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Chemical Stability and Compatibility - Lead (Pb) instability in HNO3

 
I am using CGPB1, a 1000 microgram/ml Pb standard, and I made up a set of standards to test for Pb in some water samples. My standards were 1, 0.5, 0.1, and 0.01 ppm. I acidified them with 2% v/v HNO3, the remainder being DI water. The standards seem to be extremely unstable, I can't get even a single sample run through my ICP with them. Any thoughts?
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admin Total posts: 529

This behavior for Pb is unusual, as your matrix is appropriate and the preparation seems very straightforward. We assume that your standards are sulfate-free, as SO4 can compromise Pb stability. A few questions would be: 1) is Pb the only element present in the standards?, 2) do you obtain good results initially, followed by decreases in Pb intensities?,  3) are you using ICP-OES or ICP-MS?, 4) what emission lines or masses are you monitoring, and are the results consistent for all lines/masses? It’s possible that with additional information we may be able to offer more significant assistance to help troubleshoot this issue.

Posted: 09/02/18 23:18:23

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