A fluid tester includes an inlet for a fluid path, an ionization chamber defining at least part of the fluid path located downstream from the inlet, a charge chamber configured to subject a fluid to an electric field defining at least part of the fluid path located downstream of the ionization chamber, a patch holder configured to hold a patch into the fluid path downstream of the electric chamber and an outlet for the fluid path. A method of testing a fluid includes ionizing a fluid, moving particles suspended in the fluid by passing the fluid through an electric field, passing the fluid through a patch and analyzing a patch.