A control system for a fluid analyzer is described. The control system has a processor executing processor executable code to: control a potentiostat to apply a first voltage potential sufficient to induce a first electrochemical reaction of a target analyte or a reaction byproduct of the target analyte in a sample of the calibration reagent and receive a first reading from the potentiostat; control the potentiostat to apply a second voltage potential insufficient to induce a second electrochemical reaction of the target analyte or a reaction byproduct of the target analyte in the sample of the calibration reagent and receive a second reading from the potentiostat; calculate calibration parameters using the first reading, the second reading and a multi-point calibration algorithm; and measure a target analyte concentration within the fluid sample using the calibration parameters.