Systems, devices, and methods for point-of-use testing for fluid contamination

A system for sampling fluid, comprising:

• a filter housing having an inlet and an outlet;
• at least one filter disposed in the filter housing;
• a fluid storage chamber in fluid communication with the at least one filter;
• at least one electrode in fluid communication with the at least one filter;
• and
• one or more reagents located in at least one of the filter housing, the at least one filter, and one or more electrodes of the at least one electrode,
• wherein the filter housing and the at least one filter are configured such that one or more cells contained within a fluid sample that is passed into the filter housing via the inlet becomes located in at least one concentration region disposed in the filter housing and reacts with the one or more reagents to produce one or more redox species, the one or more redox species being part of fluid from the fluid sample and other material that passes out of the filter housing via the outlet, and
• wherein the one or more electrodes of the at least one electrode is configured to measure one or more electrochemical properties of the produced one or more redox species.