Page 138 - Inorganic Mass Spectrometry - Fundamentals and Applications

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analysis can be used to identify sources of lead. In one study [246], people with
low lead concentrations in the United Kingdom had 206PbPo7Pb isotope ratios of
1.13 rt: 0.01. Lead uptake from drinking water (source isotope ratio 1.18) in parts
of Scotland was found to contribute 60% to body lead. Lead from gasoline in inner
to 40% of lead
London (source isotope ratio approximately 1.07) contributed 30%
in inner London children.
The accuracy of autopsy tissue elemental analysis has been assessed [247].
Results indicated that differences in elemental concentrations depend on age.
Tissue of patients in chronic renal failure and treated by hemodialysis can accu-
mulate higher concentrations of Cr and Al. Black particles observed in a spleen
fragment from a patient who had previously had a replacement were found by
hip
ICP-MS to contain high titanium concentrations [248].
Trace metals have been measured in various tissues by ICP-MS to investi-
gate Alzheimer’s disease [249-2521. Various sample preparation and processing
approaches have been used, including flow injection analysis and extraction, Al,
Si, and Sn levels were reported to be higher than in healthy tissue, whereas zinc
and selenium concentrations were lower. In the temporal cortex there were also
reductions of cesium and cerium concentrations. The mechanisms responsible and
the key elements remain incompletely understood.
Laser ablation ICP-MS can be used to obtain spatial maps of elemental
composition in tissues. In one study [253], LA-ICP-MS was used for “elemental
tagging” of fish scales, rat kidney cross sections, and examination of the blood/
bone interface in a pig femur. Ca and Mg were used as “natural” internal
standards.
A variety of elements have been measured in fish tissue to determine the
into
cause of fish kills and to assess water quality. Slurry samples were introduced
the ICP by using electrothermal vaporization in one report [254] with isotope
dilution based determination of Gu, Zn, Cd, and Pb. Sample preparation was
simplified by using slurries rather than complete dissolution. Electrothermal
vaporization can be used to reduce spectral overlaps due to molecular ions that
~ontain oxygen. The sample can be dried in the furnace before vaporization of the
analytes. The time-dependent vaporization can also be used to reduce some matrix
effects. Isotope dilution improves precision and accuracy of the analysis. The
uptake and organ-dependent accumulation of cadmium in carp have also been
investigated by ICP-MS analysis [255].
Platinum-based compounds are commonly used as cancer treatment agents.
Ph~acokinetic studies of these antitumor drugs require ultratrace analysis.
Electrothermal vaporization ICP-MS provides low detection limits for small
samples [256]. High-performance liquid chromatography with ICP-MS detection
allows speciation of platinum compounds in tissues [256]. LA-ICP-MS can be
used to study the dis~bution of platinum in tissues and tumors [256]. Natural
levels of Pt are below typical quadrupole ICP-MS detection limits [257].