We used triple-quadrupole and high-resolution inductively coupled plasma-mass spectrometry (ICP-MS) in single-particle mode to characterize the food additive E171 (titanium dioxide, TiO2) in chewing gum, chocolate candy, and cake decoration in the same sample extracts. Then, we spiked TiO2 particles (with similar characteristics as E171) to milk as an example of a calcium-rich matrix. The obtained particle size distributions with both techniques were highly similar in terms of shape and median and mean diameters. Median diameters were in the range of 123 to 209 nm and mean diameters from 146 to 223 nm. In addition, they were in agreement with results obtained by scanning electron microscopy and asymmetric flow field-flow fractionation coupled to multi-angle light scattering and ICP-MS. Repeatable determination of number-based particle size distributions was possible with both ICP-MS techniques even in a calcium-rich matrix showing that both instruments were similarly efficient in resolving the Ca interferences. The combination of spICP-MS with microscopy and TiO2 recovery allowed validating the methods and identifying the presence of aggregated/agglomerated particles in one sample. For the TiO2 powder and the two remaining food products, recoveries were higher than 60%. Both instruments are fit for purpose even if the analyses were performed with differences in detector mode, dwell times, and calculation tools. This shows that both techniques may be used as long as operating conditions are optimized and applicability range is defined.
Bibliographical noteFunding Information:
We thank Agilent Technologies for providing the Agilent 8900 instrument and Raquel Larios and Michiko Yamanaka for their support. The work was supported by the Danish Veterinary and Food Administration. We thank Georges Favre and Nicolas Feltin from LNE for their help preparing this manuscript and Caroline Oster for the help with sample digestion. The frosting sample and the corresponding SEM data are used with courtesy of SCL. We further thank the JRC Nanomaterials Repository for supplying the TiO materials NM-100 and JRCNM10200a. 2
The authors received support from the French Metrology Network for this work. Sara López-Sanz also received support from the Ministry of Economy and Competitiveness of Spain for her pre-doctoral contract BES-2014-069095 and for her pre-doctoral mobility grant EEBB-I-2018-13021.
© 2021, The Author(s), under exclusive licence to Springer Nature B.V.
- Single-particle ICP-MS
- Titanium dioxide