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140Ba is a fission product of 235U and decays to 140La. Analytical method of uranium in geological and environmental samples was investigated by using 140La from 235U and the correction factor of 140La. For the method validation, three kinds of NIST SRMs were chosen and irradiated at the HANARO research reactor. The first and second measurements for the detection of 140La were performed, and the U content in SRM samples can be determined by two different La concentrations. The relative errors are within 10% of U values in the SRM samples. This method is applied for a NIST SRM 1648a-Urban Particulate Matter, which has no certified value. The measured value of U in SRM 1648a is 4.90 ± 0.20 mg/kg. [ABSTRACT FROM AUTHOR]

The toxicity, bioavailability, and mobility of the toxic element arsenic (As) vary with oxidation state and the chemical environment. Determining the precise fraction of individual As species as well as the total As content in various matrices is essential for evaluating the potential risk of As contamination. We present a synchrotron X-ray absorption spectroscopic study to characterise As species in a total of 14 different matrix certified reference materials (CRMs) and candidate materials of Korea Research Institute of Standards and Science (KRISS) include sediments, ash, ore tailings, seafood, commodity plastics, and cosmetic products. The validity of the method was evaluated by comparison with the results obtained using routinely applied extraction-based sample preparation and ion chromatography-inductively coupled plasma mass spectrometry for speciation analysis. Our study of the As K-edge fine structure with linear combination fitting revealed details of both the composition and distribution of As species in intact solid samples. The key advantage of the present method is its capability to selectively and non-destructively probe As species with minimal risk of species transformation, thus complementary to more popular extraction-based analytical methods. Depending on the sample matrices and origins the investigated CRMs showed distinct As species compositions, the spatial distribution of which was also investigated. This study proposes that X-ray absorption measurement has the potential to determine the native fractions of individual elemental species. [ABSTRACT FROM AUTHOR]

We report comprehensive elemental composition studies on the average urban airborne particulate matters (PMs) collected in the Greater Seoul area, Korea, in 2019 to identify regional and chronological characteristics of the sample as a candidate for certified reference material (CRM), using k0-based single comparator instrumental neutron activation analysis (k0-INAA). The method was successfully validated by comparing the analysis result of a similar matrix CRM (SRM 1648a urban particulate matter) of National Institute of Standards and Technology, USA, with corresponding certified values. The same methodology was applied to determine various elements in candidate environmental materials for future CRM development, including the urban PMs and incineration ashes, to investigate the possibility of using k0-INAA for certification of relevant reference materials. In total, 46 elements in the urban PM sample were analyzed and their concentration levels were compared with the urban PMs collected in the 1970s in St. Louis, USA. Urban PMs of Korea Research Institute of Standards and Science in 2019 contain significantly lower levels of hazardous elements, such as As, Cd, Cr, Hg, and Pb, as compared to those of the 1970s, which can be attributed to the reduced air pollution by environmental regulation and technological innovation. The potential major source of urban airborne PMs was also discussed. [ABSTRACT FROM AUTHOR]