Standardization of technetium-99 by liquid-scintillation counting

Technetium-99 has been standardized by comparing its pulse-height response on a liquid-scintillation counter with that of another β-particle-emitting standard radionuclide. In this work, hydrogen-3, carbon-14, and cobalt-60 were used as the standards, and the results obtained agreed to within 0.32%. The mass of potassium pertechnetate was also measured by gravimetric techniques for the technetium-99 radioactivity standard solution. A half-life value of (2.111 +- 0.012) x 105 years is suggested. The estimated uncertainty is intended to approximate one standard deviation. (author)