Answer please!

[DR]

It depends.

There are numerous chromatography overviews and resources linked up in the sticky section of these forums. Do your homework there. The link Tom previously provided should cover this as well.

[tom jupille]

The slightly longer answer is that it depends on what type of chromatography you are talking about.

As a *very* broad generalization:

In "reversed-phase" (ironically, the most popular type) increasing the polarity of the mobile phase increases retention.

In "normal-phase", increasing the polarity of the mobile phase decreases retention.

We can explain much of what goes on at the "boy scout merit-badge" level by the old saying "Like dissolves like and like sticks to like."