Atomic absorption spectroscopy AAS is a widely used analytical technique for determining the concentration of various elements, including lead, in water samples. To quantify the concentration of lead in a water sample using AAS, follow these steps:1. Sample collection and preparation: Collect a representative water sample from the source. The sample should be stored in a clean, acid-washed container to avoid contamination. If the sample cannot be analyzed immediately, it should be preserved by adding a few drops of concentrated nitric acid HNO3 to lower the pH below 2, which helps to prevent precipitation and adsorption of lead onto the container walls.2. Digestion if necessary : If the sample contains particulate matter or complex organic compounds, a digestion step may be necessary to break down these compounds and release the lead into a more easily measurable form. This can be done using a mixture of concentrated nitric acid HNO3 and hydrogen peroxide H2O2 or other suitable digestion methods. After digestion, the sample should be filtered and diluted to a known volume.3. Calibration: Prepare a series of lead standard solutions with known concentrations, covering the expected concentration range of the sample. These standards will be used to create a calibration curve, which will be used to determine the concentration of lead in the water sample. Analyze each standard using the AAS instrument and record the absorbance values.4. Sample analysis: Analyze the water sample using the same AAS instrument settings as for the calibration standards. Record the absorbance value of the sample.5. Calibration curve and concentration determination: Plot the absorbance values of the calibration standards against their respective lead concentrations to create a calibration curve. Using the absorbance value of the water sample, interpolate or extrapolate the lead concentration from the calibration curve.6. Quality control: To ensure the accuracy and reliability of the results, it is essential to include quality control measures, such as analyzing a blank deionized water , a spiked sample sample with a known amount of lead added , and a certified reference material if available . These quality control samples should be analyzed alongside the water sample and calibration standards.7. Report the results: Report the concentration of lead in the water sample, along with any relevant information about the sample collection, preparation, and analysis, as well as the quality control results.By following these steps, you can accurately quantify the concentration of lead in a water sample using atomic absorption spectroscopy.