We will explore the hydrophobic-subtraction model and how the model relates to retention mechanisms in HILIC, mixed-mode and reversed phase techniques. Particular attention will be paid to the solutes they are most frequently used for. By utilizing the model, we will explore and expand upon the individual terms in order to understand the effects of each term in HILIC and mixed-mode retention. Examples from the model, as well as applicated examples, will be used to demonstrate the mechanism for each term.

The selectivity and retention will be demonstrated on selected phases that were designed to accentuate selected terms. These fundamental interactions are the drivers in every liquid separation we perform, regardless of whether they are marketed as HILIC, mixed-mode, or reversed phase. Understanding, and in some cases accentuating, these interactions can lead to simpler method development which yield much more consistent methods and results.