A method for mesoporous supraparticle synthesis on superamphiphobic surfaces is designed. Therefore, supraparticles assembled with nanoparticles are synthesized by the evaporation of nanoparticle dispersion drops on the superamphiphobic surface. For synthesis, no further purification is required and no organic solvents are wasted. Moreover, by changing the conditions such as drop size and concentration, supraparticles of different sizes, compositions, and architectures are fabricated.

One major challenge in nanomaterial analysis, especially in complex environmental matrices, is the unambiguous differentiation between natural and engineered nanomaterials (ENMs). Particularly with regard to the investigation of ENM's/engineered nanoparticle's (ENPs) fate, analytical methods are needed allowing for tracing and sensitive quantification. Several ENPs are metal-based and contain elements being omnipresent in environmental matrices (e.g., Al, Ti, Zn, Fe and non-metal Si) - hence, high background levels of these elements are expected, compromising sensitive detection. In this work we developed successfully a combined approach of stable isotope labeling (tracing) and reverse postchannel species-unspecific on-line isotope dilution (quantification) in combination with AF4/sector-field ICP-MS (AF4/ICP-SFMS). The approach was successfully applied to iron oxide nanoparticles isotopically enriched in Fe-57 coated with a SiO2 shell (Fe-57@SiO2 ENPs). Upon method development and validation the Fe-57@SiO2 ENPs were spiked into a filtered re-suspended river sediment-slurry matrix for proof-of-concept. Our approach allowed for unambiguous tracing of the Fe-57@SiO2 ENPs among natural iron colloid fractions as well as simultaneous sensitive quantification via reverse on-line ID despite high "natural" iron background. A limit of detection of 2.4 mu g Fe L-1 and a limit of quantification of 7.8 mu g Fe L-1 in real matrix was achieved. Furthermore, a good reproducibility in terms of peak areas was obtained (0.4-3.0%); the RSDs for elution times vary between 0.1 and 0.7%. To the best of the authors' knowledge, for the first time a reverse post-channel on-line isotope dilution AF4/ICP-SFMS approach in combination with isotopically labeled Fe-57@SiO2 ENPs was developed, allowing for (i) unambiguous tracing, and simultaneous (ii) sensitive quantification of the Fe-57@SiO2 ENPs within a sediment slurry matrix in the presence of natural iron colloid fractions. Based on the experience gained in this work, we feel certain that the approach is deployable to further stable isotope labeled metal-and nonmetal-based ENMs and shows great potential in ENMs studies