A column 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.Endfitting The fining 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.