The system can also be used to measure glucose in other fluids, such as cell culture medium. Use of enzymes other than glucose oxidase (e.g., cholesterol oxidase, lactate oxidase, or D- 3-hydroxybutyrate dehydrogenase15) will enable the measure- ment of other metabolites, (e.g., cholesterol, lactate, or D-3- hydroxybutyrate, respectively), making this system versatile for general clinical applications. It also has the potential for multiplexed analyses. The analytical platform can be adapted for checking water quality using anodic stripping voltammetry, as well