What analytical methodologies are capable of identifying lead in peeling paint? I am a hobby chemist owner of a Clinical Research Investigative Site. Please tell me if this site is only for professional chemists. If so, I will cancel my registration.

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    $\begingroup$ The best way would be by a hand held x-ray fluorescence instrument. $\endgroup$ – MaxW Mar 19 at 20:54
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    $\begingroup$ Lead test strips are available in hardware stores where I live and I think they are widely available. I do not know their limit of detection. $\endgroup$ – Ed V Mar 19 at 21:15

This site is not specialized and reserved to professional chemists. On the contrary. A lot of teenagers are using it every day.

Now if you want to identify lead in a dry paint, you may burn it in the flame of a Bunsen burner, and save the ashes. They contain a mixture $\ce{Pb + PbO + Pb3O4}$. Then dissolve the ashes in nitric acid (concentrated $\ce{HNO3}$ diluted with its own volume of water). Filtrate the insoluble part. Dilute the filtrate still more, by adding an equal volume of water. This gives you a lead nitrate solution, with which you carry out the following tests. Add some $\pu{1 M}$ $\ce{HCl}$ to a part of the obtained solution : it should produce a white precipitate of $\ce{PbCl2}$, if the solution contains some lead ions. Or add some $\ce{KI}$ solution : You would obtain a yellow precipitate of $\ce{PbI2}$, if the solution contains lead. The reactions are : $$\ce{Pb(NO3)2 + 2 HCl -> PbCl2(s) + 2 HNO3}$$ $$\ce{Pb(NO3)2 + 2 KI -> PbI2(s) + 2 KNO3}$$ A further proof is obtained by heating the solution containing the yellow deposit of $\ce{PbI2}$, because this substance gets redissolved at $\pu{100°C}$. And after slow cooling, $\ce{PbI2}$ will precipitate back and it looks like wonderful golden plates, floating in the liquid. It is amazing. If these precipitate do not occur, there is no lead in your paint.


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