Characterisation of titanium dioxide (nano)particles in foodstuffs and E171 additives by inductively coupled plasma-tandem mass spectrometry using a highly efficient sample introduction system.

This study addressed primarily the characterisation and quantification of titanium dioxide (TiO) (nano)particles (NPs) in a large variety of commercial foodstuffs. The samples were purchased from local markets in Spain before the ban of TiO food additive (E171) in the EU. The analyses were carried out by inductively coupled plasma-tandem mass spectrometry (spICP-MS/MS) in mass shift mode (oxidation of Ti to TiO ( = 64)) and using a highly efficient sample introduction system (APEX™ Ω). This novel analytical approach allowed accurate characterisation of a large panel of TiO NPs sizes ranging from ∼12 to ∼800 nm without isobaric interferences from Ca isotope, which is highly abundant in most of the analysed foodstuffs. TiO NPs were extracted from foodstuffs using sodium dodecyl sulphate (0.1%, ) and diluted with ultra-pure water to reach ∼ 1000 particles signals per acquisition. All the analysed samples contained TiO NPs with concentrations ranging from 10 to 10 particles kg, but with significant low recoveries compared to the total Ti determination. A selection of samples was also analysed using a similar spICP-MS/MS approach with a conventional sample introduction system. The comparison of results highlighted the improvement of the limit of detection in size (12 nm) by the APEX™ Ω system, providing nanoparticulate fractions ranging from ∼4% (cheddar sauce) up to ∼87% (chewing gum), which is among the highest nanoparticulate fractions reported in literature using a spICP-MS approach. In addition, two commercially available E171 additives were analysed using the previous approaches and other techniques in different European laboratories with the aim of methods inter-comparison. This study provides occurrence data related to TiO NPs in common commercial foodstuffs but it also demonstrates the potential of the novel analytical approach based on APEX™-ICP-MS/MS to characterise nano-size TiO particles in complex matrices such as foodstuffs.