Abstract: The invention relates to a cartridge (1) for a magnetic flow cytometer, mainly extending in a x-y-plane, with an inlet (2) for injecting a sample (15) into the cartridge (1), a blister (3) for a buffer solution (21) with magnetic markers to mark pregiven particles (16, 16?) of the sample (15), an outlet, and a fluid channel (9), the fluid channel (9) comprising a first part that connects the inlet (2) with the blister (3) and a second part that connects the first part with the outlet, wherein the second part of the fluid channel (9) comprises an enrichment zone (5) with mechanical guiding structures to focus marked particles (16, 16?) of the sample (15) in a predetermined subsection of the fluid channel (9) and a measuring zone (6) between the enrichment zone (5) and the outlet, the measuring zone (6) comprising a magnetic field sensor (14) in the predetermined subsection of the fluid channel (9) in order to provide simplified and accelerated means for measuring particles, in particular concentrations of part