X-ray apparatus 10 includes an X-ray source (22), an X-ray detector (28) facing the X-ray source. Inlet (6) accepts a stream of particles and a guide system (18) guides the stream of particles (16) in free space between the X-ray source (22) and detector (28) so that X-ray analysis can be carried out on the particles in the stream (16) in a sample region (21) between the source (22) and the detector (28).