Neutron Activation Analysis for processed animal proteins and insect meals characterization

Neutron activation analysis (NAA) is a very useful analytical technique used for determining elemental concentrations in a large variety of different matrices. It is based on neutron irradiation of samples therefore a source of neutrons such as a nuclear reactor is required. The neutron irradiation generates radioactive isotopes in the sample and radioactive decay paths for each element are well known. By using germanium detectors and certified standard materials the generated emissions spectra give information about the concentrations of the elements within the samples. The penetrating nature of incident neutrons and resultant gamma rays, the technique provides a true bulk analysis. As different radioisotopes have different half-lives, counting can be delayed to allow interfering species to decay eliminating interference. This analytical method is useful multi-element analyses with minimum detection limits in the sub-ppm range providing an elemental fingerprint of the analyzed sample which can be used for the specific recognition of an unknown sample. In this work NAA was used to study systematic differences in the elemental composition of different zootechnical meals, including processed animal proteins (PAPs) of different species and insect meals. Chemometrics was exploited for variables’ screening and data treatment. The scope of this work is to provide a very specific characterization of meal products that could be fraudulently add to compound feed in view of a species-specific recognition of unknown meals.