Optimisation d’un générateur de microgouttelettes couplé à un appareil de spectrométrie de masse à plasma d’argon à couplage inductif (ICP-MS) pour l’analyse de nanoparticules
Whether synthesized in the laboratory for applications in nanotechnology or naturally formed by erosion, volcanic eruptions, forest fires, etc., the fate of metal nanoparticles in the environment is currently poorly understood. Indeed, their fate can include their dissolution, agglomeration, bioaccumulation, biotoxicity, bioavailability and mobility in natural systems. In order to better understand fate, one of the important parameters to consider is the concentration as well as the size distribution of the nanoparticles. Only a few robust analytical techniques exist that will allow the characterization of metallic nanoparticles at the low concentrations at which they are found in the environment. Single particle inductively coupled plasma mass spectrometry (sp-ICP-MS) is gaining popularity for its speed, low detection limits and potential for isotopic analysis. Presently, liquid samples are generally injected, typically through a pneumatic nebulizer into a spray chamber that results in sample losses on the order of 94-98% since only a small amount of the sample will travel to the detector, while the rest goes to waste. The transport efficiency defines the proportion of sample that actually is measured by the detector and is an essential parameter for determining the concentration of nanoparticles in a sample. The difficulty of precisely calculating the transport efficiency is a known problem in the scientific literature. The variability of the transport efficiency during analysis can lead to very important inaccuracies in the determination of nanoparticle concentrations. The objective of this work was to overcome this problem by coupling a microdroplet generator (MDG) to an inductively coupled plasma mass spectrometer (ICP-MS) in order to significantly increase transport efficiency. To achieve this, it was necessary to optimize all of the parameters involved with the coupling of the microdroplet generator and the ICP-MS, including physical instrumentation, gas flow rates, droplet sizes, etc. Once optimized, nanoparticle standards of different sizes were analyzed to confirm that the introduction method was functional. The final step was to use the microdroplet generator as a method of introduction to analyze nanoparticles in an environmental matrix.
Microdroplet generator Inductively coupled plasma mass spectrometry Size distribution Nanoparticles