Described herein are various embodiments of a test strip, which may be capable of measuring an analyte. The test strip may include a working electrode and a reference electrode where the reagent formulation is disposed on the working electrode. The reagent formulation may be coated onto the test strip. The reagent formulation includes an enzyme, a ruthenium hexamine mediator, and a solution for dissolving the enzyme and the ruthenium hexamine mediator. The reagent formulation may be coated onto the test strip. The reagent formulation includes an enzyme, a ruthenium hexamine mediator, and a solution for dissolving the enzyme and the ruthenium hexamine mediator. The ruthenium hexamine has a concentration range from about 15% to about 20% (weight of mediator/volume) of solution. The enzyme may be either glucose oxidase and glucose dehydrogenase.