Quantification of Metallic Nanoparticles with ICP-TOFMS

Simultaneous Mass Quantification of Nanoparticles of Different Composition in a Mixture by Microdroplet Generator-ICPTOFMS

Olga Borovinskaya1, Sabrina Gschwind2, Bodo Hattendorf2, Martin Tanner1, Detlef Guenther2
1TOFWERK AG, Thun Switzerland, 2ETH, Zurich, Switzerland

This paper describes the analysis and quantification of metallic nanoparticles (NPs), pure and core-shell NPs mixed in the same solution. This work shows unique advantages of TOFWERK’s icpTOF: Time Resolution and Quantification.

Time Resolution. Time resolved multi-element signals allow distinction between different types of NPs; pure or core-shell. Comparing the TOF data with recently published analysis of the same core-shell particles that uses state-of-the-art quadrupole technology (see figure below) makes the advantage of TOF technology evident. Each particle gave 4 or more data points per element using the TOF. This is very important for a reliable analysis. In contrast, a fast switching quadrupole generates 1 or sometimes 2 data points per particle and element and no indication is given whether any of these points is an indication of the ‘real’ signal maximum. Even though the instrument sensitivities might be the same according to specs, the quad instrument sensitivity needs to be ‘divided’ among the number of analytes. The quad is already pushed to its limit with two analytes for these NPs, but the TOF performance is independent of whether there is a single element to be monitored or e.g. 30.

Quantification. Particle mass could reliably be quantified without the use of reference NPs,  by instead using only liquid multi-element standard solutions. This has great potential since solid standard materials are usually rare, expensive and difficult to handle. A TOF is the only MS capable of simultaneously analyzing multi-element solutions in the form of single micrometer size droplets. This is an indispensable prerequisite for this quantification approach.