Aluminum, Beryllium, and Chromium Interferences

Angie, a QA-QC manager, was struggling with some Aluminum results, as well as those from Beryllium and Chromium. Her reported results for these elements seemed to always fall just outside of the warning limits. She had guessed that part of this problem might come from fluctuating Silica levels in her water, but she wanted to be sure. Angie also asked about any other elments that might interfere with Aluminum, Beryllium, and Chromium.

	RE: Aluminum, Beryllium, and Chromium Interferences Dear Angie,      Although I do not know the specific lines you are using, I would guess that they are the 308.215 nm Al line, the 313.042 nm Be line, and the 205.552 nm Cr line, since these lines are most often used in EPA methods. These lines experience direct spectral interference for the V 308.211 nm line upon Al, the 313.027 nm V line upon Be, and the 205.564 nm Mo line upon Cr. The strongest interferences are the V upon the Al and Be. The Mo interference is not as significant. In addition, Si does not interfere with any of these lines at Si levels well above that expected in water (~100 ppm). The direct spectral interference would cause the data to be on the high side.      I should also mention that V, Mo, and Mn have lines where background correction is made on standard solutions causing the standard line intensity to be low. This yields high results on samples that have little to no interferring elements. If you have any other questions, don't hesitate to ask.     Paul R. Gaines, Ph.D. Serving you in chemistry