SCX - strong cation exchanger. A typical strong cation exchange functional group would be a sulfonic acid.
selectivity - measures the difference of the retention of two particular components on a given column (adsorbent); the higher selectivity values the better the separation.
sensitivity - term which quantitatively describes the signal obtained per amount of sample introduced.
silanol - the Si-OH group found on the surface of silica gel. There are different strengths of silanols, depending on their location and relationship to each other. The strongest silanols are acidic and often lead to undesirable interactions with basic compounds during chromatography.
See surface chemistry.