chain length - the length of carbon chain in the hydrocarbon portion of a reversed-phase packing. It is expressed as the number of carbon atoms (e.g. C8, C18).
channeling - occurs when voids created in the packing material of a column may cause mobile phase and accompanying solutes to move more rapidly that the average flow velocity, resulting in band broadening. The voids are created by poor packing or by erosion of the packed bed.
check valve - stopper valve in reciprocating piston pump which allows solvent to flow in only one direction. Usually consists of the sapphire ball and ring (sedle).
chemisorption - sorption caused by a chemical reaction with the adsorbent surface. Most such interactions are irreversible; usually occur on packings with reactive functional groups such as silanol or bonded amino phases.