Unique quality assurance aspects of INAA for reference material homogeneity and certification

Abstract

Instrumental neutron activation analysis (INAA) has become one of the primary analytical techniques for certification of elemental content in biological Standard Reference Materials (SRMs) at the National Institute of Standards and Technology (NIST). One important reason why INAA has become so widely used and valuable in the certification of NIST SRMs is that INAA has unique inherent quality assurance (QA) characteristics which provide the capability for accurate analysis and which often allow the analytical values obtained to be internally evaluated and cross checked. While the NAA technique has the general characteristics of most spectroscopic techniques, the specific characteristics include uniform activation, long and well-documented excited states, highly penetrating emitted radiation, and an excited state decay process which is statistically random in nature. These characteristics work together to provide an analytical technique which can provide highly reliable analytical results and is particularly suitable for the certification of major, minor, and trace elements in biological reference materials.