Does your sample show a peak in the particle size distribution when measured by optical methods such as Dynamic Light Scattering (DLS) or Nanoparticle Tracking Analysis (NTA)? Do you feel confident that the peak you see is an accurate representation of the true particle size distribution in your sample? Light scattering techniques are heavily biased towards detection of large particles because the intensity of scattered light increases as the 6th power of particle diameter. While these techniques are still frequently used, awareness is growing that they commonly report misleading results—even showing a false peak in the particle size distribution when in fact none exists. In order to properly characterize submicron particle distributions, researchers need innovative orthogonal techniques. Spectradyne’s nCS1TM is a non-optical, electrical technique that is truly orthogonal to light-based methods and accurately measures the size and concentration of particles in a sample. The technology is a practical, easy-to-use implementation of resistive pulse sensing (RPS, commonly known as the Coulter principle), a method that has been trusted for decades for characterizing large particles. Spectradyne’s implementation of RPS counts and sizes particles as small as 50 nm, independently of particle material or sample polydispersity. The nCS1 delivers accuracy in particle size and concentration at the nanoscale that is unprecedented in a bench-top instrument. In this presentation, a brief overview of Spectradyne’s Microfluidic RPS (MRPSTM) is given, and case studies are presented that compare the nCS1 to DLS, NTA, and electron microscopy. These case studies expose the misleading results reported by light scattering technologies in such diverse samples as protein formulations, extracellular vesicles, and nanomedicines. The results emphasize what many scientists increasingly appreciate: As materials become more complex and nanoparticles are more widely deployed, new particle metrology is required to keep up with the demands of materials characterization.

Is that peak real? Separating truth from fiction in particle analysis

256th National Meeting (2018)

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