What indicates the presence of lead when using AAS?

In the context of using Atomic Absorption Spectroscopy (AAS) for detecting lead, the correct indication of its presence is observed when the light is partially extinguished. AAS operates on the principle of measuring how much light is absorbed by a sample. When lead (or any element) is present in the sample, it absorbs specific wavelengths of light that correspond to its electronic transitions. This absorption leads to a reduction in the intensity of the light beam passing through the sample.

When light is partially extinguished, it signifies that lead is present in the sample as it has absorbed the light, which is a critical factor for accurate quantification of lead concentration. This phenomenon is key in distinguishing the elements present in a sample and determining their concentrations. Thus, the presence of lead is signified by a measurable decrease in light intensity in AAS, which directly reflects its concentration.