Page 137 - Inorganic Mass Spectrometry - Fundamentals and Applications

Inducti~ely Coupled Plasma Mass Spectrometry 127

Comparisons of Certified and Measured
Concentrations in National Institute of Standards and
Technology (NIST-SRM) 2670 Urine Using Different
Internal Standards

~le~en~intemal standard Concentration (ppblnglrd)
As (target value) 480 2 21
Aslnone 626
AslGa 49 1
AsN 49 1
Cd (target value) 88 3- 3.4
CdRh 80
CdlAg 85
CdlIn 78
CdlSb 67
Pb (target value) 109 3- 3.7
Pb/Re 86
PbBi S so
Source: Ref. 232.

There are many examples of relatively straightforward use of ICP-MS for
in
the analysis of biological fluids. Antimony has been measured blood after a 14: 1
dilution [236]. Cesium serum levels were found to be elevated in patients with
alcohol dementia but not in Alzheimer’s disease patients [237]. Cobalt levels in rat
serum depended on the form of cobalt [238] ingested. Bismuth levels were
measured in human blood and urine by using a direct injection nebulizer [239].
Lead was measured in the blood and blood plasma of smelter workers and the
general population [240]. The measurement of trace elements in serum by ICP-
MS has been compared to results from neutron activation analysis and proton-
induced x-ray emission [241]. Semiquantitative analysis can also be used obtain
to
a rapid screening of samples [242].
In some cases ICP-MS now allows measurement of elements that previ-
ously were difficult or impossible to measure at low enough levels to set reliable
reference ranges for humans. Reference ranges for Li, B, MO, Sn, Sb, CS,
Pb, and Bi were reported [243]. Measurement of uranium levels in an unexposed
population has also been reported [244].

Biological Tissue
ICP-MS analysis of human tissue [245] has been described in several reports.
Microwave digestion was commonly used for sample preparation. Analysis of
tissues can provide information on essential elements as well as toxic elements.
Pb isotope ratios depend on the source of lead. Therefore, ICP-MS isotopic