Methods of Particle Size Determination
There are a number of methods used to monitor particle size distribution. The most popular of which include sieve analysis, direct imaging and laser diffraction. Historically, particle size distributions were calculated based on results from sieve analysis. Sieve analysis presents particle size information in the form of an S – curve of cumulative mass retained on each sieve versus the sieve mesh size. The most commonly used metrics when describing particle size distributions are D-Values (D10, D50 & D90) which are the intercepts for 10%, 50% and 90% of the cumulative mass.
By calculating the relative mass for each particle and summing to get the total mass it is possible to obtain D-values when the particles are arranged in ascending order. The Eyecon™ measures two real diameters for each particle analysed and uses the average of these two dimensions to calculate the 3rd unknown diameter. This allows the Eyecon to construct a cumulative mass distribution in order to obtain required D-values.
For a guide to particle sizing techniques and definitions used within the pharmaceutical industry, download the PDF by filling in the form.