Neutron Activation Analysis for the characterization and discrimination of processed animal proteins and insect meal

Neutron activation analysis (NAA) is a very effective analytical technique for the determination of the elemental composition in a large variety of matrices. It is based on neutron irradiation of the samples therefore a source of neutrons such as a nuclear reactor is required. The neutron irradiation generates radioactive isotopes related to the constituents of the matrix. By using germanium detectors and certified standard materials the generated emissions spectra give information about the elemental composition. The technique provides a true bulk analysis then no sample dissolution is necessary and problems related with contamination or losses are therefore avoided. As different radioisotopes have different half-lives, counting can be delayed to allow interfering species to decay eliminating spectral interference. NAA allows minimum detection limits in the sub-ppm range providing an elemental fingerprint of the analyzed sample which can be used for a deep characterization, for provenance and discriminating studies. In this work NAA was used to study systematic differences in the elemental composition of different zootechnical meal, 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.