The Coulter Principle for Outlier Detection in Highly Concentrated Solutions

This application note will benefit chemical and material manufacturers concerned about micron and submicron par ticle contamination. Outliers are a common problem in many industrial applications. Outliers can be defined as particles that are significantly larger or smaller than the main particle size distribution, but which occur in a much lower frequency than the main par ticle size. As a simple example, consider a hypothetical sample that contains 1,000,000 particles with a diameter of exactly 10 microns and only one particle with a diameter of 40 microns mixed together. In this sample, the 40-micron particle would be considered an outlier to the main distribution. Detection of outliers presents a special problem in particle characterization, since most instruments are designed to repor t on the average size of a population, and often miss outliers with lower frequency of occurrence. For particle characterization by light scattering, the data can also be highly skewed due to a few large outliers. Larger outliers may dominate the signal because light scattering scales with (radius of particle) to the sixth power. This application note demonstrates the ability of the Coulter Principle to detect outliers in suspensions of highly concentrated small particles. The Coulter Principle for Outlier Detection in Highly Concentrated Solutions Particle Characterization Application Note