Characterisation and quantification of titanium dioxide nanoparticles in food simulants by single particle inductively coupled plasma-tandem mass spectrometry using a high efficiency sample introduction system

Abstract

This article reports the development of a novel method based on single particle inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) using a high efficiency sample introduction system (HESIS) for the characterisation and quantification of titanium dioxide (nano)particles (TiO2 NPs) in food simulants. The use of the mass-shift mode (O2 + H2 as a mixture reaction gas) avoids the isobaric interferences of 48Ca isotope hence allowing accurate characterisation of TiO2 NPs in complex matrices such the foodstuffs. Two HESIS (APEX™ Q and APEX™ Ω) were compared with the conventional ICP-MS/MS sample introduction system in terms of sensitivity and trueness for the detection of TiO2 NPs in various (organic) food simulants. APEX™ Ω proved to be an excellent approach to avoid matrix effects from food simulants and provided significantly lower limits of detection in size (LODsize) compared to the conventional introduction system. In order to avoid the saturation of the detector when detecting large TiO2 particles (> 300 nm), the analyses were carried out using the forced analogue detection mode and accurate characterisation of TiO2 NPs in terms of size and concentration was achieved, with an average LODsize of 20 nm over 3 days. This confirms the feasibility of this novel approach using an APEX™ Ω for the characterisation and quantification of TiO2 NPs in complex matrices such as the food simulants and its application to real-life studies regarding the migration of TiO2 NPs from food containers into the simulants.