To efficiently and accurately quantify the levels of heavy metals, such as lead and mercury, in a given water sample using atomic absorption spectroscopy AAS method, follow these steps:1. Sample collection and preparation: Collect a representative water sample from the source, ensuring that it is free from contamination. Filter the sample to remove any suspended particles and store it in a clean, acid-washed container. Acidify the sample with a small amount of concentrated nitric acid to preserve the heavy metals and prevent adsorption onto the container walls.2. Calibration: Prepare a series of calibration standards containing known concentrations of lead and mercury by diluting stock solutions with deionized water. Acidify these standards with nitric acid to match the sample matrix. Measure the absorbance of each standard using the AAS instrument and plot a calibration curve of absorbance versus concentration for both lead and mercury.3. Sample analysis: Dilute the water sample, if necessary, to bring the heavy metal concentrations within the range of the calibration curve. Measure the absorbance of the diluted sample using the AAS instrument. Ensure that the instrument settings, such as wavelength, slit width, and lamp current, are optimized for the analysis of lead and mercury.4. Quantification: Use the calibration curves to determine the concentrations of lead and mercury in the sample. Multiply the concentrations by the dilution factor, if applicable, to obtain the original concentrations in the water sample.5. Quality control: Analyze a blank deionized water and a spiked sample known concentration of heavy metals added to the water sample alongside the water sample to ensure the accuracy and precision of the method. Calculate the recovery of the spiked sample to assess the method's performance.6. Data interpretation: Compare the measured concentrations of lead and mercury in the water sample with regulatory limits or guidelines to determine if the levels are within acceptable ranges.By following these steps, you can efficiently and accurately quantify the levels of heavy metals, such as lead and mercury, in a given water sample using the atomic absorption spectroscopy method.