Abstract: An apparatus is disclosed for use in a charged particle instrument which defines an inner volume therein. The apparatus comprises an adaptor (22) having a first portion adapted for attachment to a part (20) of a gas injection system (18) of a charged particle instrument which is located within an inner volume of such an instrument; and a second portion arranged to receive a tool (24) adapted for interaction with a sample (14) located in the inner volume of such an instrument.