| Abstract: | Suspension concentrates are dispersions of sparingly soluble active ingredients in water or in organic solvents and generally contain particles with diameters in the range 0.4–12 μm. Four particle size analysis techniques were tested for their suitability for these formulations. Experimental details which are of particular significance for these formulations and methods of presenting the results are discussed for the different techniques. It was found that: the electron microscope was suitable but time-consuming when used without counting devices; the optical microscope was reliable only for the coarse samples, i.e. samples with a median of the volume distribution greater than 2 μm; the Coulter counter model TA was quick and reliable; the centrifugal disc photosedimentometer was also quick and reliable but its suitability decreased with increasing particle size. |
