To determine the concentration of lead in a sample of water using atomic absorption spectroscopy AAS , follow these steps:1. Sample collection and preparation: Collect a representative water sample and filter it through a 0.45 m filter to remove any suspended particles. This step is crucial to avoid clogging the nebulizer and to minimize interferences during the analysis.2. Acid digestion: To ensure that all lead is in a soluble form, perform an acid digestion of the sample. Add concentrated nitric acid HNO3 to the filtered sample and heat it gently to break down any insoluble lead compounds. After cooling, dilute the sample to a known volume with deionized water.3. Calibration: Prepare a series of lead standard solutions with known concentrations by diluting a certified lead standard with deionized water and acid matrix. These solutions will be used to create a calibration curve.4. Instrument setup: Set up the atomic absorption spectrometer with a lead Pb hollow cathode lamp as the light source. Choose the appropriate wavelength for lead detection usually around 217 nm and set the slit width according to the manufacturer's recommendations.5. Sample analysis: Aspirate the lead standard solutions and the digested water sample into the nebulizer of the AAS. The nebulizer will create a fine aerosol that is carried into the flame, where the lead atoms will be atomized and absorb the light from the hollow cathode lamp. The absorbance of the light is proportional to the concentration of lead in the sample.6. Data analysis: Plot the absorbance values of the lead standard solutions against their concentrations to create a calibration curve. Use this curve to determine the concentration of lead in the water sample by interpolating the absorbance value of the sample.Factors to consider when preparing the sample and running the analysis:1. Matrix interferences: The presence of other elements or compounds in the sample may interfere with the absorption signal of lead. To minimize matrix interferences, use a method of background correction, such as deuterium background correction or Zeeman background correction.2. Chemical interferences: Some chemical species may cause a decrease or increase in the absorption signal. To minimize chemical interferences, use a releasing agent or a protective agent during the analysis.3. Instrumental parameters: Optimize the instrumental parameters, such as the fuel-to-oxidant ratio, the burner height, and the lamp current, to achieve the best sensitivity and precision.The limit of detection LOD for lead using AAS is typically around 1-5 g/L, depending on the instrument and method used. This LOD is generally lower than other methods, such as colorimetric or titrimetric methods, making AAS a more sensitive technique for detecting lead in water samples. However, other techniques like inductively coupled plasma mass spectrometry ICP-MS can achieve even lower LODs sub-g/L levels and can simultaneously analyze multiple elements, making it a more powerful technique for detecting heavy metals in water samples.