Traditional particle sizing techniques like Laser Diffraction (LD) and Dynamic Light Scattering (DLS) often lack the sensitivity required to measure highly diluted samples and low particle concentrations — especially when the component of interest is only a small fraction of the particles in the sample, masked by other, more concentrated populations.
SPES / SPES² (Single Particle Extinction and Scattering) are single-particle techniques that precisely estimate the numerical particle concentration, even of secondary and highly diluted populations. Our patented methods can distinguish and exclude the signals from unwanted populations or the surrounding medium, delivering accurate absolute and relative concentrations for the population of interest.
The figure shows the estimated final concentration of 16 analytical replicates of 0.7 µm polystyrene samples, as a reproducibility study. Concentration values have been corrected by the dilution factor, 20 000 in this case.
The solid red line indicates the expected concentration for the calibrated sample, the dashed red lines are the standard errors given by the manufacturer.
An additional way to asses the accuracy in concentration measurement is to perform different dilutions of known and calibrated polystyrene standards.
In the figure on the right, the measured concentration (vertical axis) is plotted against the expected one (horizontal axis) for different polystyrene samples and diameters, diluted at different concentrations.
The linearity demonstrates the high accuracy of the Classizer™ ONE.
