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Neutron Activation Analysis Facilities

Instrumental Neutron Activation Analysis (INAA) at NIST

Instrumental neutron activation analysis (INAA) is a nuclear analytical technique for measuring the concentrations of large number of elements in a single sample and can be applied to the analysis of a wide variety of sample types. INAA involves exposing the sample (along with prepared standards and appropriate quality control materials) to a field of neutrons. This exposure causes most of the elements within the sample to become radioactive. The energy of the radioactive emission allows identification of the element and the intensity of emission is proportional to the mass of that element.

At NIST, INAA is routinely used to determine concentrations of as many as 40 elements in geological, botanical, and human and animal tissue materials. INAA is one of the techniques used to measure elemental concentrations in NIST Standard Reference Materials (SRMs). Several SRMs for which INAA was used to provide trace element concentrations for certification are shown in Figure 1. (For additional information on SRMs see http://ts.nist.gov/ts/htdocs/230/232/232.htm )

Standard Reference Materials

Figure 1. Standard Reference Materials for which elemental concentrations were determined by Instrumental Neutron Activation Analysis.

Radiochemical Neutron Activation Analysis (RNAA) at NIST

Radiochemical neutron activation analysis (RNAA), like INAA, involves exposing the samples to a neutron field to create radioactive emitters. However, RNAA involves chemical separation of the sample to isolate one or more elements from the sample matrix. Isolation of the element is performed to eliminate any spectral interferences and to lower the background.

Using RNAA it is possible to achieve lower detection limits than are obtained using conventional INAA. RNAA has been used to analyze a wide variety of sample types. For example, RNAA has been used to determine the concentrations of tin and platinum in human liver tissue, and to determine cadmium and mercury in botanical reference materials.

For additional information on INAA and RNAA at NIST contact Dr. Robert R. Greenberg, e-mail address: greenber@micf.nist.gov
Last modified 30-August-2001 by website owner: NCNR (attn: Bill Kamitakahara)