The identification and accurate size determination of nanoparticles is extremely important given their increasing use in everyday products. However, available techniques such as transmission electron microscopy (TEM) or dynamic light scattering suffer from problems such as artifacts that are introduced during sample preparation.

Qian Liu, Guibin Jiang, and their team, Research Center for Eco-Environmental Sciences (Chinese Academy of Sciences), Beijing, China, have developed an alternative approach. They coupled the separation ability of capillary electrophoresis with the analytical power of inductively coupled mass spectrometry and applied it to the separation and characterization of nanoparticles.

In this technique, the different species (that is, different sized nanoparticles and ions) are first separated by means of their different electrophoretic mobilities, which follow a size-dependent migration mechanism. The migration time is thus proportional to the diameter of the nanoparticles, and size distribution profiles were obtained that were consistent with TEM results. The researchers applied their technique to mixtures of silver and gold nanoparticles and ions, as well as to cleaning products, antibiotic lotions, and water samples. This method provides an accurate technique for the identification and size determination of mixtures of nanoparticles and can be applied in areas such as nanotoxicology.

• Identification and Accurate Size Characterization of Nanoparticles in Complex Media,
  Lihong Liu, Bin He, Qian Liu, Zhaojun Yun, Xueting Yan, Yanmin Long, Guibin Jiang,
  Angew. Chem. Int. Ed. 2014.
  DOI: 10.1002/anie.201408927