inductively coupled plasma-optical emission spectroscopy (ICP-OES),5 and inductively coupled plasma-mass spectrometry (ICP-MS).6 (The references cited in this paragraph are intended to document the historical progression of the analysis technique, and are not intended to represent the state of the art of current technology.)

Based on committee member’s own expertise and knowledge of these techniques and familiarity with the recent literature, each of those instrumental methods has advantages and disadvantages. AAS is a single-element technique (one element at a time can be measured) that is limited in the overall number of elements that can be determined, although the elements of current interest for CABL can be determined. It also suffers from limited dynamic (working) range and is prone to interferences due to the sample matrix. NAA requires ready access to a nuclear reactor. SSMS has an advantage in that it requires minimal sample preparation; however, reliable quantitative analysis with SSMS is difficult. SSMS instrumentation also is not widely available. WDXRF spectroscopy suffers from inadequate limits of detection and has been used primarily for qualitative or semi-quantitative analysis.

ICP-MS has a sensitivity advantage over optical techniques, such as AAS and ICP-OES, and has a greater dynamic range than AAS. The major drawback of ICP-MS is that the lead sample matrix can suppress the element signals and can deposit on the sampling cone; this reduces ion throughput and yields erratic results.7 That drawback can be avoided by precipitating the lead with sulfuric acid before ICP-MS analysis. However, the added precipitation step increases overall sample preparation time and lowers the precision and accuracy of the element measurements.

INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTROPHOTOMETRY

The analytical characteristics of ICP-OES make it a useful technique for metal determinations.8 A typical ICP-OES instrument has the following components:

5  

Peters, C. A.; Havekost, D. G.; and Koons, R. D. Crime Lab. Digest 1988, 15, 33; Schmitt, T. J.; Walters, J. P.; and Wynn, D. A. Appl. Spec. 1989, 43, 687; Peele, E. R.; Havekost, D. G.; Peters, C. A.; and Riley, J. P. USDOJ (ISBN 0-932115-12-8), 57, 1991.

6  

Koons, R. D. Spectroscopy, 1993, 8(6), 16; Suzuki, Y. and Marumo, Y. Anal. Sci. 1996, 12, 129.

7  

Dufosse, T. and Touron, P. Foren. Sci. Int. 1998, 91, 197; Jarvis, K. E.; Gray, J. L.; and Houk, R. S. Inductively Coupled Plasma Mass Spectrometry, Blackie & Son: London, 1992.

8  

Veale, N. P.; Olsen, L. K.; and Caruso, J. A. Anal. Chem. 1993, 65 (13) 585A; Alcock, N. W. Anal. Chem. 1995, 67 (12) 503R; Methodology, Instrumentation, and Performance, Boumans, P. W. J. M., Ed.; Inductively Coupled Plasma Emission Spectroscopy Part 1. John Wiley & Sons: New York, NY, 1987.



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