To determine the concentration of copper in a given sample of water using spectrophotometry, follow these steps:1. Preparation of reagents and standards: a. Prepare a copper standard solution by dissolving an appropriate amount of copper sulfate CuSO45H2O in distilled water to make a 1000 ppm mg/L stock solution. b. Dilute the stock solution to prepare a series of standard solutions with known concentrations e.g., 0.5, 1, 2, 4, 6, 8, and 10 ppm using distilled water. c. Prepare a reagent blank by mixing distilled water with the color-developing reagent e.g., neocuproine or bathocuproine that will react with copper ions to form a colored complex.2. Sample preparation: a. Collect the water sample and filter it through a 0.45 m filter to remove any suspended particles. b. Acidify the sample with a few drops of concentrated nitric acid HNO3 to prevent precipitation of copper salts. c. If necessary, pre-concentrate the sample using a suitable method, such as evaporation or solid-phase extraction, to increase the copper concentration to a detectable level.3. Color development: a. Pipette a known volume e.g., 10 mL of each standard solution, the reagent blank, and the water sample into separate test tubes or cuvettes. b. Add a known volume e.g., 1 mL of the color-developing reagent to each test tube or cuvette. c. Mix the contents of each test tube or cuvette thoroughly and let them stand for a specified time e.g., 10-15 minutes to allow the colored complex to form.4. Spectrophotometric analysis: a. Set the spectrophotometer to the appropriate wavelength for the copper complex e.g., 450 nm for the neocuproine-copper complex or 480 nm for the bathocuproine-copper complex . b. Zero the spectrophotometer using the reagent blank. c. Measure the absorbance of each standard solution and the water sample. d. Plot a calibration curve by plotting the absorbance values of the standard solutions against their corresponding copper concentrations.5. Data analysis: a. Determine the concentration of copper in the water sample by comparing its absorbance value to the calibration curve. b. If the sample was pre-concentrated, adjust the calculated concentration by taking into account the pre-concentration factor. c. Report the concentration of copper in the water sample in the appropriate units e.g., ppm or g/L .By following these steps, you can accurately determine the concentration of copper in a given sample of water using spectrophotometry.