Quality Assurance of Potential Radioanalytical Methods for ¹⁴C in Environmental Samples

Today, the measurement of C-14 in environmental samples is of particular interest, as it enables the assessment of the impact caused by nuclear activities and the fossil fuel industry on the environment. In order to assure the quality of C-14 measurement results, the strategy to enlarge the validation of three radioanalytical methods in environmental samples using liquid scintillation spectrometry-the direct counting of water, bubbling of water and combustion of solids-is presented. Due certain difficulties, such as the lack of quality control materials and the scarcity of proficiency test and intercomparison exercises, especially in solid samples, a set of water and soil samples were prepared for the purpose by tracing them with known quantities of a C-14 standard solution at two activity levels. Aliquots were subjected to the corresponding method and their activity concentration was calculated. Finally, uncertainty, detection limit, accuracy, precision, repeatability and linearity were analysed. The acceptance criteria for the quality parameters were previously established according to ISO 13528:2015 standard and Eurachem Laboratory Guide to Method Validation. In all the methods, the studied parameters fall within the acceptance range, so they are validated. The quality of the results in real samples is controlled through field validation.