【国外标准】 Standard Practice for the Determination of 237Np, 232Th, 235U and 238U in Urine by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Gamma Ray Spectrometry. (Withdrawn 2015)

This practice may be used as part of a bioassay program for workers potentially exposed to nuclear material by measuring 237Np, 232Th and 235U and 238U in their urine samples. ICP-MS has been used to analyze for many actinides in high-level radioactive wastes (1) , in soils (2) as well as uranium in urine (Test Method C1379). 237Np and 239Pu analysis by ICP-MS in bioassay samples has also been reported (3). Several days counting times are required for alpha-particle analysis of 237Np, 232Th and 235U and 238U whereas ICP-MS requires only four minutes per sample. Alpha-particle counting methods for neptunium may also require the use of 239Pu as a radiotracer for determination of chemical yield. ICP-MS sensitivity limits and isobaric interferences preclude accurate determination of 239Pu, 241Am and 234U at levels present in the urine samples. 234U may be estimated from the 235U: 238U ratio by inference.1.1 This practice covers the separation and preconcentration of neptunium-237 (237Np), thorium-232 (232Th), uranium-235 (235U) and uranium-238 (238U) from urine followed by quantitation using ICP-MS. 1.2 This practice can be used to support routine bioassay programs. The minimum detectable concentrations (MDC) for this method, taking the preconcentration factor into account, are approximately 1E-2Bq for 237Np (0.38ng), 2E-6Bq for 232Th (0.50ng), 4E-5Bq for 235U (0.50ng) and 6E-6Bq for 238U (0.48ng). 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.