Page 297 - Inorganic Mass Spectrometry - Fundamentals and Applications

Analysis o~~onconduc~ive Sample Types 283

Radio frequency glow discharge mass spectrometry (rf GD-MS> spectrum of
the lead components in an NIST 612 Trace Elements in Glass sample; 204Pb concentration,
540 ppb. (From D. C. Duckworth, unpublished results.)

lated to be 16 ppb, This value is very competitive with that achieved in metals analy-
dc
sis under similar acquisition conditions using power. Finally, Gibeau and Mar-
cus [67] have shown that the resultant crater shapes produced in the rf sputtering
of ceramic materials do not differ appreciably from those of metals, suggesting a
number of oppo~u~ties in depth profile analyses (albeit at much slower rates).
The analysis of nonconductive (usually oxide) powder samples touches a
very diverse set of industrial applications ranging from geological specimens to
precious metal containing automotive catalysts. As would be expected from the
detailed discussions in Sec. 7.2, the analysis of powders is a great analytical chal-
lenge. In fact, the analysis of samples originating in powder form does not benefit
rf powering; the reason is straightfo~ard.
to the extent that one might expect from
Although the use of rf powering permits the analysis of pressed oxide materials
without the need for a conductive metal binder (as required for dc GI> operation),
of the use of “gettering” binders is lost. Thus, the mass
the much discussed benefits
as a result of ad-
spectra of directly compacted samples are inherently complicated
In
this
ventitious water and trapped gases in the pressing process. case, direct com-
parison with the use of dc powering for getter-bound compacted samples is a rea-
sonable endeavor.