To determine the concentration of iron in a given sample using spectrophotometry, you can follow these steps:1. Prepare the sample: If the sample is solid, dissolve it in a suitable solvent, usually a diluted acid like hydrochloric acid HCl or nitric acid HNO3 , to extract the iron ions. If the sample is already in a liquid form, you may need to filter or centrifuge it to remove any suspended particles.2. Select a suitable complexing agent: To measure the concentration of iron using spectrophotometry, you need to form a colored complex with iron ions. A common complexing agent for iron is 1,10-phenanthroline, which forms a red-orange complex with Fe II ions.3. Convert Fe III to Fe II : If the sample contains Fe III ions, you need to reduce them to Fe II ions before forming the complex. This can be done by adding a reducing agent like hydroxylamine hydrochloride NH2OHHCl to the sample.4. Formation of the colored complex: Add an excess of the complexing agent 1,10-phenanthroline to the sample containing Fe II ions. The Fe II -phenanthroline complex will form, which has a characteristic red-orange color.5. Calibration curve: Prepare a series of standard solutions with known concentrations of iron, and treat them with the same complexing agent and reducing agent as the sample. Measure the absorbance of each standard solution at the wavelength of maximum absorbance usually around 510 nm using a spectrophotometer. Plot the absorbance values against the iron concentrations to create a calibration curve.6. Measure the sample absorbance: Measure the absorbance of the colored complex in the sample at the same wavelength used for the calibration curve.7. Determine the concentration: Use the sample's absorbance value and the calibration curve to determine the concentration of iron in the sample.8. Calculate the concentration in the original sample: If you diluted the sample during the preparation step, you need to multiply the determined concentration by the dilution factor to obtain the concentration of iron in the original sample.By following these steps, you can accurately determine the concentration of iron in a given sample using spectrophotometry.