distribution coeffcient (K) - syn. partition coefficient; ratio of the concentration of solute or sample in the stationary phase (liquid) to the concentration of the same in the gas phase. Appropriate to Gas-liquid chromatography where well defined phases are used. Historically was transferred to HPLC where it used as a synonym of the adsorption coefficient, or Henry constant.

dual piston pump - see "reciprocating piston pump".

eddy diffusion - phenomena occurring in packed columns due to lack of homogeneity of packing; expressed quantitatively by the first term of the van Deemter equation; produces peak broadening.

See band broadening theory.

efficiency - column characteristic expressed quantitatively by the number of theoretical plates; efficient columns have many theoretical plates and show only limited band broadening.

See column efficiency.