Single particle ICP-MS combined with a data evaluation tool as a routine technique for the analysis of nanoparticles in complex matrices

Detection and characterization of nanoparticles (NPs) in complex media as consumer products, food and toxicological test media is an essential part of understanding the potential benefits and risks of the application of nanoparticles. Single particle ICP-MS (spICP-MS) was studied as a screening tool for the detection and characterization of nanoparticles in complex matrices such as food and biological tissues. A data evaluation tool was created for the calculation of particle size, concentration and size distribution from the raw data. spICP-MS measurements were carried out on a standard quadrupole instrument as well as on a sector-field instrument. Performance characteristics were determined for four types of NPs. For the quadrupole instrument the size detection limits were 20 nm (Au and Ag), 50 (TiO2) and 200 nm (SiO2). For the sector-field instrument size detection limits are lower, 10 nm (Au). Concentration detection limits ranged from 1 ng L-1 for 60 nm Au NPs to 0.1 mu g L-1 for 500 nm SiO2 particles. The dynamic range of spICP-MS is limited to two orders of magnitude and as a consequence sample dilution is often required. The precision of the method was found to be <5% and <10% for the determination of particle size and concentration, respectively while the accuracy for particle size (Au NP only) was <10%. The robustness against potential sample matrix components was investigated. The applicability to routine samples was demonstrated by four examples (food, waste water, culture media and biological tissues). The presented combination of spICP-MS measurements with a powerful data evaluation tool enables the use of this technique as a fast, cost efficient and easy to use screening tool for metal and metal oxide NPs that can be widely implemented in the statutory monitoring of food and consumer products for the presence of NPs, as well as in the analytical evaluation of toxicological studies.