80 stationary phases .…”

Evolution and Current Trends in Liquid and Supercritical Fluid Chromatography

“…Systematic classification of stationary phases was proposed by Lesellier and West who developed a tool based on solvatochromic model that groups the retention properties of a wide range of polar and non-polar phases. This tool is very useful for the column screening process, it allows the selection of sets of columns which exhibit the most orthogonal selectivities [283][284][285]. A derived approach was besides successfully implemented in the pharmaceutical industry [286].…”

Assessment of column selection systems using Partial Least Squares

“…Availability of more than 1000 commercial stationary phases [2,3], makes column selection a crucial process. Therefore, it is not surprising that numerous papers [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] describing various attempts to achieve this are being continuously published.…”