Measurement of arsenic in sectioned hair samples by instrumental neutron activation analysis

Abstract

In a recent Texas murder case, bundles of head hair from the female victim (aligned with all root ends together) were washed, cut into 7 mm sections, air-dried and weighed, activated in a nuclear reactor neutron flux, and then counted with a Ge(Li) detector/4096-channel gamma-ray spectrometer. In each of the 15 samples, the 559 keV gamma-ray peak of 26.3 hour⁷⁶As was measured. In the section closest to the scalp, an arsenic concentration of 107 ppm was found (cf. a “normal” level of about 1 ppm As). Barium ingestion was also possible so Ba was looked for, but not found. The victim's husband was found guilty of murder by chronic arsenic poisoning.