Atomic absorption spectroscopy AAS is a widely used technique for determining the concentration of specific elements, such as lead, in a given sample. To quantify the concentration of lead in a water sample using AAS, follow these steps:1. Sample preparation: Collect a representative water sample and filter it to remove any suspended particles or debris. This can be done using a syringe filter or a filtration apparatus. It is important to use acid-washed glassware and plasticware to avoid contamination.2. Acid digestion: To ensure that all lead in the sample is in a soluble form, perform an acid digestion. Add a small volume of concentrated nitric acid HNO3 to the water sample and heat it gently on a hot plate until the sample volume is reduced by half. This step converts any insoluble lead compounds into soluble lead nitrate. Allow the sample to cool and then dilute it to a known volume with deionized water.3. Calibration curve: Prepare a series of lead standard solutions with known concentrations by diluting a certified lead standard with deionized water. These solutions will be used to create a calibration curve, which will help determine the concentration of lead in the water sample. Make sure to include a blank solution deionized water as a reference.4. Instrument setup: Set up the atomic absorption spectrometer according to the manufacturer's instructions. Choose the appropriate lamp a lead hollow cathode lamp and set the wavelength to 283.3 nm, which is the optimal wavelength for lead detection. Adjust the slit width, lamp current, and other parameters as needed.5. Calibration: Measure the absorbance of each lead standard solution using the AAS instrument. Plot the absorbance values against the known lead concentrations to create a calibration curve. Make sure to measure the blank solution as well and subtract its absorbance from the absorbance of the other solutions to account for any background signal.6. Sample analysis: Measure the absorbance of the acid-digested water sample using the AAS instrument. Subtract the blank absorbance value to obtain the corrected absorbance of the sample.7. Quantification: Use the calibration curve to determine the concentration of lead in the water sample. Locate the corrected absorbance value of the sample on the y-axis of the calibration curve and find the corresponding lead concentration on the x-axis. This value represents the concentration of lead in the acid-digested sample. To obtain the concentration of lead in the original water sample, multiply this value by the dilution factor used during the acid digestion step.8. Report the results: Report the concentration of lead in the water sample, along with any relevant information about the sample collection, sample preparation, and instrument parameters. Make sure to include the units of concentration e.g., g/L or ppb and any uncertainties associated with the measurement.