Development of a rapid micro-Raman spectroscopy approach for detection of NIAS in LDPE pellets and extruded films for food packaging applications

Identification and quantification of Non Intentionally Added Substances (NIAS) at low concentrations and eventually their distribution on Low Density Polyethylene (LDPE) films is an important issue. As Raman spectroscopy techniques are innovative and sensitive analytical methods and do not require pretreatment and manipulation of the sample, these were used for the identification of NIAS in LDPE pellet and films, which are commonly used for food packaging applications. The aggregation state of NIAS in LDPE were observed by Raman imaging with micrometric resolution. Four main NIAS compounds were identified in granule and film surfaces by confocal Raman spectroscopy: calcite (CaCO3), calcium sulphate (CaSO4), polystyrene (PS) and titanium dioxide (TiO2) in anatase form. By a semi-quantitative evaluation of the inorganic NIAS, 9.93 mg/kg of CaCO3, 1.62 mg/kg of CaSO4 and 0.17 mg/kg of TiO2 were estimated. The experimental findings achieved by Raman analysis were confirmed by the results obtained by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Moreover, the toxicity of the identified compounds was examined according to the Cramer rules.