Methods and systems for measuring the oxidation-reduction potential of a fluid sample are provided. The system includes a test strip with a sample chamber adapted to receive a fluid sample. The sample chamber can be associated with a filter membrane. The test strip also includes a reference cell. The oxidation-reduction potential of a fluid sample placed in the sample chamber can be read by a readout device interconnected to a test lead that is in electrical contact with the sample chamber, and a reference lead that is in electrical contact with the reference cell. Electrical contact between a fluid sample placed in the sample chamber and the reference cell can be established by a bridge. The oxidation-reduction potential may be read as an electrical potential between the test lead and the reference lead of the test strip.