INAA as an analytic technique:

Advantages:

Disadvantages:

! number of elements - Sixty-seven common and rare earth elements become radioactive when exposed to the neutron flux in a reactor. Of these 67 elements, over 50 can be identified and measured quite readily.

 

! multi-element - By using different combinations of irradiation and decay times, it is possible to measure a large number of elements from isotopes of different activities and half-lives. A standard analysis package can routinely analyze for 32 elements in a single sample. INAA is the only procedure that can simultaneously measure so many elements.

 

! highly sensitive - The method permits measurement of all detectable elements with great sensitivity; many elemental concentrations are measurable in parts per million (ppm) or parts per billion (ppb).

 

! elemental analysis - determines element regardless of chemical form (ferric vs. ferrous). This can be either an advantage or a disadvantage.

 

! non-destructive - Unlike other techniques, the sample is not destroyed by the analysis, and can be re-analyzed if necessary.

! bulk analysis technique - whatever is pulverized and irradiated contributes to the gamma spectrum. INAA does not provide spatial resolution or imaging capabilities. Thus, it is often wise to combine INAA with visual methods of analysis, such as SEM or petrography, to help determine what is contributing to the elemental signature of a sample.

 

! expensive - in the past, INAA was difficult to obtain and expensive. However, several research reactors provide irradiation services and have brought the price down to an affordable level.

 

! radioactive - samples analyzed using INAA become radioactive waste and usually cannot be returned to the researcher.

Oregon State University Archaeometry Lab