First, is it correct to say that XRF measurement applies only to metals and transitional metals in the periodic chart? In otherwords, XRF can only be used to measure ppm levels of metals in solution etc. etc. For instance, zinc and aluminum could be measured with XRF.
What about a non-metal like boron ---- why can't XRF truly be used to measure concentration of boron.....especially when boron and zinc have somewhat similar first ionization energies?
Would boron be measured by mass-spec?? And how would that actually work?
From what I've seen, it appears that pretty much any element from Li upwards may be analyzed by X-ray fluorescence. I am under the impression, though, that most machines won't analyze for Li and Be. I did see one reference, though in which B in BN was subjected to soft X-rays and other excitations were noted that were not as a result of removal of one of the inner electrons. What was happening was also an absorption of X-rays causing excitation of a 2s valence electron to a p* excited state.
I think what they are talking about is something like this...
B 1s 2s 2 p _ __ __
B 1s 2s _ 2 p _ _ __
where the p* above is denoting an excited electron. However, I'm not sure if this would affect your ability to measure B by X-ray fluorescence, unless the effect produces a line that overlaps with something else or produces some other anomalous result.
X-Ray Fluorescence and Mass Spectrometry are discussed in relation to analyzing for boron. Sources are provided.