engleski

Advantages of the k0-INAA for characterization of soil samples

For soil elemental characterization, nuclear analytical methods may have several advantages compared to other spectrometric techniques. In this study, instrumental neutron activation analysis (INAA) is presented in terms of its sensitivity, versatility and high reliability. Neutron activation analysis (NAA) is a nuclear analytical technique that utilises the specific properties of nuclear reactions, thereby enabling simultaneous determination of numerous elements in a sample without its decomposition. Due to very small matrix interferences during neutron-sample interactions, NAA is one the most prominent analytical technique for the determination of rare earth elements and actinides in soil samples. The idea of using the k0-method of instrumental neutron activation analysis (k0-INAA) for analytical purposes appeared in the early 1970s, where the absolute nuclear data are replaced with k0-factors that are experimentally determined. It uses Au as the standard (in form of an Al-0.1%Au alloy) irradiated together with a sample. The k0- method at the Department of Environmental Sciences of the Jožef Stefan Institute (IJS) has been introduced in the middle 1990s and validated, and since then it has been used for routine analyses for determining micro and trace elements in different environmental samples using the 250 kW TRIGA Mark II research rector. In addition, the k0-INAA technique has been accredited according to the ISO/IEC 17025 for determining elemental composition in environmental samples since 2009. In this work, the k0-INAA technique was applied for the determination of rare earth elements and actinides in samples of sewage sludge-amended soil. The results revealed that concentrations of La, Ce, Nd, Sm, Eu, Tb and Yb varied from 17.4 to 59.7, 35.0 to 158.0, 17.1 to 54.8, 3.2 to 9.4, 0.7 to 2.0, 0.4 to 1.2 and 1.5 to 4.0 mg kg-1 dry weight, respectively. Concentrations of U and Th were within limits from 1.5 to 4.1 and 5.6 to 27.3 mg kg-1 dry weight, respectively. According to ISO/IEC 17025 accreditation certificate LP-090 given by Slovenian Accreditation for the k0-INAA technique ; all results are inside the accreditation ranges, which for above mentioned elements varied from 0.005 mg/kg to 1000 mg/kg. In conclusion, the low limit of detection and the combined standard uncertainty up to 10% of the measurement results confirmed the high sensitivity and reliability of the k0-INAA for such applications.

Rare earth elements ; Actinides ; Soil ; k0-INAA ; TRIGA reactor

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