Instrumental neutron activation analysis is routinely used at the MURR to quantify selenium in prospectively-collected biologic
markers including blood serum and toenails. These specimens are typically collected from well-defined cohort populations participating
in investigations assessing selenium intake and incidence of chronic disease endpoints. These epidemiological investigations,
whether observational (case-control) or clinical (intervention), typically generate thousands of samples. The purpose of this
paper is to assess, through evaluation of quality control results, if the achievable accuracy and precision in the measurement
of selenium using NAA is adequate to determine a relative risk of 1.2 at high confidence in epidemiological studies.