Abstract: | Abstract A new method has been developed for field screening of copper (II) in water samples, which is based on an enzyme inhibition reaction between copper (II) and nitrate reductase. The concentration of copper (II) was acquired by indirect determination the reaction product (nitrite) with a mini optical reflection sensor. Under the optimum conditions, the calibration graph was linear in the range of 5.0–50 ng mL?1. The limit of detection was 0.5 ng mL?1. This method has been used for the field screening of copper (II) with satisfactory results. |