Quantitative Evaluation of Nanoparticle Dissolution Kinetics using Single Particle ICP-MS: A Case Study with Silver Nanoparticles

Introduction

Accurate data on engineered nanoparticle (ENP) environmental behavior and the interplay between ENP size, dissolution rate, agglomeration, and interaction with the sample matrix is critical to appropriately characterize the risks these novel materials may pose to environmental health. The advancement of the single particle ICP-MS (SP-ICP-MS) technique is a great benefit for the study of ENPs in natural systems at environmentally relevant (ng/L) concentrations. Previous studies may have obscured environmentally-relevant transformations because of artificially high ENP concentrations used in the experiments1. Therefore, the SP-ICP-MS method is at the forefront to garner the type of information most relevant for environmental risk assessments, namely the precise tracking of changes in ENP size, associated dissolved metal concentration, and determining polydispersity of an ENP sample, all at dilute concentrations in complex solutions. Because dissolution rate is surface-area controlled, the time to complete dissolution is highly dependent on the initial and (potentially stable) intermediate particle sizes. By measuring the change in particle size, as well as the evolution of Ag+(aq) in solution, using SP-ICP-MS, potential pitfalls related to loss of Ag+ to experimental materials and to other environmental surfaces, such as suspended sediments or biota in the case of complex matrices, may be avoided.