A liquid analyzer for analyzing a liquid sample, comprising: a potentiostat in electrical communication with two or more electrodes (18, 20, 22) of an amperometric sensor, configured to measure signals generated by at least two of the two or more electrodes (18, 20, 22), and to control a voltage difference between at least two of the two or more electrodes (18, 20, 22); at least one calibration injection port adapted to receive a calibration reagent having a predetermined target analyte level of a target analyte; at least one automated valve communicating with the at least one calibration injection port and being openable and closable to pass one or more samples of the calibration reagent; and a control system having a processor executing processor executable code that when executed causes the processor to: - control the at least one automated valve to pass the calibration reagent through a liquid channel to the two or more electrodes (18, 20, 22); - control the 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 selected from a linear algorithm, a spline-based algorithm, an exponential algorithm, a least squares algorithm or a logarithmic algorithm; and - measure a target analyte concentration within the liquid sample using the calibration parameters. a potentiostat in electrical communication with two or more electrodes (18, 20, 22) of an amperometric sensor, configured to measure signals generated by at least two of the two or more electrodes (18, 20, 22), and to control a voltage difference between at least two of the two or more electrodes (18, 20, 22); at least one calibration injection port adapted to receive a calibration reagent having a predetermined target analyte level of a target analyte; at least one automated valve communicating with the at least one calibration injection port and being openable and closable to pass one or more samples of the calibration reagent; and a control system having a processor executing processor executable code that when executed causes the processor to: - control the at least one automated valve to pass the calibration reagent through a liquid channel to the two or more electrodes (18, 20, 22); - control the 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 selected from a linear algorithm, a spline-based algorithm, an exponential algorithm, a least squares algorithm or a logarithmic algorithm; and - measure a target analyte concentration within the liquid sample using the calibration parameters. - control the at least one automated valve to pass the calibration reagent through a liquid channel to the two or more electrodes (18, 20, 22); - control the 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 selected from a linear algorithm, a spline-based algorithm, an exponential algorithm, a least squares algorithm or a logarithmic algorithm; and - measure a target analyte concentration within the liquid sample using the calibration parameters.