Experimental design and re-parameterization of the Neue-Kuss model for accurate and precise prediction of isocratic retention factors from gradient measurements in reversed phase liquid chromatography

Improved hydrophobic subtraction model of reversed-phase liquid chromatography selectivity based on a large dataset with a focus on isomer selectivity

“…where kw, S1 and S2 are solute/condition-specific model parameters. The fitting was carried out using a re-parameterization of the NK model where the model parameters were calculated based on the retention factor at  = 0.30 as a reference point (kref) instead of the more conventional kw, as described in a recent publication [31]. The model is then given in revised form as…”

“…However, in 72 of the 1157 cases, the retention factor at 40% ACN was not measured experimentally, in most cases because the retention factor was too large to be practically determined at this mobile phase composition. Therefore, these missing values were estimated by fitting the available data for those column/solute combinations to the NK model as described above [31]. This methodology allowed for the rejection of outliers [31], and provided stable estimates for the NK parameters.…”

“…Therefore, these missing values were estimated by fitting the available data for those column/solute combinations to the NK model as described above [31]. This methodology allowed for the rejection of outliers [31], and provided stable estimates for the NK parameters. For three solutes -2,2'-dinaphthyl ether, glecaprevir and o-terphenylmore than 50% of the retention factors on the 13 columns were missing, because of very high retention, and these solutes were eliminated from further analysis.…”