Content Handbook F

Outline of method

The method is based on the rate of settling of particles in suspension in a liquid of known viscosity. A suspension of the sample is successively decanted into a series of beakers. A cumulative curve of particle size is constructed.

42.1 Formulations without carriers

The sample is made into a suspension of unit particles. This is then successively decanted into a series of beakers.

42.2 Formulations containing carriers

A suspension is successively decanted as in MT 42.1. Separate determinations of the total weight (active ingredient plus carrier) and the active ingredient for each successive deposit are made.
These determinations give the particle size of the active ingredient and also that of the carrier.