Ida Di Carlo asked about analyses of trace bromine and I just wanted to mention that we really should be using the Br Ka line which isn't interfered with by Al.
(https://smf.probesoftware.com/oldpics/i61.tinypic.com/35ndkww.jpg)
However, it is a relatively high energy line and, especially on the Cameca instrument, really needs a better detector such as the proposed tandem detector system described here:
http://smf.probesoftware.com/index.php?topic=193.msg1831#msg1831