Comparison of Spheryx Total Holographic Characterization® with Other Technologies

Total Holographic Characterization^® offers unprecedented precision and accuracy in particle characterization. What sets this unique technology apart is its ability to measure both size AND composition simultaneously. In contrast, traditional dynamic light scattering provides a distribution of particle size alone, without distinguishing similarly sized particles of different composition from each other. In addition, Spheryx’s xSight offers direct measurement of thousands of individual particles, without user inputs, models or assumptions.

Shown below is THC data compared to DLS data. Both techniques provide the information that there are 700 nm particles present in the sample. The extra dimension of information, index of refraction (n), enables THC to distinguish three different 700 nm species in the sample (polystyrene, PMMA and Silica) even though they are the same size.

THC is capable of detecting accurate concentrations down to 500 nm. Traditional direct imaging techniques, such as MFI, lose sensitivity below 5-8 µm and can undercount the number of particles present. Below is a plot of concentration of NIST standard ETFE particles as a function of size as measured by THC and MFI. ETFE has been developed by NIST as a standard for protein aggregates and consists of irregularly shaped particles in a size distribution similar to that of proteins. As you can see from the plot, THC and MFI agree for the larger particle concentrations, but MFI undercounts particles for the smaller sizes.

The plot below demonstrates that THC is in good agreement with SEM in determining the diameter of 500 nm NIST standard polystyrene particles. In this experiment DLS is not as accurate. THC delivers the accuracy of SEM without the need to dry the sample, but rather makes measurements in the native environment.