Page 146 - Inorganic Mass Spectrometry - Fundamentals and Applications

136 Ol~sik

digestion is faster than hot plate methods. However, Teflon vessels can become
contaminated. It is useful to keep a history of the Teflon vessels and to assess
method bld levels by processing a blank through the entire dissolution process.

aterials Analysis

ICP-MS has been used for the analysis of many materials, including alloys, steels,
nuclear materials, ceramics, superconductors, plastics, polymers, and catalysts.
Semiquantitative analysis by ICP-MS is often a convenient method to screen
samples for trace elements and impurities. Measurement of impurities can be
complicated by sample matrix-dependent degradation of sensitivity, particularly
of
if the samples contain high concentrations heavy elements that create extensive
space-charge-induced ion trans~ssion losses. Matrix mat~hing is complicated by
the need for ultrapure materials.

Metals and Alloys

Even sub-ppm levels of some elements can affect properties and processing of
steel and other alloys. The analysis of low- and high-alloy steels for environmen-
tally important elements (Cd, Hg) as well as elements that affect the steel (Sb
and Bi, for example) has been discussed [343]. ICP-MS has been used for semi-
qu~titative and quantitative measure~ent of Gd, Sm, and Th in zirconium alloys
~3441.
ICP-MS has also been used to measure trace elements in archaeological
native silver artifacts C3451 in order to identify their geographical origins, The low
detection limits provided by ICP-MS allowed analysis trace elements on 3 to 15
of
has
mg of sample. The passivation of alloy steels using acid solutions been studied
by XPS measurements of the solid in combination of ICP-MS analysis of the
passivation solutions [346,347]. When bullets are c~shed on impact, striations
cannot be used for identification. The percentage of antimony, trace element
composition, and lead isotope ratios in bullets was measured for forensic evidence
[348]. The lead isotope ratios were found to be the most usefbl evidence.
To analyze metals and alloys directly without dissolution, both spark abla-
tion l3491 and laser ablation [6 1,21 l] dry aerosol generation systems have been
used to introduce samples into an ICP-MS. These approaches often require
ma~x-matched standards, although several active research groups are focusing
of material ablated depends
on techniques to reduce that requirement. The amount
on the sample type. Fractionation of elements can also be a problem, depending on
of
the sample, the laser fluence, the laser wavelength, and the number laser pulses
used to sample from a fixed location. Volatile elements that are segregated in
the samples appear to be most prone to fractionation problems [61].