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Arsenic and Zachary Taylor Two researchers at the Department of Energy's Oak Ridge National Laboratory (ORNL) provided information that helped officials of the Commonwealth of Kentucky resolve the question of whether President Zachary Taylor was a victim of arsenic poisoning. Frank Dyer and Larry Robinson of ORNL's Analytical Chemistry Division analyzed two samples of hair and two samples of fingernails by instrumental activation analysis. Neutron irradiation of arsenic yields 76 As, which decays with a 26-h half-life and emission of a 559-KeV gamma ray (42% yield). The samples, which ranged from 2.7 mg for the smaller hair sample to 12.3 mg for the larger nail sample, were not chemically cleaned before analysis. They were placed in cleaned polyethylene "rabbits" (irradiation capsules) and irradiated for 1 min in a thermal neutron flux of 4.61 x 10 13 n cm~ 2 s _1 . Gamma spectra were acquired periodically with two Ge(Li) detectors over a three-day interval following the irradiation. The source-to-detector distance was 40 mm, and the detectors had resolutions of ~ 2.1 KeV fwhm and counting efficiencies of 1% for the 559-KeV photon. No photopeaks of arsenic were observed in any of the specimens. Limits of detection for As were - 2 |ig/g sample. Three empty, cleaned rabbits were also irradiated, and their inner walls were swabbed with damp cotton. Each swab was counted to test for the presence of arsenic, and none was found. To verify the accuracy of their results, Dyer and Robinson also analyzed SRM 1633a, which contains 145 ±15 ppm As. Neutron activation analysis of this SRM gave an observed value of 136 +7 ppm As. As a result of these tests, Dyer and Robinson reported that arsenic, if present, had a concentration of
