The continuous emission of agricultural sewage and domestic wastewater causes the increase of nutrient content in the offshore environment, which seriously harms the coastal ecosystem. Thus, it is necessary to realize in-field rapid detection of nutrient content in complex water. The electrochemical sensors loaded with nanomaterials provide a low-cost and convenient solution with great sensitivity for in-field pollutants detection. Nonetheless, the accuracy of nanomaterials-based electrochemical detection was usually degraded in complex offshore waterbodies by cross-sensitivity from salinity status, co-pollutants, environmental conditions variation such as temperature and pH value, as well as the relatively low reproducibility and stability of nanomaterials. To address the accuracy issues in complex water, a simultaneous calibration and detection (SCD) strategy is proposed. The SCD strategy consists of a linear regression algorithm and a sensor composed of a series of identical discrete electrochemical sensing units. By detecting a series of samples, including actual water sample, diluted or concentrated actual water samples, the concentration of the analyte can be directly derived by obtaining the electrochemical response current of these samples and the concentration of the added concentrated analyte. Furthermore, A compact device was implemented capable of in-field sampling and electrochemical sensing automatically with the SCD strategy. Applied in the in-field nitrite detection in natural waterbodies, the SCD strategy and the automatic detection device have exhibited a higher accuracy than the standard electrochemical calibration method, good stability and consistency between different batches of sensors.

in-field, electrochemical detection, offshore nutrition detection, simultaneous calibration and detection