A device for analyzing simultaneously multiple analytes in a fluid of unknown composition. The device includes a plurality of sensors, a light source for providing light to shine on the sensors, light detectors, and a processor. The sensors are exposed to a sample of the fluid of unknown composition. The plurality of sensors includes groups of sensors, each group targeting a specific analyte and including one or more sensors that contain an analyte-specific chemical that interacts more specifically with one analyte than with some other analytes to be analyzed. Each sensor in each group has a different chemical interacting with the analyte to target it. The light source shines light on the sensors of the plurality of sensors to cause light interaction with the sensors. The differences in the sensors lead to differences in the light interaction. The light detectors detects the light interaction by the sensors. The processor analyzes the light interaction by the sensors to take into account interference in light interaction among the analytes, thereby determining the concentration of each of the analytes in the fluid.