elutropic series - a relative ranking of HPLC solvents ranging from non-polar to very polar properties. Polarity effects are due, in part, to dielectric constant, dipole moment and hydrophobic-hydrophillic properties.
endcapping - an adsorbent is said to be endcapped when a small silylating agent (e.g. trimethylchlorosilane) is used to bond residual silanol groups on a packing surface. Most often used with reversed-phase packings. May cut down on undesirable adsorption of basic or ionic compounds.
See also endcapping.
endfitting - the fitting at the end of the column that connects it to the injector or detector. Most HPLC endfittings contain a frit to hold the packing and have a low dead volume for minimum band spreading. Usually made of stainless steel.
See column hardware.
excess adsorption - the amount of analyte concentrated on the surface expressed as the surface excess over the amount which would be on the surface in the absence of adsorption forces.
See adsorption from solutions.