Method and apparatus

Abstract

An aspect of the disclosure provides a sieve pack for an ion mobility spectrometer, the sieve pack comprising: an inlet, for connection to a pneumatic system of the ion mobility spectrometer to receive a flow of gas from said pneumatic system; a first outlet, for connection to said pneumatic system for providing a cleaned dried flow of gas to said pneumatic system; a first direction changing conduit extending between a first end of the sieve pack and a second end of the sieve pack, wherein the second end is spaced in an axial direction from the first end, wherein: the first direction changing conduit is configured to hold a sieve material for cleaning and drying air; the first direction changing conduit comprises at least one turn around the axial direction; and, the first direction changing conduit is connected to the inlet and the first outlet and configured to carry the flow of gas from the inlet through the sieve material to the first outlet. [Figure. 1]