SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

M4
ANALYSIS OF TRACE METAL CONTENT IN HUMAN HAIR USING LASER ABLATION
INDUCTIVELY COUPLED PLASMA MASS SPECTROSCOPY (LA-ICP-MS)
Wat L. Harden I * and Robyn Hannigan 2 ; IArkansas State University, Dept. of Biology, P.O. Box 419, State
University, Arkansas 72467, 2Arkansas State University, Dept. of Environmental Sciences, P.O. Box 419,
State University, Arkansas 72467
Measuring the trace element content in human hair is traditionally done by acid digestion and analysis by
atomic absorption or Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Acid digestion of
samples can introduce contamination, which then lowers the accuracy ofthe analytical method. In addition
to the contamination issues, acid digestion under trace metal clean conditions can be labor intensive and
costly. Laser ablation (LA) is a sample introduction technique that, when combined with the ICP-MS, has
the potential to provide accurate metal concentration data.
Here we present method development data comparing traditional acid digestion liquid-based ICP-MS to
LA-ICP-MS on two certified hair standards (International Atomic Energy Agency Reference Material
Human Hair IAEA-085 and The People's Republic of China Reference Material Human Hair GBW 07601)
and laboratory internal standard (USGS basalt standard BCR-2). The two sample preparation techniques
that were compared were acid-digestion and solid sampling via laser ablation. Internal standards were used
to calibrate both liquid and solid analysis techniques to monitor instrument drift (liquid - 115 In; solid-total
Si in ppm). The concentrations of Fe, Zn, Ca, Cu, Mg and Mn of each sample were compared, using the
known concentrations from each hair standard.
Following the analysis of the BCR-2 standards and samples, we found that LA-ICP-MS analysis is
reproducible only within an error of 20%. This could be due to matrix interferences (organic v.s. silicate)
which were not corrected for in this preliminary study. Overall laser ablation is an excellent tool for trace
metal analysis providing accurate element ratio data (eg; CulCa) but not concentrations at this time. Future
studies will focus on the development of a matrix matched solid standard mitigating matrix interferences.
Keywords: Trace Analysis, LA-ICP-MS, Hair
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