System maps for the Kinetex Phenyl-Hexyl column and correlation diagrams for columns of similar selectivity (Kinetex C8 and Phenyl-Hexyl) and dissimilar selectivity (Kinetex EVO C18 and Biphenyl) is used to illustrate the general approach to selectivity evaluation. Once again, this highlights the benefits of the shorter diffusion path associated with Kinetex core-shell technology, which results in a significant improvement in column efficiency, peak shape and overall analysis time. Compatible with All Analytical HPLC/UHPLC Systems. This versatile column can easily upgrade existing fully porous 5 m and 3 m methods to shorten run time, increase sensitivity, and even provide greater resolution with much higher efciency levels. System constants determined at 10 % (v/v) increments of organic solvent were utilized for the construction of system maps and correlation diagrams on Kinetex columns with octadecylsiloxane-bonded (C18 and EVO C18), diisobutyloctadecylsiloxane-bonded (XB-C18) octylsiloxane-bonded (C8), biphenylsiloxane-bonded (Biphenyl), phenylhexylsiloxane-bonded (Phenyl-Hexyl) and pentafluorophenylpropylsiloxane-bonded (F5) silica stationary phases for 20-70 % (v/v) methanol- and acetonitrile-water mobile phases. Because the Kinetex 2.6 m core-shell (superficially porous) particle morphology provides ultra-high column efficiency on any HPLC or UHPLC system, the investigation also included a comparison to a conventual fully porous 1.9 m UHPLC column. The Kinetex C8 is a core-shell based particle with a bonded silica phase ideal for analysis of very hydrophobic compounds. For all columns and mobile phase compositions the calibration models with n = 35 had a range for the coefficient of determination from 0.999 to 0.970 with < 5 % smaller than 0.99 (84 models) and a standard error of the estimate from 0.011 to 0.057 with 75 % < 0.030. The predictive capability of the calibration models was evaluated for an external test set for 50 % (v/v) methanol-water for the same columns with a typical root mean square error of prediction (log k) of 0.028 for the thirty-five calibration compounds ( n = 35) models. The number and identity of the calibration compounds was optimized by considering the statistical quality of the calibration models, the absolute value for the standard deviation of the individual system constants, and the closeness of the estimated system constants for the calibration models to the values for the full data set on seven core-shell columns with different morphology for mobile phases containing 50 % (v/v) methanol- or acetonitrile-water. This versatile column can easily upgrade existing fully porous 5 m and 3 m methods to shorten run time, increase sensitivity, and even provide greater resolution with much higher efficiency levels. The Kennard-Stone uniform mapping algorithm was employed to select the calibration compounds from a larger database of compounds with known retention properties used previously for column selectivity evaluation. The Kinetex 2.6 m Polar C18 is a core-shell based particle with a polar modified surface and a C18 alkyl phase. For the selectivity evaluation of core-shell silica, siloxane-bonded reversed-phase columns by the solvation parameter model a minimal set of thirty-five calibration compounds were identified for applications with mobile phases containing from 20-70 % (v/v) methanol- or acetonitrile-water.
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